Pharm 8.2 -Muscuranic blockers Flashcards
Anticholinergic drugs are also called
antimuscarinic or parasympatholytics
atropine is abtained from
atropa belladona
antimuscaranic drugs are classified as
natruarl alkaloids, synthetic, and antiparkinsonism
natural alkaloids drugs
atropine and scopolamine
synthetic drugs
homatropine, ipratropium, oxybutynin, cyclopentolate, tropicamide, dicyclomine, pirenzepine, glycopyrrolate, tolterondine
antiparkisonism drugs
trihexyphenydyl, procylidine, benztropine
atropine blocks
muscarinic receptors competitively
atropine structure
teriary amine, so enters BBB
atropine works both
centrally and peripherally
atropine actions on the CVS
tachycardia (due to blockade of Ach M2 receptors on SA node, also facilitates AV conduction, NO marked effect on BP, dialate blood vessels in facial blush area (atropine flush) that is not related to the antagonistic action (due to hyperthermia with resulting vasodialation)
atropine actions on the eye
mydriasis, cycloplegia
atropine induces mydriasis by
blocking the parasympathetic tone to the iris circular muscle – unopposed sympathetic timulation of the radial muscle results in dialation of the pupil
atropine induced cycloplegia is
paralysis of accomodation due to blockage of M3 receptors on ciliary muscle - cannot focus near giving rise to blurring vision
accomodation is caused by changes in the
lens - cliary muscle constirction allows for relaxation, lens widening allowing you to see close - cholinergic receptors
atropine duration
7-10 days
atropine usual concentration %
0.5-1%
scopolamine duration
3-7 days
scopolamine usual concentration
0.25%
homatropine duration of effect
1-3 days
homatropine usual concentration
2-5%
cyclopentolate duration of effect
1 day
cyclopentolate usual concentration
0.5 -2%
tropicamide duration of effect
0.25 days
tropicamide usual concentration
0.5 to 1%
Atropine actions on Smooth muscles
relaxation of SM leading to – GIT peristalsis inhibition/constipation, Bronchus dialation, urinary bladder retention due to relaxation of bladder and constriction of sphincter and trigone
atropine actions on glands by M3 rec
decreases secretions of salivary glands, thermoregulatory sweat gland, tracheobronchial tree, acid in the stomach and lacrimal gland
atropine can casue body temperature to
increase
atropine on CNS
minimal CNS stimulant action in usual doses but high doses cause –restlessness, excitement, hallucinations, disorientation, inhibits vestibular disturbances (esp in motion sickness)
tremor of parkinson’s disease is reduced by centrally acting anti-muscarinic drugs like
trihexyphenyldyl, benztropine
what drugs prevent or reverse vestibular disturbances of motion sickness
atropine, scopolamine
with increasing dose atropine (in order)
decreases secretions, mydriasis and cycloplegia, hyperthermia, tachycardia, sedation, urinary retention and constipation, behavioural excitation and hallucinations
atropine is absorbed from the
GIT
Atropine can freely penetrate the
cornea
half life of atropine is
4 hours
which drug has better passage to the brain, atropine or scopolamine?
scoplamine
uses of atropine substitutes
preanesthetic medication, peptic ulceration, antispasmodic, bronchial asthma and COPD, mydriatic and cycloplegic agent, bradycardia, antidote to organophosphorus poisoning, parkinsonism and drug-induced extrapyramidal dysfunction, overactive bladder, motion sickness
atropine substitutes for preanesthetic medication
hyoscine, glycopyrrolate
atropine substitutes for peptic ulceration
pirenzepine
atropine substitutes for antispasmodic
hyoscine, glycopyrrolate, dicyclomine
atropine substitues for bronchial asthma and COPD
Ipratropium, Tiotropium
atropine substitutes for mydriatic and cycloplegic effects
tropicamide, homatropine, cyclopentolate
atropine substitutes for parkinsonism
trihexyphenydyl, benztropine
atropine substitutes for overactive bladder
oxybutynin, tolterodine, trospium, solifernacin, darifenacin
atropine substitutes for motion sickness
scopolamine
adverse effects of atropine
blurred vision (mydriasis and cycloplegia), dry mouth, fever, constipation, urinary retention, tachycardia, agitations, hallucinations, delirium
contraindications of atropine
glaucoma (narrow angle), urinary retentions (esp BPH patients)