Which of the following drugs is a direct stimulant of β1 and β2 adrenoceptors:

Correct Answer: B

Rationale: The correct answer is B: Isoprenaline. Isoprenaline directly stimulates both β1 and β2 adrenoceptors. It is a non-selective β-adrenergic agonist, leading to increased heart rate (β1 stimulation) and bronchodilation (β2 stimulation). Incorrect choices: A: Noradrenaline mainly acts on α-adrenoceptors. C: Salbutamol is a selective β2 agonist, not stimulating β1 receptors. D: Amphetamine primarily acts on catecholamine release and reuptake inhibition, not direct β-adrenoceptor stimulation.

Correct Answer: C

Rationale: The correct answer is C: Hypotension. Chronic tobacco smoking typically causes vasoconstriction, leading to increased blood pressure rather than hypotension. Peripheral vascular disease (A), cardiac arrhythmias (B), and increased gastric secretion (D) are common effects of chronic tobacco smoking due to the harmful impact on blood vessels, heart function, and gastrointestinal system.

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.