Muscle Relaxants Flashcards
(16 cards)
compare centrally acting and direct acting agents
central - CST
direct - peripheral reflex arc or excitation-contraction coupling in skeletal muscles
discuss baclofen mechanism of action
GABA mimetic at GABA B receptors - inc K kaya hyperpolarized
inhibits release of excitatory NT
inhibits release of substance P
uses of baclofen
relieve painful spasticity in MS
spasticity from SCI
trigeminal neuralgia and tardive dyskinesia
chronic pain management
not useful in CP
pharmakokinetics of baclofen
dose: 15-100 mg/d
absorption: almost completely absorbed in GIT
metabolism: liver
half-life: 3-6 hours
excretion: renal
adverse effects of baclofen
muscle weakness and fatigue
ataxia
nausea
HA
mild OH
drowsy, dizzy, sedation
teratogenicity
special precautions for baclofen
dec threshold for seizures
sudden withdrawal causes hallucinations, anxiety and tachycardia
discuss mech of action of diazepam
inc availability of glycine - skeletal mscule relax and anti-anxiety
faci action of GABA - anticonvulsant and sedative effects
uses of diazepam
spasticity in cord lesions
muscle spasm 2° MSK injuries
CP
pharmacokinetics of diazepam
absorption (oral): GIT peak in 1-1.5 hrs
metabolism: hepatic microsomal using oxidative pathway
half-life: 21-37 hrs
metabolites:
- desmethyldiazepam: slighly more potent
- half life: 48-96 hrs - oxazepam: rapidly removed as conjugate
adverse reactions of diazepam
drowsy, dizzy and sedation - esp geria
respi depression
hypotension
bradycardia
discuss other central relaxants
blocks inter-neuronal activity in SC
epirisone
tizanidine
methocabamol
orpheradine
chlozoxazone
adjucnt for tx in acute, painful in MSK conditions
side effects of other central releaxants
DDS but not as severe
give a direct acting agent drug
dantrolene
discuss dantrolene
blocks Ca release in SR
for severe spasticity regardless of etiology
oral and IV
adverse effects of dantrolene
generalized weakness
hepatotoxicity
DDS
pharmacokinetics for dantrolene
dose: 25 mg to 400mg /d
absorption: 1/3 of oral dose
metabolism: liver
half-life: 8 hrs
excretion: renal
