#10 part 1+ mind maps. cholinomimetics. made by lama shatat corrected by laith sorour date 25/10

Transcription

1 #10 part 1+ mind maps cholinomimetics made by lama shatat corrected by laith sorour date 25/10

2 Cholinergic Cholinergic agonists Direct (activates directly Cholinergic Receptor) ANS drugs Antagonists Adrenergic indirect (CE inhibitor) Choline esters Natural alkaloid reversible *resist degradation *act directly on -Neostigmine by CE end organ like eye -Edrophonium *have longer -Pyridostigmine duration than Ach -Donepezil -Tacrine Ipilocarpin Bethanecol Carbacol Methacholin e BMC COL Direct Agonist Lowers high IOP in close angle & open angle chronic glaucoma Irreversible 1-Echothionophil 2-Isoflurophate(DPF) Choline esterase (CE): *protein *Metabolize ach to Choline & acetate *specific for Ach in cholinergic synapses Info: Inhibit reversibly CE enzyme Accumulation of Ach Electrostatic bonds Stimulate nicotinic & muscarinic receptors Useful in myasthenia gravis Organophosphorous compounds irreversibly inhibit CE Covalent bond in Enzymeinhibitor complex Used as insecticides: Parathion, Malathion As nerve gases in chemical warfare: Tabun, Sarin, Soman

3 Psuedocholine esterase: *found in plasma & liver * Not specific to Ach *Metabolizes other drugs (suxamethonium, procaine) Bethanecol Derivative of Ach Has: -Little nicotinic effects -Good muscarinic effects on bladder & GIT Carbacol Derivative of Ach *Has muscarinic & nicotinic actions *Limited use: -Because of nicotinic effects on ganglia & adrenal medulla pilocarpine *Natural plant alkaloid *Binds to muscarinic receptor *Resistant to CE enzyme *uncharged can enter Nervous system and cross BBB *makes tolerance Leads to easy urination & defecation Used to treat postoperative or post-labor: -Urinary retention or paralytic ileus: the weakness of intestine to push its content causing constipation because of weak peristaltic activity Used mainly topically as miotic(contract pupil) in glaucoma to decrease high intraocular pressure (IOP :it produces: -Miosis (contraction of circular muscle of iris) -Contraction of ciliary muscle of the eye -Reduction of IOP -Improves outflow of aqueous humour -Used topically in glaucoma -used in xerostomia(dry mouth) of sjornes syndrome (taken orally) *because stimulates salivation Note: What is glaucoma? Disease that occur because of increased pressure in the eye Side effects of Cholinomimetics: Excessive sweating, salivation Flushing, hypotension Abdominal colic & diarrhea Bronchospasm We use carbachol to reduce IOP in open-angle or narrow-angle glaucoma, particularly in patients who became tolerant to pilocarpine Pilocarpine-Impaired accommodation to far vision & darkness Improves outflow of aqueous humour: -Opens fluid pathway -Increase aqueous flow through canal of Schlemm -Secondary to contraction of circular muscle of the iris & ciliary muscle Contraindication of cholinomimetics: -to whom I shouldn t give them Bronchial asthma

4 -because the cholinergic drug will increase the contraction and will worsen the asthma Peptic ulcer a lesion in the lining (mucosa) of the digestive tract, typically in the stomach or duodenum, caused by the digestive action of pepsin and stomach acid *agonists will increase the secretion so you shouldn t give Ach & other cholinergic agonists Muscarinic Nicotinic CVS: 1)negative chronotropic intropic effect 2)decrease stroke volume & cardiac output 3)decrease ABP(arterial blood pressure) -stimulation of vascular M3 receptor -increase NO release from endothelium EYE: *Miosis: contraction of circular muscle of iris *accomolation to near vision *decrease IOP Defection *contraction of intestinal wall may lead to spasm and diarrhea *relaxation of sphinsters Autonomic ganglia -stimulation Adrenal medulla -increase NA & A NMJ -muscle contraction exocrine gland GI secretion: Increases Penile erection increase release of NO Bronchi *bronchoconstriction *increase mucosal secretion Urinitation *contraction of bladder wall *relaxation of sphincster

5 What is myasenthia gravis (MG)? Is a nerve muscular disease that leads to varying degrees of muscle weakness. The myasenthia disease autoimmune disease which result from antibodies that block Ach receptor (Nm) in the junction between muscle and nerve in NMJ Which lead to reduction of receptor number. symptoms and signs : -muscle weakness *because less Ach receptors work -fatigability -difficult speaking & swallowing *because the responsible for those processes are muscles What is cholinergic crisis? is an over stimulation at NMJ due to excess of Ach as a result of the inactivity of AchE enzyme which breaks down Ach *we see it in myasenthia gravis patients who take high dose of CEI\anticholinesterase drugs *over stimulation of nicotinic receptor(because of high concentration of Ach) will lead to blockage instead of further activation *symptoms & diagnosis: 1-muscle weakness 2-paralysis Treatment: 1-Thymectomy *removing of thymus gland 2-Immunosuppressant *its autoimmune diease so we lower the immunity 3-Reversible CEI *increases the number of Ach in the junction Reversible CEI: Inhibit reversibly CE enzyme Accumulation of Ach Electrostatic bonds -weak bonds so it is reversible Stimulate nicotinic & muscarinic receptors -because of the increased concentration of Ach Useful in myasthenia gravis

6 Neostigmine Pyridostigmine Edrophonium -Synthetic CEI similar similar -doesn t cross BBB -Duration of action : 4 hours -duration of action : 6 hours Duration of action: (10-20) min -Mainly MG treatment -Give orally,sc(subcutaneous) MG treatment given orally -diagnose MG -differentiate between weakness due to myasthenic crisis or cholinergic crisis -in treatment : 1-urinary retention 2-paralytic ileus 3-antidote to competitive NM blockers tobocurine poisoning Improvement MG Aggravated Cholinergic crisis Adverse effect of CEI: Excessive salivation Flushing and hypotension because of vasocontraction and decreased heart rate Abdominal colic and diarrhea -because of increased contraction of intestine and increased motility of GI Bronchospasm Alzheimer disease Tacrine Donepezil -Reversible CEI -New selective Reversible CEI -Used in Alzheimer disease -Used in Alzheimer disease -Once daily -Hepatotoxic -lacks hepatotoxicity -delay the progression of Alzheimer s disease, none can stop its progression. -GI distress is their primary adverse effect

7 Irreversible CEI used as organophosphorus compounds Nerve gases (chemical weapon\warfare) insecticides What is nerve gases? are class of phosphorous organic chemicals that disrupt the mechanism by which the nerve transfer messages to organs by Blocking CE Irreversibly by Covalent bonding in E-S complex this cause: 1-increased salivation 2-miosis of pupil 3- convulsion 4-involantary urination 5-death ex: Tabun, Sarin, Soman Are an organophosphate compounds. act on the CE indirectly ex: Tabun, Sarin, Soman Indirect irreversible agonists Isoflurophate (DFP) Echothiophate *irreversible CEI same *OP compound (organophosphate -new agent compound) *insecticide *topically in glaucoma *treatment of open-angle glaucoma Duration of action about a week Long Duration of action (week) *Toxicity: excessive cholinergic stimulation Organophosphate insectside poisoning: Agricultural or industrial accidents

8 essive cholinergic manifestations -because of CE inhibition -because increased motility and contraction of intestine -because of bronchial constriction n, excessive sweating, M. paralysis -point-pupil),convulsions&death OPI poisoning treatment General measures atropine IV or IM *cholinergic antagonist Diazepam for convulsions pralidoxime IM difference between direct & indirect cholinomimetics : : **Pharmacodynamics effects: -Similar **Central effects with indirect -Cross BBB Good Luck 0.o