Anticholinergics Flashcards
Muscarinic blockers belladonna alkaloid drugs
- Atropine
- Scopolamine
Muscarinic blockers tertiary amines drugs
- Tolterodine and Oxybutynin (Antispasmodics)
- Tropicamide (Mydriatics)
- Benztropine and Diphenhydramine (Antiparkinsonian)
Muscarinic blockers quarternary amines drugs
- Glycopyrrolate
- Ipratropium
- Tiotropium
Ganglionic Blocking Agent drugs
- Nicotine (Depolarizing)
ANTICHOLINERGIC DRUGS MOA
- Block action of ACh at cholinergic receptors throughout body
Anticholinergic drugs subdivisions
- Muscarinic blockers
- Ganglionic blockers
- Neuromuscular blockers
Muscarinic blockers MOA
(e. g., atropine, propantheline)
- Inhibit cholinergic transmission at postganglionic parasympathetic receptor sites, e.g., on smooth muscle, cardiac muscle, and exocrine glands: M (muscarinic) receptors
Ganglionic blockers MOA
e. g., mecamylamine, trimethaphan
- Block cholinergic transmission at autonomic ganglia in both parasympathetic and sympathetic nerve fibers: N (nicotinic) I sites
Neuromuscular blockers MOA
e. g., pancuronium
- Reduce action of ACh at synapses between nerves and skeletal muscles (neuromuscular junction): N (nicotinic) II receptors.
Major pharmacologic actions of anticholinergic drugs
- GI
↓ motility (reduced smooth muscle tone) —> constipation
↓ secretions - CV
Tachycardia (small doses of atropine can produce bradycardia) - Urinary Tract
Contraction of sphincter muscle; relaxation of detrusor muscle —> urinary retention
-Eye
Relaxes ciliary muscle: cycloplegia (paralysis of
accomadation) - Exocrine Glands
↓ sweating, salivation and mucous formation (e.g., nasal) - Smooth Muscle
Relaxation of non-vascular smooth muscle (e.g., biliary, bronchiolar, intestinal, uterine) - CNS
Decreased sensitivity to motion
Drowsiness, disorientation, possible hallucinations
Decreased skeletal muscle activity (e.g., decreased tremor)
Belladonna alkaloid MOA
- Atropine and scopolamine are the principal naturally occurring anticholinergic drugs
- Rapidly absorbed after p.o. administration
- Relatively selective blocking action at M receptor sites Readily enter the CNS
- Blockade (via competitive antagonism) of acetylcholine at postsynaptic muscarinic receptor sites
- Large doses block cholinergic transmission at autonomic ganglia and the neuromuscular junction
Belladonna alkaloids major therapeutic uses
- Production of mydriasis and cycloplegia to facilitate eye exam
- Preop to reduce excess salivation and preventbradycardia
- Reduction of GI motility
- Reduce muscarinic side effects
- Relief of nasopharyngeal and bronchial secretions
- Relief of bronchoconstriction
- Prevention and relief of motion sickness
- Treatment of enuresis
- Treatment of sinus bradycardia
- Sedation and amnesia
- Antidote to overdosage with cholinergic agents
- Relief of symptoms of parkinsonism
Belladonna alkaloids ADR’s
GI - Dry mouth, constipation, paralytic ileus Cardiovascular - Tachycardia Ocular - Blurred vision, increased intraocular tension GU - Urinary retention
Belladonna alkaloids contraindications
- Narrow-angle glaucoma
- Myasthenia gravis
- Asthma (atropine)
Belladonna alkaloids effects increased by
antihistamines, tricyclic anti- depressants, antipsychotics
Tertiary Amines MOA
- Good lipid-solubility
- Well absorbed after p.o.
- Wide distribution into peripheral and central tissues
Oxybutinin ADR’s
- Tertiary amine
- Bladder instability (e.g., urinary leakage)
Tolterodine ADR’s
- Tertiary amine
- Bladder instability (e.g., urinary leakage)
Antispasmodics major therapeutic uses
- Oxybutinin and Tolterodine
- Range from slight to no anticholinergic activity
- minimal reduction of gastric secretion
- Direct relaxant effect on smooth muscle (nonspecific)
Mydriatics major therapeutic uses
- Tropicamide
- To produce mydriasis and cycloplegia for eye exam; also employed in treatment of uveitis
Mydriatics ADR’s
- Danger of systemic absorption; possible toxic side effects include:
➢ disorientation
➢ retrograde amnesia
➢ hallucinations
➢ cardiac arrhythmias: - atrial fibrillation; supraventricular tachycardia
➢ death (in children)
Antiparkinsonian Agents
Employed in clinical conditions related to imbalance between acetylcholine (Ach) and dopamine (DA)
- Benztropine
- Diphenhydramine
Benztropine MOA
- Blockade of DA sites allows greater action of ACh
- More selective than belladonna alkaloids.
Diphenhydramine MOA
- Blockade of DA sites allows greater action of ACh
- More selective than belladonna alkaloids
- Antihistamine with central antichol. activity
- Appears to have less peripheral side effects than other agents
- Sedative effect beneficial in pts with insomnia
