Muscle relaxants By Dr. Mirza Shahed Baig

What are Muscle Relaxants (MR) A muscle relaxant is a drug that affects  skeletal muscle  (Skeletal muscles are anchored to bone, either directly or by a tendon)function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia.

Skeletal muscle relaxants Are drugs used to induce muscle relaxation Classification Peripherally acting (Neuromuscular blockers). Centrally acting skeletal muscle relaxants e.g. Baclofen - Diazepam Direct acting skeletal muscle relaxants e.g. Dantrolene

Peripheral Acting Neuromuscular Junction Blockers (NMJ Blockers) 1) NON DEPOLARIZING NEUROMUSCULAR BLOCKERS ISOQUINOLINE DERIVATIVES D- TUBOCURARINE GALLAMINE ATRACURIUM CIS ATRACURIUM ALCURIUM DOXACURIUM MIVACURIUM

STEROID DERIVATIVES PANCURONIUM VECURONIUM RAPACURONIUM PIPECURONIUM ROCURONIUM 2) DEPOLARIZING NEUROMUSCULAR BLOCKERS SUXAMETHONIUM (SUCCINYLCHOLINE) DECAMETHONIUM

Dantrolene

Chlormezanone Chlorzoxazone Carisoprodol

Benzodiazepines (BDZ) as Muscle Relaxants Benzodiazepines may also be used to relieve skeletal muscle spasticity and its accompanying pain in a variety of neurologic disorders including stroke and spinal cord injury. Spasticity likely results from a relative difference between excitatory and inhibitory signals in the spinal cord. Consequently, there is excessive muscle tone and hyperactive stretch reflexes. Benzodiazepines exert their muscle relaxant properties by central potentiation of GABA release. In particular, they bind to specific sites on the GABA type A receptor complex, enhancing the interaction between the receptor and chloride ion channel. The metabolism of benzodiazepines occurs in the liver, and some have active metabolites (e.g., diazepam). Thus, caution must be exercised to prevent toxicity, including excessive sedation and cognitive impairment.