SKELETAL MUSCLE RELAXANT CLASSIFICATION BASED ON SITE OF ACTION A. CENTRALLY ACTING Skeletal Muscle Relaxants OR Centrally Acting SPASMOLYTICS – act at the CNS at diff. receptors to reduce abnormally elevated muscle tone caused by neurologic or muscle end plate disease a. For Chronic spasms Diazepam , a benzodiazepine that is an agonist of GABA A receptor Baclofen , a GABA B agonist Tizanidine , a clonidine congener, an α 2 -agonist These 3 drugs act are administered Orally and act at spinal cord level to reduce the tonic output of Primary spinal Motoneurons b. for Acute spasms Cyclobenzarapine (prototype) Methocarbamol Metaxolone Ophenadrine These drugs are also given Orally & act majorly at the brainstem level to relieve acute muscle spasm caused by local tissue trauma or muscle strains . They are ineffective in trting muscle spasm due to cerebral palsy or spinal cord injury . c. Others Botilinum toxin Local injection of botulinum toxin is a useful treatment for generalized spastic disorders (eg, cerebral palsy). Antiseizure drugs – Gabapentin and Pregabalin Effective spasmolytics in patients with multiple sclerosis. Progabide - a GABA A and GABA B Agonist Glycine Idrocilamide and riluzole Newer drugs for the treatment of amyotrophic lateral sclerosis (ALS), possibly through inhibition of glutamatergic transmission in the central nervous system. B. PERIPHERAL ACTING Skeletal muscle relaxant Neuromuscular Blockers – resembles Ach (except Decamethonium) & act at the neuromuscular jxn nicotinic receptors to relax muscle a. Depolarizing NMBs Succinyl choline (Suxamethonium) Decamethonium b. Non- depolarizing Long-acting (> 35 min) a.
- Spring '17
- DR SHITTU
- Histamine, nicotinic receptors, skeletal muscle relaxant, end plate