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Pharm - Ch. 15
Cholinesterase Inhibitors
| Question | Answer |
|---|---|
| Cholinesterase inhibitors are what type of agonist? | Indirect-acting cholinergic agonists |
| When ACh accumultates in synapses, what type of receptors are activated? | Muscarinic, nictonic in ganglia, NMJ, cholinergic in CNS |
| Which type of ChE inhibitor produces long lasting effects? | Irreversible inhibitors |
| What is the major indication for ChE inhibitors? | Myasthenia gravis |
| What is the name of a well-known, reversible ChE inhibitor? | Neostigmine |
| Which receptors does neostigmine affect? | mAChR and nicotinicM |
| List the muscarinic responses associated with neostigmine | Muscarinic: increased gland secretions, increased tone/motility of GI smooth muscle, urinary urgency, bradycardia, bronchial constriction, miosis, focusing of lens for near vision |
| When given at toxic dose, neostigmine ___ the force of contraction on skeletal muscles | Reduce |
| When given at therapeutic dose, neostigmine ___ the force of contraction on skeletal muscles | Increase |
| Why is contractile force reduced when neostigmine is given in toxic doses? | Excessive amounts of ACh at NMJ keep motor plate in constant depolarization, stopping the signal for calcium release, reducing contraction. |
| Can neostigmine cross membranes? | No, because it has positive charge. It cannot easily pass GI, blood-brain, or placenta as result. |
| Reversible ChE inhibitors can be used for what besides myasthenia gravis? | Reversal of nondepolarizing neuromuscular blockade and poisoning by muscarinic antagonists |
| What is a cholinergic crisis? | Depolarizing neuromuscular blockade with signs of excessive muscarinic stimulation r/t overdose on ChE inhibitors. Death results from respiratory depression |
| What is used to treat reversible ChE inhibitor poisoning? | Atropine and mechanical ventilation |
| What is myasthenia gravis? | Neuromuscular disorder characterized by fluctuating muscle weakness and rapid fatigue. |
| What causes symptoms in MG? | Antibodies attack nicotinicM receptors on skeletal muscle, leading to weakness |
| How do ChE inhibitors treat MG? | Prevent ACh inactivation, causing effects of ACh released from motor neuron to intensify and increase muscle strength. |
| What is the distinction between myasthenic crisis and cholinergic crisis? | Myasthenic crisis can be relieved by ChE inhibitor while cholinergic crisis would cause symptoms to intensify. |
Created by:
choel
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