Module 3: Neurologic and Neuromuscular Drugs Flashcards
Types of Skeletal muscle relaxants
- Centrally acting: through CNS
- Direct-acting: on muscle
Types of Neuromuscular blocking drugs
- Non-depolarizing
- Depolarizing
Types of Anti-parkingsonian drugs
- Anti-cholinergic
- Dopaminergic
- COMT inhibitors
Anti-migraine drugs
- 5-HT1-receptor agonists (triptans)
- Ergotamine preparations
Skeletal Muscle Relaxants work to?
Name and describe the 2 Classes:
-Centrally acting?
-Direct-acting?
Relieve musculoskeletal pain, spasm, spasticity
- Act as CNS depressants (diazepam, baclofen, cyclobenzaprine)
- produce muscle weakness (dantrolene)
Centrally Acting
-Mechanism?
-Adverse Effects
- unknown; don’t directly relax skeletal muscle or depress neuronal conduction; are CNS depressants (sedatives, anti-anxiolytics ((antianxiety))
- physical, psychological dependence; withdrawl symptoms
Direct-acting
Drantrolene is the?
Mechanism:
- most commonly used
- interferes with calcium ions involved in skeletal muscle contraction➡muscle relaxation/ weakness; little effect on cardiac, smooth muscle
Neuromuscular Blocking Drugs do what?
Name and describe the two classes:
- Non-depolarizing:
- Depolarizing:
- relax skeletal muscles by disrupting transmission of nerve impulses at motor end plate
- derived from curare alkaloids [atracurium, mivacurium, tubocurarine]
- [succinylcholine]
A Motor End Plate is?
a terminal nerve ending that innervates muscle (instead of another nerve). Nerve impulse releases acetylcholine (ACH) into synaptic cleft to bind receptors on adjacent MUSCLE.
Non-depolarizing blocking
-Derived from?
-Compete with acetylcholine ➡ muscle contracted prevented➡
Antidote:
- curare alkaloids (South American Indians used on arrow tips; paralyzes diaphragm (can’t breath, die)
- prolonged muscle relaxation…but…doesn’t cross blood-brain barrier….so remain conscious, can feel pain, just paralyzed
- anti-cholinesterase drugs [neostigmine, pyridostigmine]
Adverse side effects of Non-depolarizing blocking
-non-depolarizing blockers adverse effects apnea hypotension skin reactions bronchospasm excessive bronchial/salivary secretions
Depolarizing Blocking
-act like acetylcholine, but not 4
- Succinylcholine:
- Adverse Effects:
- but not inactivated by cholinesterase
- Only therapeutic drug in this class; metabolized slower than acetylcholine➡ longer muscle paralysis
- prolonged apnea, hypotension; genetic prediposition increases risk.
Anti-Parkinsonian Drugs:
Parkinson’s disease:
Therapy:
-Anti-cholinergic inhibit?
-Dopaminergics: enhance?
- dopamine deficiency, acetylcholine excess ➡ movement disorders (muscle rigidity, akinesia, temors at rest, posture/balance disturbances)
- inhibit cholinergic effects (movement disorders) [benztropine, diphenhydramine]
- enhance dopamine effects 9sustain motor activity) [levodopa, carbidopaomocriptine, amantadine]
Parkinson’s drugs
- Anti-cholinergic(parasympatholytic) drugs inhibit?
- High acetylcholine excites?
- Adverse Effects
- inhibit acetylcholine action at parasympathetic receptors
- CNS causing parkinsonian termor
- confusion, restlessness, agitation and excitement, drowsiness and insomnia, tachycardia and palpitations, constipation, nausea, vomiting, urine retention, increased intraocular pressure, blurred vision, pupil dilation, photophobia
Parkinson’s drugs: dopaminergic drugs
- Dopaminergic drugs:
- Levodopa:
- Carbidopa:
- act in brain to improve motor function
- inactive until crosses blood-brain-barrier and converted to dopamine
- enhances levodopa’s effectiveness by blocking peripheral conversion, increasing amount into brain.
Dopaminergic adverse evects [levodopa]
- nausea, vomiting
- orthostatic hypotension
- anorexia
- neuroleptic malignant syndrome
- arrhythmias
- irritability
- confuseion
COMT Inhibitors
COMT =
-Used as?
Adverse effects:
Liver function test required?
=Catechol-O-methyltransferase
- used as adjuncts to levodopa-carbidopa therapy in Parkinson patients who experience “wearing-off” symptoms at end of dosing interval
- Life-threatening acute liver failure; rapid withdrawl may lead to parkinsonian crisis
- Liver function test required every 2 weeks for 1st year, tapering thereafter.
Anti-convulsant drugs:
Major drug names:
- phenytoin:
- phenobarbital:
- carbamazepine
- clonazepam, diazepam:
- valproate:
- Gabapentin:
- Topiramate:
Inhibit neuromuscular transmission; prescribed for epilepsy, seizures; numerous adverse effects
- phenytoin is a hydantoin, stabilizes nerves from over-excitement. Used to control seizures, called anticonvulsants, used after surgery to the brain or nervous system. Decreases abnormal electrical activity in the brain
- phenobarbital is a barbiturate, elevates seizure threshold by decreasing post-synaptic excitation. treats insomnia and sedating antianxiety drug.
- carbamazepine is an iminostilbene, inhibits neuromuscular transmission. treats seizures. is an anticonvulsant anti-epileptic drug
- clonazepam is a benzodiazepine, safest, fewest side effects, has sedative pro[erties
- valproate is a carboxylic acid derivative, thought to increase GABA (an inhibiory neurotransmitter). treats epilepsy and bipolar disorder and to prevent migraine headaches.
- Gabapentin is an analogue of GABA; mechanism unknown. treat partial seizures, neuropathic pain, hot flashes, and restless legs syndrome.
- topiramate thought to block voltage-dependent sodium channels, enhancing activity of GABA receptors and antagonizing glutamate receptors. control seizures, prevent migraine headache once occurs, off label to treat bulimia
Anti-Migraine Drugs
2 types of treatment:
- Abortive:
- Prevention:
2 classes:
-5-HT1 -receptor agonists (triptans):
-Ergotamine preparations:
- Abortive are for after migraine starts to relieve pain
- Prevention are before migraines start
- constrict ranial vessels, inhibit neuropeptide release, reduce neurogenic inflammatory process
- less selective for 5-HT receptors; block neurogenic inflammation; effectivness increased with coffee [ergotamine]
Triptans
- Contraindications:
- Safety?
Many?
- not for use in patients with ischemic heart disease (angina, myocardial infarction), cerebro-vascular syndromes (stroke), coronary artery disease (hypertension, smoking, obesity, hypercholesterolemia, diabetes)
- safety of treating 3+ migraines in 30-day period not established
- Many drug interactions
