Products
Methocarbamol is approved in tablet form (Metoflex). However, it is an older active ingredient, as it was first approved in the United States, for example, in the 1950s.
Structure and properties
Methocarbamol (C11H15NO5, Mr = 241.2 g/mol) is a carbamate derivative. It exists as a white powder and is sparingly soluble in water. Methocarbamol is structurally closely related to the cough suppressant guaifenesin, which is also a muscle relaxant at high doses.
Effects
Methocarbamol (ATC M03BA03) has muscle relaxant and depressant properties on striated skeletal muscle. The effects are due to inhibition of polysynaptic reflex conduction in the spinal cord and subcortical centers. Methocarbamol has a short half-life of 2 hours.
Indications
For the symptomatic treatment of painful muscle spasms, particularly of the low back (lumbago) in adults.
Dosage
According to the SmPC. The tablets are taken three times a day. They may also be administered four times daily at the beginning of therapy. The duration of use should not exceed 30 days.
Contraindications
- Hypersensitivity
- Pregnancy and lactation
- Comatose or precomatose states
- Diseases of the central nervous system
- Myasthenia gravis
- Epilepsy
Full precautions can be found in the drug label.
Interactions
Methocarbamol may potentiate the effects of centrally depressant drugs as well as alcohol and anticholinergics.
Adverse effects
Adverse effects are rare according to the SmPC. Rarely occurring adverse effects include:
- Agitation, anxiety, confusion
- Headache, dizziness, metallic taste
- Conjunctivitis
- Low blood pressure
- Nasal congestion
- Angioedema, rash, itching, hives.
- Fever
Methocarbamol may impair driving and ability to operate machinery. It may discolor urine to brown, black, blue, or green when stored.
