Pharmacological assessment of 3‐tert‐butylsydnone

The pharmacological effects of the mesoionic derivative, 3‐tert‐butylsydnone, were investigated. Administration to rats caused clonic convulsions. The CD₅₀ of 3‐tert‐butylsydnone was 0.471 ± 0.033 mmole/kg. Trimethadione, but not phenytoin sodium or proadifen hydrochloride, protected the rat from the effects of 3‐tert‐butylsydnone. After administration of this compound, pentobarbital sodium sleeping time was reduced in the rat, but blood pressure and ECG were unchanged in the dog. Pretreatment of the mouse with 3‐tert‐butylsydnone did not influence the LD₅₀ of epinephrine hydrochloride. The action of methacholine chloride in the rat was not blocked, and the pupil of the rabbit eye was unaffected. Tests for analgesic and oxytocic activity were negative. Chronic administration of a small dose to the rat for 70 days had no effect on blood glucose, blood urea nitrogen, hemoglobin, or microhematocrit values.