Muscle Relaxants

Authors: Flaherty, Alice W.; Rost, Natalia S.

Title: Massachusetts General Hospital Handbook of Neurology, The, 2nd Edition

Copyright 2007 Lippincott Williams & Wilkins

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Muscle Relaxants

A. See also

Benzodiazepines, p. 165.

B. Baclofen

A GABA-B agonist. For spasticity, back pain, trigeminal neuralgia.

• Dosing: Start 5-10 mg PO bid, to 10-30 tid.

• Side effects: Sedation, weakness, nausea, depression. If stopped suddenly after several weeks of heavy use, can trigger seizures.

C. Dantrolene

A direct muscle relaxant.

• Dosing: see p. 170 for dosing in neuroleptic malignant syndrome. For spasticity, start 25 mg PO qd, up to 400 mg qd divided bid/qid.

P.174




• Side effects: Hepatotoxicity, CHF, sedation.

D. Tizanidine (Zanaflex)

₂-adrenergic agonist, used for spasticity.

• Dosing: Varies widely across pts., from 2-39 mg PO qd; must titrate over 2-4 wk because it takes about a week to reach max. effect.

• Side effects: Sedation, weakness (less than baclofen), dry mouth.

E. Cyclobenzaprine (Flexeril)

Central muscle relaxant.

• Dosing: 5-10 mg tid; do not use for more than 3 weeks.

• Side effects: Sedation, dizziness, dry mouth.

F. Quinine

Not an FDA-approved indication, but helps some pts.

• Dosing: Try 300 mg PO qhs.

• Side effects: Cinchonism with overdose. Hemolysis with G6PD deficiency.