Review of Pharmacology - 9E (2015)

Autonomic Nervous System
39. Ans. (b) Inhibition of nor-epinephrine release from adrenergic nerve endings (Ref: Goodman & Gilman 11/e p184-185;
KDT 6/e p96)
• Most of the blood vessels contain cholinergic M 3
receptors but no parasympathetic nerve supply.
• Exogenously administered ACh can stimulate M 3
receptors and result in vasodilation.
• Stimulation of M 3
receptors increases the production of NO (endothelium derived relaxing factor; EDRF) that
causes smooth muscle relaxation resulting in vasodilation.
• Vasodilation also may arise indirectly due to inhibition of NA release from nerve endings by ACh.
• If endothelium is damaged, ACh can stimulate receptors on vascular smooth muscle cells resulting in
vasoconstriction.
40. Ans. (d) Therapy with pralidoxime should ideally be monitored by measuring blood cholinesterase levels. (Ref: KDT
6/e p105, Drug facts and comparisons 2010/599)
• Pralidoxime is ACh esterase reactivator used for organophosphate poisoning.
• Blood cholinesterase levels can be used to monitor therapy, however RBC cholinesterase levels better reflect ACh
esterase activity than serum or plasma levels because with chronic exposure to organophosphates, serum levels may
return to normal but RBC levels remain depressed.
• Chlorinated pesticides like DDT are CNS stimulants and their overdose is treated by diazepam like drugs. Pralidoxime
has no role in their treatment.
• Nerve gases used in warfare act by inhibiting acetyl cholinesterase. Atropine and oximes are used for their treatment.
• When atropine and pralidoxime are used together, the signs of atropinization may occur earlier than might be expected
when atropine is used alone.
41. Ans. (a) Tacrine (Ref: KDT 6/e p104, 472, 473)
Because of hepatotoxicity, and requirement of frequent dosing, tacrine is less often used than other agents.
42. Ans. (b) Esteratic site of AChEs (Ref: KDT 6/e p99-100)
• The active region of Acetylcholinesterase (AChE) has two sites i.e. an anionic site and an esteratic site. Anticholinesterase
poisoning like Organophosphate compounds binds to esteratic site of AChE.
43. Ans. (b) Edrophonium (Ref: KDT 6/e p104)
• Drug used in ameliorative test (tensilon test) for myasthenia gravis is edrophonium. It is a cholinergic drug and can be
used for diagnosis of myasthenia gravis because of its short duration of action (10 – 30 min.)
44. Ans. (d) Is a competitive antagonist of acetylcholine (Ref: KDT 6/e p106)
Atropine acts as an antagonist at muscarinic receptors. It has no activity on nicotinic receptors and do not interfere with
the release of ACh.
45. Ans. (c) Malathion Poisoning (Ref: KDT 6/e p105)
• Pralidoxime is cholinesterase reactivator useful for organophosphate (malathion, parathion) poisoning.
46. Ans. (b) Opiates (Ref: KDT 6/e p102, 456)
Causes of Pin-Point Pupil
Autonomic General Pharmacology
Nervous System
• Opioids Poisoning
• Organophosphate Poisoning
• Carbamate Poisoning
• Carbolic acid Poisoning
• Pontine Hemorrhage
47. Ans. (c) Neostigmine (Ref: KDT 6/e p103)
48. Ans. (a) Pralidoxime (Ref: Katzung 11/e p121)
49. Ans. (b) Carbamate poisoning (Ref: Katzung 11/e p106-107)
50. Ans. (c) Rapidly destroyed in the body (Ref: Katzung 11/e p97)
51. Ans. (c) Acetylcholine (Ref: KDT 6/e p91)
52. Ans. (a) Edrophonium (Ref: KDT 6/e p101)
53. Ans. (c) Physostigmine (Ref: KDT 6/e p101)
54. Ans. (a) Physostigmine (Ref: KDT 6/e p102)
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