Phenprobamate (Gamaquil, Isotonil) is a centrally acting skeletal muscle relaxant, with additional sedative and anticonvulsant effects. Overdose is similar to barbiturate. Its mechanism of action is probably similar to meprobamate. Phenprobamate was previously used in humans as an anxiolytic, and is still sometimes used in general anaesthesia and for treating muscle cramps and spasticity. Phenprobamate is still used in some european countries, but it has generally been replaced by newer drugs. Phenprobamate is metabolised by oxidative degradation of the amide group and ortho-hydroxylation of the benzene ring, and is eliminated in urine by the kidneys.

Dose: 400 – 800 mg, up to 3 times a day.

• The Comparative Toxicogenomics Database: Phenprobamate

• BIAM: Phenprobamate (French).

• Chembank: Phenprobamate
• Nephrology Dialysis Transplantation Volume 17, Number 5, Pp. 941. Letters: Haemoperfusion may be useful in phenprobamate and polypharmacy intoxication of paediatric patients.