Carisoprodol - Central Skeletal Muscle Relaxants

Carisoprodol

Synonyms

Carisoprodate; Isobamate; Isopropyl meprobamate.

Uses

·              Carisoprodol is related structurally and pharmacologically to meprobamate and is a CNS depressant with muscle relaxant properties.

·              It is usually used as an adjunct to analgesics in the relief of acute musculoskeletal pain.

Clinical (Toxic) Features

·      Blood levels of over 30 mcg/ml are associated with toxicity.

·      Overdose results in drowsiness, lethargy, vertigo, diplopia, nystagmus, headache, ataxia, tachycardia, convulsions, and coma.

·      Horizontal and vertical nystagmus, mydriasis and blurred vision may occur.

·      Sinus tachycardia with a prolonged QT interval has been reported.

·      Death can occur. Survival may be associated with amnesia relating to events during the course of toxicity.

·      Chronic therapeutic use may cause skin rash, drowsiness, nausea, vertigo, ataxia, tremor and headache.

·      Sudden cessation of chronic therapy can cause a with-drawal reaction: anxiety, tremors, muscle twitching, insomnia, auditory and visual hallucinations, bizarre behaviour.

Treatment

·      Stomach wash if the patient is seen within 3 to 4 hours, activated charcoal, and cathartics.

·      Supportive measures usually suffice to reverse the toxic effects.

·      Flumazenil has been used with beneficial effects (0.2 mg IV, repeated as required).