Parasympathomimetic/ Cholinergic Agonist Flashcards
Drugs acting on both nicotinic and M receptor
Ach, carbachol
Only muscarinic drugs
Muscarine
Pilocarpine
Bethanecol
Only Nicotinic drugs
Nicotine Succinylcholine (over stimulation-constant depolarisation- unresponsiveness)
AchI drugs
Neostigmine
Pyridostigmine
Edrophonium
Physostigmine(tertiary anime-naturally occurring)
Drugs that block nicotinic receptors in skeletal muscles
Tubocurarine
Other curare drugs
Block N receipts at ganglion
Trimethapan
Ach rarely used clinical why
- Oral administration- rapid hydrolysis
2. IV administration- rapid metabolism
treatment for postop/ neurogeni ileus and urinary retention
cholinergic drugs: bethanechol, carbachol
AchE inhibitors: neostigmine, pyridostigmine
used to diagnose type of myastina gravis and its features
small dose of Endophonium used to distinguish between chlinergic crisis and myastinic crisis (Tensilon Test)
- alcohol, quatinery amine
- do not enter CNS
- active for 5-15min only
Tx for MG
AchE inhi: pyridostigmine(mostly used), neostigmine
tx for glaucoma
cholinergic drug: pilocarpine(open-angled), carbachol
AchEI: physostigmine, echothiopate (topical only)
tx xerostmia
bethanechol
Bezold-Jerisch reflex
caused by high dose of nicotine
3 signs: hypotension, braycardia, nausea
lethal dose of nicotine
60mg
AchEI used in tx of alzheimer
drugs that can pass through BBB:
- donepezil
- tacrine
- revastigmine
- galatamine
ecothiopate
organophosphate
irreversible AchEI
release slowly from AchE- active for 2-7 days
malathion
organophsphate
not harmful- degraded by enzymes in mamals
used as ectoparasiticide in clinical setting
parathion
organophosphate
dangerous- ^ lipid solubility
active: 7-30 days
used in insecticides- toxicity in farmer
parlidoxime
- organophosphate antagonist
- oxime group has ^ affinity for the phosphorous
- tx patient with organophosphate poisoning
- does not enterCNS
- acts on both N and M receptors
- sideeffect: muscle weakness
- no effect after “aging”
aged organophosphate- AchE complex
strong irreversible covalent bond is formed
use of antimuscarinic drugs
- motion sickness (diarrihea)
- post-op urinary spam
- parkinsons disease
- antidote for parathion poisoning
other muscarinic functions
side effect of antimuscarinic drugs (state 8)
- xerostomia
- constipation
- urinary retention
- mydrasis
- percipitation glaucoma
- decrease sweating
- tachycardia
- hyperventilation and dec respiratory secretions
to block muscarinic action of following organs which receptors would you traget:
- CNS
- exocrine glands
- GIT
- Respiratory system
- eyes
- CVS
- Smooth muscles
- GUT
- several M receptors and effect depends on the dose
- M3, (M2)
- M1, M3( not sure)
- Nonselective
- M3
- M2
- (M2), M3
- M3, M1
featues of Atropine
- atropa belladona
- non selective competetive antagonist atM receptors
- tertiary amine
- distributed in CNS and other organs
- acts only on muscarinic ( hence cant inhibit muscle skeletal mucle contraction[N] cause with ^ Ach )
- excreted unchaged in urine
- t1/2= 2hr, active = 4-8hr
- in eye active for72hr
tissues most sensitive to atropine
- salivary glands
- bronchioles
- sweat glands
uses of atropne
- preanesthetic preparation-> dec resp secretions-> allow intubation
- ^ HR
- organphosphate poisoning
- mydrasis and cyloplegia
drugs that cause mydrastic and cyclopegic effects and duration of effect
tropicamide
ganglionic blockade on heart and blood vessels
tachycardia and vaso/venidilation
ganglionic blockade on respirtory
little effect of bronchodilation
ganglionic blockade on GIT
hypomotility, decrease serections, constipation
ganglionic blockade on GUT
urinary retention, impaired ejaculation
ganglionic blockade on iris/ ciliary muscles
mydrasis, cyclopegia
ganglionic blockade on glands
xerostomia, anhidrosis, dry eyes, dec gastric secretion
ganglionic blocing drugs
- hexamethonium [C6] (prototype ganglionic blocker)
- tetraethylammonium[TEA]
- decamethonium [C10]- depolarising blocker
- mecamylamine- cross BBB, absob orally, mental abberations
- trimethapan- low lipid soulubility, inactive orally, short t1/2, tx hypertension
non depolarizing anesthetics/NM blocker
competetive antagonist at Nm cause flacid paralysis 30-60mins
- tubocurarine
- cistracurium
- mivacurium
- pipecuronium
- rocuronium
- doxacurium
- pancuronium
- vecuronium
- atracurium
depolarising NM blockers/ anesthetic
cholinergic agonist->continuous depolarisation-> flacid paralysis, fasiculation and (after tx) muscel pain
- succinylcholine
- dexamethonium
tx malignant hyperthermia
succinylcholine
succinylcholine hydrolysed by
- butyrylcholinesterase or
2. pseudocholinesterase
- Skeletal muscles contain which receptor
Nm-> depolarization
β2 -> uptake of potassium (possible cause of skeletal muscle tremor not known for sure)
- Blood vessels of Skeletal muscles contain which receptor
β2 -> relaxation
Alpha -> contraction (less imp)
Some M3-> relaxation
drugs used as appetite suppressant/ weight loss
1.Phenylpropanolamine( can cause hemorrhage)
2. Ephedrine
3. Amphetamine
4.
Tx. Narcolepsy
- Modafinil
2. Ephedrine
Nasal decongestant
- Phenylephrine
- methoxamine
- NE
- Ephedrine
Tx ADHD
- Methylphenidate
2. Atomoxitine