| Item |
Information |
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Drug Groups
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approved |
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Description
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A centrally acting muscle relaxant whose mode of action has not been established. It is used as an adjunct in the symptomatic treatment of musculoskeletal conditions associated with painful muscle spasm. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1206) |
| Indication |
For use as an adjunct to rest, physical therapy, and other measures for the relief of discomforts associated with acute, painful musculoskeletal conditions. |
| Pharmacology |
Methocarbamol is a central muscle relaxant for skeletal muscles, used to treat spasms. It is structurally related to guaifenesin. Methocarbamol's exact mechanism of causing skeletal muscle relaxation is unknown. It is thought to work centrally, perhaps by general depressant effects. It has no direct relaxant effects on striated muscle, nerve fibers, or the motor endplate. It will not directly relax contracted skeletal muscles. The drug has a secondary sedative effect. |
| Toxicity |
Symptoms of overdose include blurred vision, coma, drowsiness, low blood pressure, nausea, and seizures. |
| Affected Organisms |
| • |
Humans and other mammals |
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| Biotransformation |
Hepatic. |
| Absorption |
Rapid. Onset of action is about 30 minutes after oral administration. |
| Half Life |
1.14-1.24 hours |
| Elimination |
Small amounts of unchanged methocarbamol also are excreted in the urine. |
| Clearance |
* 0.2 – 0.8 L/h/kg [healthy] |
| References |
| • |
Sica DA, Comstock TJ, Davis J, Manning L, Powell R, Melikian A, Wright G: Pharmacokinetics and protein binding of methocarbamol in renal insufficiency and normals. Eur J Clin Pharmacol. 1990;39(2):193-4.
[Pubmed]
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