Effects of oxazolidines derived from (-) ephedrine in the rat.

1. Five oxazolidines were synthesized by reaction of (-) ephedrine with aliphatic aldehydes. The aldehydes used were formaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde and trimethylacetaldehye. 2. These five oxazolidines were tested in rats for ephedrine-like pharmacological activity using the hyperthermia and anorexia models. 3. All five oxazolidines caused significant elevation of body temperature in the hyperthermia model. The oxazolidine synthesized from (-) ephedrine and butyraldehyde caused greatest hyperthermia. 4. Four oxazolidines caused significant anorectic responses. The oxazolidine synthesized from (-) ephedrine and isobutyraldehyde caused greatest anorexia. 5. A possible tolerance to the anorectic effects of some of the compounds was observed.