-
muscarinic in low dose
ganglionic stim in overdose (CV)
1st agent used in dentistry
- Pilocarpine
- 5-10mg 30 min b4 meal
- peak 1 hr
- duration 3-5 hr
- SE: sweating
- Contradindication: angle-closure glaucoma, iritis, uncontrolled asthma
-
mushroom poison
emesis, diarrhea, urination, cramps salivation, bradycardia, hypotention, bronchospasm, miosis
Muscarine
-
direct cholinomimetic
structurally unique
pharm action similar to pilocarpine
cevimeline
-
Increased secretions ¢Watery Saliva
Direct cardiac slowing
Bronchoconstriction
Increased GI propulsive activity
Increased micturition (urination)
Pupillary constriction
muscarinics (Parasympathetic agonists)
-
miosis
iris sphincter muscle contraction
-
parasympathetic ocular physiology
miosis, ciliary muscle contration (near vision), intraocular pressure reduced
-
What else other than pure parasympathetic actions do muscarinic agonists affect?
- hypotention: local vasodilation
- sweating: sympathetic muscarinic receptors
- metabolic inactivation: not ACHesterase
- Receptor selectivity
-
rx for (open-angle) glaucoma
- pilocarpine
- carbachol
- pupil constrict->increased aqueous flow out of anterior chamber-> decrease intraocular pressure
-
rx for Sjogrens xerostomia
- cevimeline
- 30mg TID
- 1.5 hr peak
- SE: sweating
- Contraindications: angle-closure glaucoma, acute iritis, uncontrolled asthma
-
Reversible AchE Inhibitors
- ->parasymp actions via increased Ach on muscarinic
- differences: prolonged, nicotinic activation (skeletal, CNS, symp)
- Edrophonium: reversible, short
- Physostigmine: lipid, central acting
- Neostigmine, pyridostigmine: reversible, slowly hydrolized
- Donepezil, galatamine, rivastigme: central, Alzheimers, dimentia
-
Irreversible AchE inhibitors
- Organophosphates
- Nerve gas: sarin, tabun
- Insecticides: malathion, parathion
- Therapeutic: echotiophate, isoflurophate (glaucoma eyedrops)
-
AchE inhibitor toxic rxns
- Muscarinic
- Ocular: miosis, blurred vision, headache
- Secretions: lacrimal, salivary, bronchial...
- Smooth muscle contraction: bronchial, visceral
- Cardiovascular: bradycardia, hypotension
- Nicotinic
- Skeletal muscle: fasciculation, weakness
- Cardiovascular: tachycardia, blood pressure instability
- CNS
- Mixed excitatory and depressant effects
- Respiratory and circulatory collapse
-
AchE Inhibitor rx for glaucoma
echothiophate
-
AchE Inhibitor rx for Alzheimer's
donepezil
-
AchE Inhibitor rx for myasthenia gravis
pyridostimine
-
AchE Inhibitor rx for atropine poisoning and central anicholinergic syndrome
physostimine
-
AchE Inhibitor rx for paralysis (neuromuscular block)
edrophonium, neostigmine
-
muscarinic blocker
atropine
-
organophosphate reversal agent
- pralidoxime
- binds to peripheral AchE to displace organophosphates
-
Which receptor aids erection?
M2: activates NO-> GTP cGMP vasodilation
-
PDE5 inhibitor
- -AFIL
- phosphodiesterase 5
- PDE5 degrades cGMP(vasodilates)
- Siladenafil
- Vardenafil
- Tadalafil
- SE: CYP3A4(erythromicin)
- potentiates nitroglycerine->profound hypotension
-
antimuscarinics (antisialogogues)
- Natural alkaloids (and derivatives)
- Atropine
- l-Hyoscyamine (Anaspaz)
- Scopolamine (Scopace, Transderm-Scop): CNS effects
- Synthetic quaternary ammonium drugs
- *Glycopyrrolate (Robinul)
- Propantheline (Pro-Banthine)
- Ipratropium (Atrovent)
*Glycopyrrolate is antisialogogue drug of choice (minimal CV effects)
-
drugs with anticholinergic effects
- Sedating Antihistamines
- e.g., diphenydramine (Benadryl)
- Tricyclic Antidepressants
- e.g., amitriptyline (Elavil), doxepin (Sinequan)
- Antipsychotics
- e.g, haloperidiol (Haldol), risperidone (Risperdal)
- Many Others
-
antimuscarinic for bronchospasm
ipratropium
-
antimuscarinic for bradycardia
atropine
-
antimuscarinic for meinere's disease and motion sickness
scoopolamine
-
antimuscarinic therapeutics
- Bronchospasm: ipratropium
- Bradycardia: atropine
- GI, GU hyperactivity: numerous antimuscarinics
- Hyperhydrosis: numerous antimuscarinics
- Meniere’s disease: scopolamine
- Motion sickness: scopolamine
- Ophthalmology: numerous antimuscarinics
- Parkinson’s disease: several antimuscarinics
- Anticholinesterase poisoning: atropine
-
antimuscarinic contraindications
- Closed angle (angle-closure) glaucoma
- Acute iritis
- Obstructive or paralytic GI or GU disease
- Myasthenia gravis
-
antimuscarinic side effects
- Xerostomia
- Hyperthermia in children
- Tachycardia with atropine
- Sedation/confusion with scopolamine
- Mydriasis, cycloplegia
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