Muscarinic receptors can be stimulated by the following drugs EXCEPT:

Correct Answer: B

Rationale: The correct answer is B: Hyoscine. Muscarinic receptors can be stimulated by Pilocarpine, Acetylcholine, and Neostigmine, as they are known agonists of muscarinic receptors. Hyoscine, also known as scopolamine, is an antagonist of muscarinic receptors, blocking their stimulation. This makes it the exception among the listed drugs.

Correct Answer: D

Rationale: Propranolol is a non-selective beta-blocker which primarily affects the heart. Bronchodilation is not a common effect of propranolol due to its non-selectivity for beta-2 receptors in the lungs. Therefore, choice D is the correct answer. Choices A, B, and C are correct because propranolol typically causes negative inotropic effect (reduced force of heart contraction), negative chronotropic effect (slowing of heart rate), and slowing of A-V conduction (delay in electrical signal between atria and ventricles), respectively.

Correct Answer: C

Rationale: Certainly! Bethanechol is a muscarinic agonist that specifically targets the bladder and bowel smooth muscles, improving their tone and contractility. It is used for conditions like atonic bowel or bladder dysfunction. Clonidine is an alpha-2 adrenergic agonist, Chlorpromazine is a typical antipsychotic, and Ephedrine is a sympathomimetic amine used for decongestion and bronchodilation. These medications do not have the same mechanism of action or target as Bethanechol and are not indicated for atonic bowel or bladder issues.

Correct Answer: C

Rationale: The correct answer is C: Bronchodilation. Beta-blockers primarily work by blocking the beta-adrenergic receptors, leading to a decrease in heart rate and contractility. This can result in adverse effects such as hypotension, heart failure, and heart block due to the reduced cardiac output. However, bronchodilation is not a typical adverse effect of beta-blockers. In fact, beta-blockers can cause bronchoconstriction in patients with underlying respiratory conditions like asthma, making choice C the correct answer. Choices A, B, and D are incorrect because hypotension, heart failure, and heart block are known adverse effects associated with beta-blockers due to their mechanism of action on the cardiovascular system.

Correct Answer: C

Rationale: The correct answer is C: Propranolol. Verapamil is a calcium channel blocker that can depress heart rate and contractility. Propranolol is a beta-blocker that also decreases heart rate and contractile force. When combined, both drugs can have an additive effect leading to a significant decrease in heart rate and contractility, potentially causing bradycardia or heart failure. Albuterol (A) is a beta-2 agonist that actually increases heart rate and contractility. Scopolamine (B) is an anticholinergic drug that may decrease heart rate, but its effect is not as significant as propranolol. Isoproterenol (D) is a beta agonist that increases heart rate and contractility, so its combination with verapamil would not pose the same risk as propranolol.