1. Muscle relaxants By
Dr. Mirza Shahed Baig

3. 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.

6. 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

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

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

13. Dantrolene

20. Chlormezanone
Chlorzoxazone
Carisoprodol

22. 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.