Muscle Relaxants
Definition
Medications that act as central nervous system depressants
They have sedative and musculoskeletal relaxant properties
Fit for short-term use for acute, painful musculoskeletal conditions.
Muscle relaxants are not a separate class of drugs but include drugs from different classes of drugs
Generally used with a pain relieving medication and physiotherapy
Indications
Spasticity from upper motor neuron syndromes and muscular pain or spasms from peripheral musculoskeletal conditions.
Acute back pain, tension head ache
Drugs
Baclofen
Chlorazoxazone
Methocarbamol - acute muscle pain, adjunct therapy in tetanus
Tizanidine - for muscle spasticity - multiple sclerosis, spinal cord injury, cerebral palsy - avoid using with ciprofloxacin
Carisoprodol
Orphnadrine
Diazepam - a benzodiazepine - for muscle spasms, anxiety, alcohol withdrawal, seizure disorders : epilepsy
Clonidine, gabapentin
Botulinum toxin
Mechanism of Action
Baclofen - blocks pre and post synaptic GABAb receptors
Tizanidine - Centrally acting agonist of α2 receptors
Dandrolene - directly decreases the release of calcium from skeletal muscle sarcoplasmic reticulum
Diazepam - a benzodiazepine - centrally blocks GABAa receptors
Side Effects
Drug abuse
Habit formation
Alteration of sleep cycles
worsens mental depression
Not in pregnancy
Interaction with antihistamines
Interaction with alcohol
Drowsiness
Blurred vision
Light headedness, confusion
Urnary retention
Abrupt stopping not advisable - tapered slowly
