Treatments involving eslicarbazepine acetate or eslicarbazepine

FIELD OF THE INVENTION

The invention relates to new therapeutic techniques involving eslicarbazepine acetate or eslicarbazepine.

BACKGROUND OF THE INVENTION

An epileptic seizure is defined as a clinical event associated with a transient, hypersynchronous neuronal discharge. The seizure represents only the symptom of a potential underlying brain pathology and not the actual disease. Epilepsy, in contradistinction to seizures, is a chronic disorder characterised by recurrent seizures. Epilepsy affects approximately 1% of the population.

Partial-onset seizures are a variety of epileptic seizure which affect only a part of the brain at onset. The seizure often remains localized, but may spread more widely throughout the brain. Partial seizures are generally divided into simple partial seizures, complex partial seizures and partial seizures secondarily generalised.

In contrast, absence seizures, also known as petit mal seizures, are a form of generalized seizure, which affects the whole of the brain, producing abnormal electrical activity throughout both hemispheres and, typically, loss of consciousness. Absence seizures are brief, generalized epileptic seizures with two characteristic features: (1) impairment of consciousness (absence) and (2) particular spike-and-slow wave discharges as measured by electroencephalography (EEG). The clinical manifestations of absence seizure may vary significantly among patients, and their etiology is not well defined or understood. Absence seizures generally occur more frequently in children than adults. Other varieties of generalized seizures include tonic-clonic seizures (grand mal), e.g. primary generalized tonic clonic seizures, myoclonic seizures, atonic seizures, clonic seizures and tonic seizures.

Eslicarbazepine acetate ((S)-10-acetoxy-10,11-dihydro-5H-dibenz[b,f]azepine-5-carboxamide) is a potent voltage-gated sodium channel blocker described, e.g., in WO-A-97/02250, WO-A-2006/121363, WO-A-2007/094694, WO-A-2008/088233, WO-A-2009/054743, WO-A-2011/014084, and WO-A-2011/031176, the contents of which applications are incorporated herein by reference. Eslicarbazepine acetate has been approved by the European Medicines Agency (EMA) for adjunctive therapy for partial-onset seizures, with or without secondary generalization, in adults with epilepsy.

Eslicarbazepine acetate is one of several drugs in the carboxamide dibenzazepine family. Other drugs in this family include oxcarbazepine (10,11-dihydro-10-oxo-5H-dibenz[b,f]azepine-5-carboxamide, OXC) and carbamazepine (5H-dibenzo[b,f]azepine-5-carboxamide, CBZ).

Drugs in the carboxamide dibenzazepine family are used to treat partial-onset seizures. However, drugs in this class are known to aggravate general seizures, specifically absence seizures. Such aggravation of absence seizures is mediated via enhanced activity at the gamma amino butyric acid (GABA.sub.A) receptor. Thus, Liu et al (J Pharmacol Exp Ther 319:790-798) explains that the activity of carbamazepine in aggravating absence seizures arises from the activity of the drug in enhancing activity at the GABA.sub.A receptor. Similarly, oxcarbazepine has also been linked with enhanced activity at the GABA.sub.A receptor and aggravation of absence seizures (Zheng T et al, Epilepsia, 50(1): 83-87, 2009).

Given that oxcarbazepine and carbamazepine aggravate absence seizures, it was therefore expected that other members of the carboxamide dibenzazepine family, such as eslicarbazepine acetate should not be used to treat patients who suffer from absence seizures. This is explained, for example, in the standard clinicians' reference book "The Treatment of Epilepsy", 3.sup.rd edition, eds. Shorvon, Perucca & Engel, Chapter 38 (Almeida, L et al) (2009), which explains on page 497 that, based on the fact that eslicarbazepine acetate is structurally related to oxcarbazepine and carbamazepine, eslicarbazepine acetate may be expected to be potentially aggravating on some primary seizure types, particularly myoclonic and absence seizures.

Shorvon et al also explain at page 485 that the efficacy spectrum of eslicarbazepine acetate is restricted to partial epilepsies. Thus, there is no expectation in the art that eslicarbazepine acetate would have any effect in treating primary generalized seizures, such as absence seizures and primary generalized tonic clonic seizures. Many of the animal models which have historically been used to test antiepileptogenic properties of compounds are unable to distinguish between efficacy against primary generalized seizures and secondary generalized seizures. Further, many of the animal models may give results which are not directly applicable to the treatment of primary generalized seizures in human patients.

Primary generalized tonic clonic seizures in particular are not well understood, and their mechanism differs from that of secondary generalized tonic clonic seizures. Thus, whilst off label use of drugs licensed exclusively for treating partial seizures has been reported in some secondary generalized seizures, such use has not been reported in primary generalized seizures.

SUMMARY OF THE INVENTION

Eslicarbazepine acetate is metabolized in vivo in humans to the active metabolite, eslicarbazepine ((S)-10-hydroxy-10,11-dihydro-5H-dibenz[b,f]azepine-5-carboxamide), with R-licarbazepine and OXC as minor metabolites. Details can be found in "The Treatment of Epilepsy", 3.sup.rd edition, eds. Shorvon, Perucca & Engel, Chapter 38 (Almeida, L et al) (2009), the contents of which are incorporated herein by reference.

Oxcarbazepine is also known to be metabolized in vivo in humans to eslicarbazepine and R-licarbazepine in a ratio of approximately 4:1.

It has now surprisingly been found that, contrary to the general understanding in the art, eslicarbazepine acetate and eslicarbazepine do not in fact aggravate absence seizures. Rather, they have antiepileptogenic activity in preventing or reducing the incidence of absence seizures.

Thus, it is a finding of the present invention that unlike oxcarbazepine and carbamazepine, eslicarbazepine is essentially devoid of effects upon GABA.sub.A receptor currents. It is another finding of the present invention that eslicarbazepine, in contrast to R-licarbazepine, oxcarbazepine and carbamazepine, effectively inhibits high and low affinity inward currents in T-type calcium channels. Transcriptional induction of T-type calcium channels is a critical step in epileptogenesis and neuronal vulnerability, so this finding demonstrates that eslicarbazepine and eslicarbazepine acetate will have antiepileptogenic effects and will be effective in preventing or reducing the incidence of absence seizures.

Advantageously, therefore, the findings of the present invention allow treatment of epilepsy, affective disorders, schizoaffective disorders, bipolar disorders, neuropathic pain and neuropathic pain related disorders, attention disorders, anxiety disorders, sensorimotor disorders, vestibular disorders, and fibromyalgia with eslicarbazepine or eslicarbazepine acetate in patients susceptible to absence seizures.

The epilepsy is typically partial onset seizures.

In a first embodiment, the present invention therefore provides a drug selected from eslicarbazepine acetate and eslicarbazepine, for use in treating or preventing a disorder selected from epilepsy such as partial-onset seizures, affective disorders, schizoaffective disorders, bipolar disorders, neuropathic pain and neuropathic pain related disorders, attention disorders, anxiety disorders, sensorimotor disorders, vestibular disorders, and fibromyalgia, in a patient suffering from or susceptible to absence seizures.

In a second embodiment, the present invention provides a pharmaceutical composition for use in treating or preventing a disorder as defined herein, in a patient as defined herein, which pharmaceutical composition comprises a pharmaceutically acceptable carrier and, as active principle, a drug as defined herein.

In a third embodiment, the present invention provides use of a drug as defined herein, or a pharmaceutical composition as defined herein, in the manufacture of a medicament for use in treating or preventing a disorder as defined herein, in a patient as defined herein.

In a fourth embodiment, the present invention provides a method of treating or preventing a disorder as defined herein, in a patient as defined herein, which method comprises administering to said patient a safe and effective amount of a drug as defined herein, or a pharmaceutical composition as defined herein.

In a fifth embodiment, the present invention provides a method of treating or preventing a disorder as defined herein, which method comprises (a) selecting a patient as defined herein, and (b) administering to said patient a safe and effective amount of a drug as defined herein, or a pharmaceutical composition as defined herein.

In a sixth embodiment, the present invention provides a drug selected from eslicarbazepine acetate and eslicarbazepine, for use in treating or preventing, such as delaying the onset or reducing the incidence, severity or duration of absence seizures.

In a seventh embodiment, the present invention provides a pharmaceutical composition for use in preventing or reducing the incidence of absence seizures, which pharmaceutical composition comprises a pharmaceutically acceptable carrier and, as active principle, a drug as defined herein.

In an eighth embodiment, the present invention provides use of a drug as defined herein, or a pharmaceutical composition as defined herein, in the manufacture of a medicament for use in preventing or reducing the incidence of absence seizures.

In a ninth embodiment, the present invention provides a method of preventing or reducing the incidence of absence seizures in a patient, which method comprises administering to said patient a safe and effective amount of a drug as defined herein, or a pharmaceutical composition as defined herein.

DESCRIPTION OF THE FIGURES

FIG. 1 shows representative current traces at .alpha.1.beta.2.gamma.2 GABA receptors for eslicarbazepine, R-licarbazepine, carbamazepine (CBZ), bicucculine and midazolam in Ltk cells using a whole-cell patch-clamp technique.

FIG. 2 shows representative current traces for eslicarbazepine, R-licarbazepine, oxcarbazepine (OXC) and carbamazepine (CBZ) and mibefradil at the high affinity (top) and low affinity (bottom) binding sites for hCa.sub.v3.2 calcium channels stably expressed in HEK cells using a whole-cell patch-clamp technique.

FIG. 3 shows Inhibition dose-response curves for the blockade of hCa.sub.v3.2 currents by eslicarbazepine, R-licarbazepine, CBZ, OXC and mibefradil in HEK cells using a whole-cell patch-clamp technique.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the words "treatment" and "treating" are to be understood as embracing treatment and/or amelioration and/or prevention of or reduction in aggravation/worsening of symptoms of a disease or condition as well as treatment of the cause of the disease or condition, and may include reversing, reducing, or arresting the symptoms, clinical signs, and underlying pathology of a condition in manner to improve or stabilise a subject's condition.

Reference to "prevention" and "preventing" a disease embraces prophylaxis and/or inhibition of the disease. The term "preventing" is art-recognized, and when used in relation to a condition, such as a local recurrence (e.g., pain), a disease such as cancer, a syndrome complex such as epilepsy or pain or any other medical condition, is well understood in the art, and includes administration of a composition which reduces the frequency of, or delays the onset of, symptoms of a medical condition in a subject relative to a subject which does not receive the composition. Thus, prevention of epilepsy includes, for example, delaying the onset or reducing the number (incidence), frequency, severity or duration of seizures, such as absence or partial onset seizures, in a population of patients receiving a prophylactic treatment relative to a control population untreated with eslicarbazepine or eslicarbazepine acetate, e.g., by a statistically and/or clinically significant amount. Prevention of pain, such as fibromyalgia, neuropathic pain or neuropathic pain related disorders includes, for example, reducing the magnitude of, or alternatively delaying, pain sensations experienced by subjects in a treated population versus a control population untreated with eslicarbazepine or eslicarbazepine acetate. Prevention of bipolar disorders includes, for example, reducing the number of manic, hypomanic, cyclothymic, psychotic or depressive episodes in a treated population versus a control population untreated with eslicarbazepine or eslicarbazepine acetate.

Typically, the patient is a human patient.

Affective disorders include depression, pre-menstrual dysphoric disorder, post-partum depression, post-menopausal depression, anorexia nervosa, bulimia nervosa, and neurodegeneration-related depressive symptoms.

Schizoaffective disorders include schizodepressive syndromes, schizophrenia, extreme psychotic states, schizomanic syndromes, dysphoric and aggressive behavior, episodic dyscontrol or intermittent explosive disorder, and borderline personality disorder.

Bipolar disorders include bipolar disorder and unstable bipolar disorder with rapid fluctuations (rapid cyclers), manic-depressive disorders, acute mania, mood episodes, and manic and hypomanic episodes.

Attention disorders include attention deficit hyperactivity disorders (attention deficit disorders) and other attention disorders such as autism.

Anxiety disorders include conditions social anxiety disorders, post-traumatic stress disorder, panic, obsessive-compulsive disorder, alcoholism, drug withdrawal syndromes, and cravings.

Neuropathic pain and neuropathic pain-related disorders are described in. WO-A-2007094694 and include neuropathic pain and associated hyperalgesia, including trigeminal, herpetic, post-herpetic and tabetic neuralgia, diabetic neuropathic pain, migraines, tension-type headaches, causalgia, and deafferentation syndromes such as brachial plexus avulsion.

Sensorimotor disorders include restless legs syndrome, spasticity, hemifacial spasm, nocturnal paroxysmal dystonia, brain ischemia associated motor and sensitive deficits, Parkinson's disease and parkinsonian disorders, antipsychotic-induced motor deficits, tardive dyskinesia, episodic nocturnal wandering, and myotonia.

Vestibular disorders include tinnitus or other inner ear/cochlear excitability related diseases, such as neuronal loss, hearing loss, sudden deafness, vertigo, and Meniere's disease.

Fibromyalgia is a well-known disorder, and is described in, for example, WO-A-2011/014084.

Typically, the disorder is epilepsy, particularly partial-onset seizures. Partial-onset seizures are a well-known disorder typically associated with epilepsy. Partial seizures may also be referred to as focal or localized seizures. Partial seizures include simple partial seizures and complex partial seizures. Partial-onset seizures may present with or without secondary generalization.

Typically, the disorder is partial onset seizure, neuropathic pain, a neuropathic pain-related disorder or fibromyalgia.

Typically, the drug is eslicarbazepine acetate.

Preferably, the drug is eslicarbazepine acetate, and the disorder is partial-onset seizures.

Absence seizures are a well-known type of seizure, more commonly occurring in females. Typically, therefore, the patient is female. Absence seizures are generally divided into typical and atypical absence seizures.

Typical absence seizures usually occur in patients having idiopathic generalised epilepsies and an EEG of patients having typical absence seizures shows fast >2.5 Hz generalised spike-wave discharges, for example greater than about 3 Hz. Cognitive impairment is not often seen with typical absence seizures.

Atypical absence seizures typically occur only in children suffering from severe symptomatic or cryptogenic epilepsies, who usually also present with learning difficulties. Such patients typically also suffer from frequent seizures of other types such as atonic, tonic and myoclonic. Onset and termination of an atypical absence seizure is not so abrupt as in typical absence seizures, and changes in tone are more pronounced. EEG of patients having atypical absence seizures usually shows slow <2.5 Hz spike and slow wave patterns, for example from about 1 to about 2 Hz. The discharge experienced in an atypical seizure is heterogeneous, often asymmetrical and may include irregular spike and slow wave complexes, fast and other paroxysmal activity. Background interictal EEG is usually abnormal.

Children and adolescents are more susceptible to absence seizures than adults. Many children who suffer from absence seizures grow out of them as they get older. Typically, therefore, the patient susceptible to absence seizures is a child or adolescent. Typically, the patient is under about 20 years old, preferably under about 18 years old, more preferably under about 17 years old, even more preferably under about 16 years old, even more preferably under about 15 years old, even more preferably under about 14 years old, for example, from about 2 to about 13 years old, from about 9 to about 13 years old, from about 10 to about 15 years old, from about 4 to about 8 years old, or from about 5 to about 7 years old. Thus, typically, the patient has not yet reached puberty.

Patients susceptible to absence seizures will typically have been diagnosed as suffering from absence seizures. Patients susceptible to absence seizure will more typically have previously suffered from at least one seizure such as an absence seizure, myclonic seizure or tonic-clonic seizure, preferably an absence seizure.

Patients susceptible to absence seizures may have a family history of epilepsy and/or may already have experienced other seizures types prior to experiencing absence seizures, for example generalized tonic-clonic seizures (which may often be experienced on awakening) or myoclonic seizures. Thus, typically, the patient has a family history of epilepsy. Therefore patients susceptible to absence seizures, and in particular atypical absence seizures, may show interictal abnormalities on electro-encephalogram (EEG), and may have previously experienced multiple types of seizure, and may show cognitive abnormalities or mental retardation.

Particular genetic abnormalities may be present in patients susceptible to absence seizures, for example, the .gamma.-aminobutyric acid (GABA).sub.A receptor .gamma.-2 subunit mutation R43Q. Thus, typically, the patient has the R43Q mutation in the .gamma.-aminobutyric acid (GABA).sub.A receptor .gamma.-2 subunit. Patients susceptible to absence seizures may or may not be photosensitive.

Idiopathic generalized epilepsies which present with absence seizures include childhood (or infantile) absence epilepsy, juvenile absence epilepsy, myoclonic absence epilepsy, juvenile myoclonic epilepsy and Lennox-Gastaut syndrome. Other proposed generalized epilepsies associated with absence seizures include perioral myoclonus with absences, Jeavons syndrome (eyelid myoclonus with absences) and idiopathic generalised epilepsy with phantom absences. Thus, typically, the patient is suffering from or susceptible to childhood absence epilepsy, juvenile absence epilepsy, myoclonic absence epilepsy, juvenile myoclonic epilepsy, Lennox-Gastaut syndrome, perioral myoclonus with absences, Jeavons syndrome or idiopathic generalised epilepsy with phantom absences. Preferably, the patient is suffering from or susceptible to childhood absence epilepsy, juvenile absence epilepsy, myoclonic absence epilepsy, juvenile myoclonic epilepsy or Lennox-Gastaut syndrome.

Primary generalized tonic clonic seizures are a well-known type of seizure, which like absence seizures affect the whole brain. Primary generalized tonic clonic seizures involve two phases, the tonic phase and the clonic phase. In the tonic phase, patients typically display a rigid contracture of muscles, including respiratory muscles. The tonic phase is usually brief. In the clonic phase, patients typically display rhythmic shaking. The clonic phase is usually longer than the tonic phase. Together, a generalized tonic clonic seizure is also called a grand mat seizure.

Primary generalized tonic clonic seizures are idiopathic, i.e. they occur without any apparent cause and are typically not preceded by a partial seizure. Primary generalized tonic clonic seizures may present on awakening.

The drugs for use in the present invention may be administered as monotherapy treatment for the indication or with other drug(s) as adjunct therapy for the indication, as described in more detail below. In the case of adjunct therapy, the drugs for use in the present invention may be administered simultaneously or sequentially with the other drug(s), for example in fixed dose combination or in separate doses.

The drugs for use in the present invention may be administered by any suitable route to provide a therapeutic effect against partial-onset seizures, neuropathic pain or fibromyalgia. Thus, they can be administered orally, for example as tablets, capsules, caplets, troches, lozenges, aqueous or oily suspensions, dispersible powders or granules. The drugs may also be administered parenterally, whether subcutaneously, intravenously, intramuscularly, intrasternally, transdermally or by infusion techniques. The drugs may also be administered as suppositories.

Typically, the drugs are for oral administration.

In one embodiment, the drugs are administered as a tablet.

In another embodiment, the drugs are administered as a suspension. This embodiment is explained further in WO-A-2011/031176, the content of which is incorporated herein by reference.

In a further embodiment, the drugs are administered as a granule or sprinkle formulation. This embodiment is explained further in WO-A-2012/091593, the content of which is incorporated herein by reference.

The drugs for use in the present invention may be administered once a day, or more than once a day, for example two, three or four times a day. Typically, the drugs are for once daily administration. This is explained further in WO-A-2006/121363, the content of which is incorporated herein by reference.

Dosages will vary depending on, e.g., the individual, the mode and frequency of administration, and the nature and severity of the condition to be treated. A clinician having ordinary skill in the art can readily determine and prescribe the effective amount required.

Typical doses for a patient will range from 1 mg per kilogram to 50 mg per kilogram of body weight per day, preferably 5 mg per kilogram to 45 mg per kilogram of body weight per day, more preferably 10 mg per kilogram to 40 mg per kilogram of body weight per day, even more preferably 5, 10, 15, 20, 25 or 30 mg per kilogram of body weight per day. A typical daily oral dose of the drugs is from 100 mg to 1.200 mg per day, preferably from 200 mg to 800 mg per day, more preferably from 400 to 600 mg per day. EMA approved dosages of eslicarbazepine acetate for adjunctive therapy for partial-onset seizures, with or without secondary generalisation, in adults with epilepsy are 400 mg, 800 mg, or 1200 mg daily.

Eslicarbazepine acetate and eslicarbazepine are particularly effective adjuncts for use with other drugs. The findings of the present invention mean that eslicarbazepine acetate and eslicarbazepine are particularly advantageous for use in treating or preventing a disorder selected from epilepsy such as partial-onset seizures, affective disorders, schizoaffective disorders, bipolar disorders, neuropathic pain and neuropathic pain related disorders, attention disorders, anxiety disorders, sensorimotor disorders, vestibular disorders, and fibromyalgia in a patient susceptible to absence seizures who is being treated with a drug which may cause or aggravate their absence seizures. Thus, for example, in the case of epilepsy (such as partial onset seizure), a patient may be receiving a second antiepileptic drug which may cause or aggravate absence seizures, for example carbamazepine, oxcarbazepine, vigabatrin, tiagabine, phenytoin, phenobarbital, gabapentin, or pregabalin. By substituting eslicarbazepine acetate and eslicarbazepine for part of one of these drugs, an antiepileptic effect may still be achieved without aggravating absence seizures.

Eslicarbazepine acetate and eslicarbazepine may also be used in combination with another drug (adjunct therapy) which is effective against epilepsy such as partial-onset seizures, affective disorders, schizoaffective disorders, bipolar disorders, neuropathic pain and neuropathic pain related disorders, attention disorders, anxiety disorders, sensorimotor disorders, vestibular disorders, and fibromyalgia. Such drugs will be well known to the skilled person. In the case of epilepsy (such as partial onset seizure), clorazepate, clonazepam, ethosuximide, felbamate, fosphenytoin, lacosamide, lamotrigine, levetiracetam, primidone, topiramate, valproate semisodium, valproic acid, and zonisamide are all approved by the FDA, for treating epilepsy, but are not counterindicated against absence seizures. However, eslicarbazepine acetate and eslicarbazepine may also be administered as monotherapy for the indication.

In a second embodiment, the present invention provides a pharmaceutical composition for use in treating or preventing a disorder as defined herein, in a patient as defined herein, which pharmaceutical composition comprises a pharmaceutically acceptable carrier and as active principle, a drug as defined herein.

Said pharmaceutical composition typically contains at least 50 wt % of a drug as defined herein. More typically, it contains at least 80 wt % of a drug as defined herein. Preferred pharmaceutical compositions are sterile and pyrogen free.

Eslicarbazepine acetate and eslicarbazepine are typically formulated for administration with a pharmaceutically acceptable carrier or diluent. For example, solid oral forms may contain, together with the active compound, diluents, e.g. lactose, dextrose, saccharose, cellulose, corn starch or potato starch; lubricants, e.g. silica, talc, stearic acid, magnesium or calcium stearate, and/or polyethylene glycols; binding agents; e.g. starches, arabic gums, gelatin, methylcellulose, povidone, carboxymethylcellulose or polyvinyl pyrrolidone; disaggregating agents, e.g. starch, alginic acid, alginates, croscarmellose soldium or sodium starch glycolate; effervescing mixtures; dyestuffs; sweeteners; wetting agents, such as lecithin, polysorbates, laurylsulphates; and, in general, non toxic and pharmacologically inactive substances used in pharmaceutical formulations. Such pharmaceutical preparations may be manufactured in any known manner, for example, by means of mixing, granulating, tableting, sugar coating, or film coating processes.

Liquid dispersions for oral administration may be syrups, emulsions and suspensions. The syrups may contain as carriers, for example, saccharose or saccharose with glycerine and/or mannitol and/or sorbitol.

Suspensions and emulsions may contain as carrier, for example a natural gum, xanthan gum, agar, sodium alginate, pectin, methylcellulose, carboxymethylcellulose, or polyvinyl alcohol. The suspension or solutions for intramuscular injections may contain, together with the active compound, a pharmaceutically acceptable carrier, e.g. sterile water, olive oil, ethyl oleate, glycols, e.g. propylene glycol, a wetting agent, for example polyoxyethylene stearate, an antimicrobial agent, such as methylparaben or propylparaben, and if desired, a suitable amount of lidocaine hydrochloride.

Solutions for injection or infusion may contain as a carrier, for example, sterile water or preferably they may be in the form of sterile, aqueous, isotonic saline solutions.

Typically, the pharmaceutical composition is in the form of a tablet, granule (sprinkle) formulation (i.e. for sprinkling on food) or suspension. Suitable suspensions are described in WO-A-2011031176.

In a third embodiment, the present invention provides use of a drug as defined herein, or a pharmaceutical composition as defined herein, in the manufacture of a medicament for use in treating or preventing a disorder as defined herein, in a patient as defined herein.

Typically, in this embodiment, the medicament is for coadministration with a second drug which may cause or aggravate absence seizures, for example carbamazepine, oxcarbazepine, vigabatrin, tiagabine, phenytoin, phenobarbital, gabapentin, or pregabalin.

Typically, in this embodiment, the medicament is for coadministration with one or more additional medications (adjunct therapy) for treatment of epilepsy such as partial-onset seizures, affective disorders, schizoaffective disorders, bipolar disorders, neuropathic pain and neuropathic pain related disorders, attention disorders, anxiety disorders, sensorimotor disorders, vestibular disorders, and fibromyalgia. In the case of epilepsy (such as partial onset seizure), the additional medicament is typically chosen from clorazepate, clonazepam, ethosuximide, felbamate, fosphenytoin, lacosamide, lamotrigine, levetiracetam, primidone, topiramate, valproate semisodium, valproic acid, and zonisamide. However, the medicament may also be administered as monotherapy for the indication.

In a fourth embodiment, the present invention provides a method of treating or preventing a disorder as defined herein, in a patient as defined herein, which method comprises administering to said patient a safe and effective amount of a drug as defined herein, or a pharmaceutical composition as defined herein.

Typically, in this embodiment, the drug is coadministered with a second drug which may cause or aggravate absence seizures, for example carbamazepine, oxcarbazepine, vigabatrin, tiagabine, phenytoin, phenobarbital, gabapentin, or pregabalin.

Typically, in this embodiment, the drug is coadministered with one or more additional medications (adjunct therapy) for treatment of epilepsy such as partial-onset seizures, affective disorders, schizoaffective disorders, bipolar disorders, neuropathic pain and neuropathic pain related disorders, attention disorders, anxiety disorders, sensorimotor disorders, vestibular disorders, and fibromyalgia. In the case of epilepsy (such as partial onset seizure), the additional medicament is typically chosen from clorazepate, clonazepam, ethosuximide, felbamate, fosphenytoin, lacosamide, lamotrigine, levetiracetam, primidone, topiramate, valproate semisodium, valproic acid, and zonisamide. However, the drug may also be administered as monotherapy for the indication.

In a fifth embodiment, the present invention provides a method of treating or preventing a disorder as defined herein, which method comprises (a) selecting a patient as defined herein, and (b) administering to said patient a safe and effective amount of a drug as defined herein, or a pharmaceutical composition as defined herein.

Typically, in this embodiment, the drug is coadministered with a second drug which may cause or aggravate absence seizures, for example carbamazepine, oxcarbazepine, vigabatrin, tiagabine, phenytoin, phenobarbital, gabapentin, or pregabalin.

Typically, in this embodiment, the drug is coadministered with one or more additional medications (adjunct therapy) for treatment of epilepsy such as partial-onset seizures, affective disorders, schizoaffective disorders, bipolar disorders, neuropathic pain and neuropathic pain related disorders, attention disorders, anxiety disorders, sensorimotor disorders, vestibular disorders, and fibromyalgia. In the case of epilepsy, the additional medicament is typically chosen from clorazepate, clonazepam, ethosuximide, felbamate, fosphenytoin, lacosamide, lamotrigine, levetiracetam, primidone, topiramate, valproate semisodium, valproic acid, and zonisamide. However, the drug may also be administered as monotherapy for the indication.

As discussed above, eslicarbazepine acetate and eslicarbazepine have advantageous antiepileptogenic properties which make them effective in preventing or reducing the incidence of absence seizures.

In a sixth embodiment, therefore, the present invention provides a drug selected from eslicarbazepine acetate and eslicarbazepine, for use in preventing or reducing the incidence of absence seizures. Typically the drug provides control of absence seizures, even when complicated by other seizure types, for example by reducing the frequency and/or severity of absence seizures.

Typically, the drug is eslicarbazepine acetate.

Typically, the drug is for use in treating a patient who is suffering from or susceptible to absence seizures, as defined herein.

Typical dosages of the drug are as defined above.

Typically, in this embodiment, the drug is for coadministration with one or more additional medications (adjunct therapy) for treatment of absence seizures. Such medications are well-known to the skilled person, and include sodium valproate, valproic acid, ethosuximide and lamotrigine. However, the drug may also be administered as monotherapy for the indication.

In a seventh embodiment, the present invention provides a pharmaceutical composition for use in preventing or reducing the incidence of absence seizures, which pharmaceutical composition comprises a pharmaceutically acceptable carrier and, as active principle, a drug as defined herein.

Typical pharmaceutical compositions and pharmaceutically acceptable carriers are as defined herein.

In an eighth embodiment, the present invention provides use of a drug as defined herein, or a pharmaceutical composition as defined herein, in the manufacture of a medicament for use in preventing or reducing the incidence of absence seizures.

Typically, the medicament is for use in preventing or reducing the incidence of absence seizures in a patient who is suffering from or susceptible to absence seizures, as defined herein.

Typically in this embodiment, the medicament is for coadministration with one or more additional medications (adjunct therapy) for treatment of absence seizures, as defined herein. However, the medicament may also be administered as monotherapy for the indication.

In a ninth embodiment, the present invention provides a method of preventing or reducing the incidence of absence seizures in a patient, which method comprises administering to said patient a safe and effective amount of a drug as defined herein, or a pharmaceutical composition as defined herein.

Typically, the patient is a patient suffering from or susceptible to absence seizures, as defined herein.

Typically in this embodiment, the drug is coadministered with one or more additional medications (adjunct therapy) for treatment of absence seizures, as defined herein. However, the drug may also be administered as monotherapy for the indication.

The antiepileptogenic properties of eslicarbazepine acetate and eslicarbazepine also make them effective in preventing or reducing the incidence of primary generalized tonic clonic seizures.

In a tenth embodiment the present invention provides a drug selected from eslicarbazepine acetate and eslicarbazepine, for use in preventing or reducing the incidence of primary generalized tonic clonic seizures.

Typically the drug provides control of primary generalized tonic clonic seizures, even when complicated by other seizure types, for example by reducing the frequency and/or severity of primary generalized tonic clonic seizures.

Typically, the drug is eslicarbazepine acetate.

Typically, the drug is for use in treating a patient who is suffering from or susceptible to primary generalized tonic clonic seizures, as defined herein.

Typical dosages of the drug are as defined above.

Typically, in this embodiment, the drug is for coadministration with one or more additional medications (adjunct therapy) for treatment of primary generalized tonic clonic seizures. Such medications are well-known to the skilled person, and include sodium valproate, valproic acid, ethosuximide, lamotrigine, topiramate, zonisamide, levetiracetam and rufinamide. Preferably agents for coadministration are sodium valproate, valproic acid, ethosuximide and lamotrigine. However, the drug may also be administered as monotherapy for the indication.

In an eleventh embodiment, the present invention provides a pharmaceutical composition for use in preventing or reducing the incidence of primary generalized tonic clonic seizures, which pharmaceutical composition comprises a pharmaceutically acceptable carrier and, as active principle, a drug as defined herein.

Typical pharmaceutical compositions and pharmaceutically acceptable carriers are as defined herein.

In a twelfth embodiment, the present invention provides use of a drug as defined herein, or a pharmaceutical composition as defined herein, in the manufacture of a medicament for use in preventing or reducing the incidence of primary generalized tonic clonic seizures.

Typically, the medicament is for use in preventing or reducing the incidence of primary generalized tonic clonic seizures in a patient who is suffering from or susceptible to primary generalized tonic clonic seizures, as defined herein.

Typically in this embodiment, the medicament is for coadministration with one or more additional medications (adjunct therapy) for treatment of primary generalized tonic clonic seizures, as defined herein. However, the medicament may also be administered as monotherapy for the indication.

In a thirteenth embodiment, the present invention provides a method of preventing or reducing the incidence of primary generalized tonic clonic seizures, in a patient, which method comprises administering to said patient a safe and effective amount of a drug as defined herein, or a pharmaceutical composition as defined herein.

Typically, the patient is a patient suffering from or susceptible to primary generalized tonic clonic seizures, as defined herein.

Typically in this embodiment, the drug is coadministered with one or more additional medications (adjunct therapy) for treatment of primary generalized tonic clonic seizures, as defined herein. However, the drug may also be administered as monotherapy for the indication.

The treatments described herein are also effective in treating patients who are suffering from both absence seizures and primary generalized tonic clonic seizures.

In a fourteenth embodiment the present invention provides a drug selected from eslicarbazepine acetate and eslicarbazepine, for use in preventing or reducing the incidence of both absence seizures and primary generalized tonic clonic seizures.

Typically the drug provides control of both absence seizures and primary generalized tonic clonic seizures, even when complicated by other seizure types, for example by reducing the frequency and/or severity of absence seizures and/or primary generalized tonic clonic seizures.

Typically, the drug is eslicarbazepine acetate.

Typically, the drug is for use in treating a patient who is suffering from or susceptible to absence seizures and/or primary generalized tonic clonic seizures, as defined herein.

Typical dosages of the drug are as defined above.

Typically, in this embodiment, the drug is for coadministration with one or more additional medications (adjunct therapy) for treatment of absence seizures and/or primary generalized tonic clonic seizures. Such medications are well-known to the skilled person, and include sodium valproate, valproic acid, ethosuximide, lamotrigine, topiramate, zonisamide, levetiracetam and rufinamide. Preferably agents for coadministration are sodium valproate, valproic acid, ethosuximide and lamotrigine. However, the drug may also be administered as monotherapy for the indication.

In a fifteenth embodiment, the present invention provides a pharmaceutical composition for use in preventing or reducing the incidence of both absence seizures and primary generalized tonic clonic seizures, which pharmaceutical composition comprises a pharmaceutically acceptable carrier and, as active principle, a drug as defined herein.

Typical pharmaceutical compositions and pharmaceutically acceptable carriers are as defined herein.

In a sixteenth embodiment, the present invention provides use of a drug as defined herein, or a pharmaceutical composition as defined herein, in the manufacture of a medicament for use in preventing or reducing the incidence of both absence seizures and primary generalized tonic clonic seizures.

Typically, the medicament is for use in preventing or reducing the incidence of absence seizures and/or primary generalized tonic clonic seizures in a patient who is suffering from or susceptible to absence seizures and/or primary generalized tonic clonic seizures, as defined herein.

Typically in this embodiment, the medicament is for coadministration with one or more additional medications (adjunct therapy) for treatment of absence seizures and/or primary generalized tonic clonic seizures, as defined herein. However, the medicament may also be administered as monotherapy for the indication.

In a seventeenth embodiment, the present invention provides a method of preventing or reducing the incidence of both absence seizures and primary generalized tonic clonic seizures, in a patient, which method comprises administering to said patient a safe and effective amount of a drug as defined herein, or a pharmaceutical composition as defined herein.

Typically, the patient is a patient suffering from or susceptible to absence seizures and/or primary generalized tonic clonic seizures, as defined herein.

Typically in this embodiment, the drug is coadministered with one or more additional medications (adjunct therapy) for treatment of absence seizures and/or primary generalized tonic clonic seizures, as defined herein. However, the drug may also be administered as monotherapy for the indication.

The following non-limiting Examples illustrate the invention.

EXAMPLES

Example 1

Carbamazepine (CBZ) aggravates absence seizures in `generalized absence epilepsy rats from. Strasbourg`. One putative mechanism for the aggravation is through its reported potentiation of GABA.sub.A currents. A study was carried out to determine the effect of eslicarbazepine, R-licarbazepine and carbamazepine on sub-maximal GABA currents in Ltk cells stably expressing .alpha.1.beta.2.gamma.2, .alpha.2.beta.2.gamma.2, .alpha.3.beta.2.gamma.2 or .alpha.5.beta.2.gamma.2 GABA-receptors. The whole-cell patch-clamp technique was used to investigate the effects of the test compounds on GABAA receptors.

Used Ltk cells were stably transfected with recombinant GABA.sub.A cDNAs: .alpha.1.beta.2.gamma.2, .alpha.2.beta.2.gamma.2, .alpha.3.beta.2.gamma.2 or .alpha.5.beta.2.gamma.2 (B'SYS GmbH, Switzerland). Cells were maintained in a humidified atmosphere (95% relative humidity) with 5% CO.sub.2 and were grown in D-MEM/F-12 (1.times., liquid, with GlutaMax 1) supplemented with 9% foetal bovine serum and 0.9% Penicillin/Streptomycin solution (Gibco BRL). For the electrophysiological experiments cells were cultivated, at a density that enabled single cells to be measured, in medium without antibiotics or antimycotics. Cells were tested 24-48 hours following induction of transgene expression with dexamethasone.

Cells were continuously perfused with bath solution (NaCl 137 mM, KCl 4 mM, CaCl.sub.2 1.8 mM, MgCl.sub.2 1 mM, D-Glucose 10 mM HEPES 10 mM, pH 7.4). The whole-cell patch clamp recordings from transfected Ltk cells (voltage-clamped at a holding potential of -80 mV) were made using a EPC-7, HEKA Electronics amplifier. GABA inward-currents were measured upon application of 1 or 2 .mu.M GABA to patch-clamped cells (at an EC5). Eslicarbazepine, R-licarbazepine, carbamazepine, midazolam (positive allosteric modulator of the GABA.sub.A receptor) or bicuculline (negative allosteric modulator of the GABA.sub.A receptor) were applied by perfusion with GABA.

SigmaPlot 8.02 was used to calculate the means.+-.SEM of relative peak'current blockade for each test item. Analysis of Variance (ANOVA) with post test multisample comparison (Dunnett) was conducted with GraphPad Prism 4 Software.

The effect of eslicarbazepine and R-licarbazepine on GABA inward current stimulation measured on Ltk cells stably transfected with .alpha.1.beta.2.gamma.2, .alpha.2.beta.2.gamma.2, .alpha.3.beta.2.gamma.2 or .alpha.5.beta.2.gamma.2 GABA receptors is shown in the following table.

TABLE-US-00001 TABLE 1 Current stimulation (%) .alpha.1.beta.2.gamma.2 .alpha.2.beta.2.gamma.2 .alpha.3.beta.2.gamma.2 .- alpha.5.beta.2.gamma.2 Compound (.mu.M) Mean .+-. SEM n Mean .+-. SEM n Mean .+-. SEM n Mean .+-. SEM n Vehicle 108.11 .+-. 3.40 3 96.95 .+-. 1.27 5 101.25 .+-. 1.92 5 95.40 .+-. 0.53 5 Eslicarbazepine 50 103.3 .+-. 1.96 3 91.58 .+-. 2.69 5 95.61 .+-. 4.75 5 95.18 .+-. 2.18 5 100 95.92 .+-. 0.83 3 97.04 .+-. 2.65 5 97.93 .+-. 4.22 5 93.89 .+-. 0.60 5 250 97.82 .+-. 1.13 3 88.56 .+-. 3.24** 5 96.44 .+-. 2.16 5 93.52 .+-. 1.75 5 500 99.39 .+-. 0.80 3 89.80 .+-. 4.01 5 91.63 .+-. 5.56 5 89.65 .+-. 3.44 5 R-Licarbazepine 50 99.85 .+-. 1.18 3 96.48 .+-. 2.11 5 99.53 .+-. 2.65 5 96.13 .+-. 0.57 5 100 92.53 .+-. 4.53 3 97.03 .+-. 2.27 5 100.38 .+-. 1.56 5 94.09 .+-. 1.27 5 250 91.73 .+-. 4.69 3 93.79 .+-. 3.09 5 102.94 .+-. 3.34 5 97.24 .+-. 1.58 5 500 95.83 .+-. 6.63 3 87.75 .+-. 1.94* 5 97.35 .+-. 2.91 5 92.25 .+-. 1.29 5 Midazolam 3 184.81 .+-. 32.93* na na na Bicucculline 1 na 27.85 .+-. 3.21 5 34.16 .+-. 3.99 5 39.65 .+-. 4.34 5 Vehicle was 0.2% DMSO for .alpha.1.beta.2.gamma.2 and 0.4% for all the other GABA receptors. *Significantly different from vehicle (P < 0.01). **Significantly different from vehicle (P < 0.05)

The effect of carbamazepine and bicucculline on GABA inward current stimulation measured on Ltk cells stably transfected with .alpha.1.beta.2.gamma.2, .alpha.2.beta.2.gamma.2, .alpha.3.beta.2.gamma.2 or .alpha.5.beta.2.gamma.2 GABA receptors is shown in the following table.

TABLE-US-00002 TABLE 2 Current stimulation (%) .alpha.1.beta.2.gamma.2 .alpha.2.beta.2.gamma.2 .alpha.3.beta.2.gamma.2 .- alpha.5.beta.2.gamma.2 Compound (.mu.M) Mean .+-. SEM n Mean .+-. SEM n Mean .+-. SEM n Mean .+-. SEM n Vehicle 96.19 .+-. 3.71 11 97.58 .+-. 3.59 10 100.29 .+-. 5.92 6 95.25 .+-. 4.61 6 Carbamazepine 50 104.30 .+-. 5.02 6 97.94 .+-. 3.34 5 93.32 .+-. 4.07 6 103.82 .+-. 1.50 6 100 117.38 .+-. 4.94 6 111.36 .+-. 2.65 5 112.76 .+-. 5.40 6 103.83 .+-. 4.53 6 250 115.68 .+-. 5.31 6 109.03 .+-. 7.61 5 131.06 .+-. 9.39 6 93.59 .+-. 4.30 6 500 132.42 .+-. 5.31* 6 103.60 .+-. 7.61 5 120.27 .+-. 11.81 6 80.65 .+-. 5.86 6 1000 150.26 .+-. 15.48* 6 104.18 .+-. 2.66 5 166.66 .+-. 21.00* 6 63.01 .+-. 4.50* 6 Bicuccullin 0.1 70.48 .+-. 3.19** 5 62.71 .+-. 2.57* 5 66.06 .+-. 3.05 5 60.16 .+-. 3.45* 5 1 24.28 .+-. 1.70* 5 16.40 .+-. 2.24* 5 25.82 .+-. 5.11* 5 10.26 .+-. 1.77* 5 3 8.23 .+-. 1.01* 5 2.15 .+-. 1.09* 5 10.45 .+-. 1.39* 5 5.87 .+-. 2.47* 5 30 0.35 .+-. 0.49* 5 1.87 .+-. 1.40* 5 3.07 .+-. 1.42* 5 1.68 .+-. 0.73* 5 Vehicle was 0.4% DMSO. *Significantly different from vehicle (P < 0.01). **Significantly different from vehicle (P < 0.05)

Representative current traces at .alpha.1.beta.2.gamma.2 GABA receptors for eslicarbazepine, R-licarbazepine, carbamazepine (CBZ), bicucculine and midazolam are shown as FIG. 1.

Eslicarbazepine and R-licarbazepine, in contrast to carbamazepine, can be seen to be devoid of effects upon sub-maximal GABA currents.

Example 2

T-type channels are critically important in controlling the excitability of the postsynaptic compartment of neurons, both in normal and epileptic neurons (Huguenard J R. (1996) Annu Rev Physiol 58, 329-348). Aberrant bursting is seen in CA1 hippocampal neurons from epileptic animals that is mediated by increased expression of T-type Ca2+ channels (Sanabria E R G, Su H, Yaari Y. (2001) J Physiol 532, 205-216). Transcriptional induction of T-type calcium channels (Ca.sub.v3.2) is a critical step in epileptogenesis and neuronal vulnerability (Su H, Sochivko D, Becker A, Chen J, Jiang Y Yaari Y, Beck H. (2002) J Neurosci, 22, 3645-3655).

A study was carried out to determine the effect of eslicarbazepine. R-licarbazepine, oxcarbazepine (OXC) and carbamazepine (CBZ) on human T-type calcium channels hCa.sub.v3.2 currents recorded from stably transfected HEK 293 cells. The whole-cell patch-clamp technique was used to investigate the effects of eslicarbazepine, R-licarbazepine, oxcarbazepine and carbamazepine on hCa.sub.v3.2 calcium channels stably expressed in HEK cells.

HEK 293 obtained from European Collection of Animal Cell Culture Cells were maintained in a humidified atmosphere (95% relative humidity) with 5% CO.sub.2 and were grown in D-MEMF-12 (1.times. liquid with GlutaMax I, Gibco BRL) supplemented with 9% foetal bovine serum (GibcoBRL), 0.9% Penicillin/Streptomycin solution (Gibco BRL) and 100 .mu.g/ml Geneticin. Cells were stably transfected with hCa.sub.v3.2 cDNA.

Cells were continuously perfused with bath solution (NaCl 137 mM, KCl 4 mM, CaCl.sub.21.8 mM, MgCl.sub.2 10 mM, D-Glucose 10 mM HEPES 10 mM, pH 7.4). Calcium inward currents were measured upon depolarization of the cell membrane to -25 mV for 50 ms from a holding potential of -80 mV. This voltage protocol was run at intervals of 10 s until stabilization of evoked hCa.sub.v3.2 currents. Once control recordings were accomplished, cells were perfused with bath solution containing eslicarbazepine, R-licarbazepine, oxcarbazepine or carbamazepine (0.3 to 1000 .mu.M) or the reference compounds valproic acid (1 mM) or mibefradil (0.01-10 .mu.M). Vehicle was either bath solution or 0.2% DMSO.

SigmaPlot 8.02 was used to calculate the means.+-.SEM of relative peak current blockade for each compound. Analysis of variance (ANOVA) with post test multisample comparison (Dunnett) was conducted with GraphPad Prism 4 Software. IC.sub.50 were calculated with the equation:

.times..times..times..times..times..times..times..times..times..times..ti- mes..times..times..times..times..times..times..times..times..times..times.- .times. ##EQU00001## where 1 refers to the high affinity fit and 2 to the low affinity fit. X is the compound concentration, y1/y2 is the remaining peak current amplitude, IC50(1)/IC50(2) is the concentration of drug at half maximal inhibition and H1/H2 is the Hill coefficient for the fit.

The effect of eslicarbazepine, R-licarbazepine, carbamazepine (CBZ), oxcarbazepine (OXC) and mibefradil on calcium peak currents on HEK 293 cells expressing the hCa.sub.v3.2 channels is shown in the following table.

TABLE-US-00003 TABLE 3 Relative current amplitude (%) Concentration eslicarbazepine R-licarbazepine CBZ (.mu.M) Mean .+-. SEM n Mean .+-. SEM Mean .+-. SEM OXC Mibefradil n 0.01 84.72 .+-. 3.20 5 0.1 57.32 .+-. 3.97* 5 0.3 86.99 .+-. 1.56* 5 98.42 .+-. 1.33 5 99.10 .+-. 0.57 5 1 81.61 .+-. 1.31* 5 92.43 .+-. 1.41 5 98.04 .+-. 0.63 5 19.11 .+-. 2.58* 5 3 76.21 .+-. 1.61* 9 88.21 .+-. 1.03* 9 94.82 .+-. 0.93 5 10 71.22 .+-. 2.40* 9 82.92 .+-. 1.29* 9 92.83 .+-. 2.76 5 9.13 .+-. 2.31* 5 25 87.58 .+-. 2.94 5 30 73.04 .+-. 1.64* 5 78.21 .+-. 2.14* 5 90.14 .+-. 1.98 5 50 61.44 .+-. 4.96* 4 73.86 .+-. 3.78* 4 76.53 .+-. 5.48 5 100 54.68 .+-. 6.35* 4 71.61 .+-. 1.68* 4 69.98 .+-. 4.47 5 250 46.92 .+-. 6.64* 4 64.52 .+-. 3.05* 4 59.47 .+-. 6.06* 5 500 51.83 .+-. 4.77* 8 58.10 .+-. 2.74* 7 45.66 .+-. 7.45* 5 1000 45.48 .+-. 4.94* 4 39.37 .+-. 5.33* 3 Control values obtained with vehicle were 97.35 .+-. 1.28 (n = 8). Remaining current obtained with 10 mM valproic acid was 65.15 .+-. 2.05% (n = 8). *Significantly different from control (P < 0.01).

Representative current traces for eslicarbazepine, R-licarbazepine, oxcarbazepine and carbamazepine and mibefradil at the high affinity (top) and low affinity (bottom) binding sites are shown as FIG. 2.

Inhibition dose-response curves for the blockade of hCa.sub.v3.2 currents by eslicarbazepine, R-licarbazepine, CBZ, OXC and mibefradil is shown as FIG. 3.

IC.sub.50 values were determined as follows from inhibition curves for eslicarbazepine, R-licarbazepine, carbamazepine (CBZ), oxcarbazepine (OXC) and mibefradil.

TABLE-US-00004 TABLE 4 hCa.sub.v3.2 IC.sub.50 (.mu.M) High Low Compounds affinity affinity Eslicarbazepine 0.43 62.61 R-licarbazepine 6.54 883.10 CBZ 27.10 711.20 OXC nc nc Mibefradil 0.14 nc nc--not calculated

It can be seen that eslicarbazepine, R-licarbazepine and carbamazepine dose dependently inhibited hCa.sub.v3.2 calcium peak currents (Table 3 and FIG. 2). The inhibition curves were best fitted with a two site binding model and a constant remaining current amplitude. A block of high affinity occurs with an IC.sub.50 of 0.43 .mu.M, 6.54 or 27.10 .mu.M for eslicarbazepine, R-licarbazepine and carbamazepine, respectively (table of IC.sub.50 values above and FIG. 3). A further block occurs at higher concentrations of the test items, with an IC.sub.50 of 62.61 .mu.M for eslicarbazepine, 883.10 .mu.M for R-licarbazepine and 711.20 .mu.M for carbamazepine (table of IC.sub.50 values above and FIG. 3). Oxcarbazepine, up to 30 .mu.M, was devoid of effect on hCa.sub.v3.2 currents.

(Regarding the reference compounds, 1 mM valproic acid blocked calcium peak currents by 66.15.+-.2.05 (n=8 cells) and mibefradil dose dependently inhibited hCa.sub.v3.2 calcium peak currents with an IC.sub.50 of 143.7 nM.)

The obtained data demonstrates that eslicarbazepine, in contrast to R-licarbazepine, carbamazepine and oxcarbazepine, effectively inhibits high and low affinity hCa.sub.v3.2 inward currents.

Example 3

Following oral administration of oxcarbazepine, eslicarbazepine acetate, eslicarbazepine and R-licarbazepine in rats, all compounds result in oxcarbazepine. Therefore to test the effects of oral administration of eslicarbazepine acetate, mice models are used.

Administration of eslicarbazepine and eslicarbazepine acetate in the following models is tested: (a) Absence seizure induced by .gamma.-butyrolactone Absence seizure arises from aberrant thalamocortical. Oscillatory burst firing of thalamocortical neurons induces spike and wave discharges (SWDs), and the generation of this firing results from Ca.sup.2+ influx into the thalamocortical neurons via low-threshold calcium channels. .gamma.-Hydroxybutyric acid (GHB) as well as various .gamma.-aminobutyric acid GABA receptor agonists are reported to induce absence seizures. GHB has been proposed as a neurotransmitter/neuromodulator that acts via its own receptor. The systemic injection of GHB into mice elicits rhythmic 3 Hz SWD, the EEG hallmark of absence seizures, and represents a well established and widely used pharmacological model of this nonconvulsive epilepsy. Ryu et al (2007) Journal of Neurochemistry, 102:646-656 (b) Succinic semialdehyde dehydrogenase deficiency The succinic semialdehyde dehydrogenase (SSADH) null mouse represents a viable animal model for human SSADH deficiency and is characterised by markedly elevated levels of both GHB and GABA in brain, blood, and urine. GHB is known to induce absence-like seizures and absence seizures have been reported to occur in children with SSADH deficiency. Sequential electrocorticographic (ECoG) and prolonged video ECoG recordings from chronically implanted electrodes were performed on SSADH/, SSADH+/, and SSADH+/+ mice from postnatal day (P) 10 to (P) 21. Spontaneous, recurrent absence-like seizures appeared in the SSADH/ during the second week of life and evolved into generalized convulsive seizures late in the third week of life that were associated with an explosive onset of status epilepticus which was lethal. The seizures in SSADH null mice were consistent with typical absence seizures in rodent with 7 Hz spike-and-wave discharge (SWD) recorded from thalamocortical circuitry. Cortez et al (2004) Pharmacology, Biochemistry & Behaviour 79:547-553. (c) Stargazer Mouse model. The stargazer (stg) mutant mouse harbors a transposon insertion in the second intron of the calcium channel .gamma.2 subunit (cacng2) locus, disrupting transcription of the gene. The stg mouse has proved to be an exceptionally informative mutant, exhibiting several disorders including spontaneous absence seizure, cerebellar ataxia, and head tossing. Ryu et al (2008) Journal of Neurochemistry 104:1260-1270 (d) C3H/He mouse model The inbred mouse strain C3H/He exhibits spontaneous absence seizures characterized by spike and wave discharges (SWD) on the electroencephalogram concomitant with behavioural arrest. Tokuda et a (2009) Genes, Brain & Behaviour 8:283-289

Results show that eslicarbazepine acetate and eslicarbazepine are effective in controlling seizures in these models.

Example 4

Clinical trial study: A randomised double-blind, placebo controlled, trial assesses the efficacy and safety of adjunctive eslicarbazepine acetate in primary generalised tonic clonic seizure (PGTCS) in human patients in accordance with established methods.

Methods: Men and women are selected for trial according to standard inclusion criteria in the field including the following: Subject is male or female and aged 6-65 years. Subject has .gtoreq.3 PGTCS over the two months before screening and during the eight weeks Baseline Period with at least one seizure in each one month period. PGTCS must occur in the context of Idiopathic Generalized Epilepsy (IGE) and may be accompanied by other primary generalized seizures, provided these are also consistent with a diagnosis of IGE. Subject is taking a stable regimen of one or two other Antiepileptic Drugs (AEDs) for at least two weeks prior to Visit 1 (start of the Baseline Period). Subject has a clinical diagnosis of any type of idiopathic generalized epilepsy which has PGTCS (and which may be accompanied by other generalized seizure types), according to the International League Against Epilepsy (ILAE) Classification of Epileptic Seizures (1981) and the ILAE Classification of Epilepsies and Epileptic Syndromes (1989). Diagnosis should have been established by clinical history, electroencephalogram (EEG) and computed tomography/magnetic resonance imaging (CT/MRI) of the brain consistent with idiopathic generalized epilepsy. CT/MRI scan should have been performed within five years of the screening visit or, if not available from this period, should be performed in the Baseline Period. EEG should have been performed within one year of the screening visit or, if not available from this period, should be performed in the Baseline Period. Subject has a body weight .gtoreq.20 kg.

Patients may be excluded from trial in accordance with known exclusion criteria in the field.

Patients selected for trial are randomised to treatment sequences comprising eslicarbazepine acetate at effective dosage and placebo administered by conventional means.

Trial endpoints assessed clinical criteria are as follows: time to withdrawal after randomisation; time to first, second, or other seizure after randomisation (time to first seizure after randomisation allows determination of the proportion of patients at different time points who remain seizure free); time to achieving remission (e.g. at six months, one year, or two years); change in seizure severity; change in seizure frequency; percentage response to treatment (response defined as a 50% or greater reduction in seizure frequency); change in seizure-free interval; change in seizure duration; change in seizure pattern; change in functional capacity; and patient-related quality of life.

CONCLUSION

Treatment with eslicarbazepine acetate in patients suffering from or susceptible to PGTCS leads to improved clinical effects indicating usefulness of eslicarbazepine acetate adjunct or monotherapy in treating PGTCS.