Salbutamol is used to treat:

Correct Answer: B

Rationale: Salbutamol is a beta2-adrenergic agonist that relaxes smooth muscles in the airways, making it an effective treatment for bronchial asthma by relieving bronchospasm and improving airflow. It is not used for angina pectoris, hypertension, or cardiac arrhythmias as these conditions do not involve bronchial constriction.

Correct Answer: D

Rationale: The correct answer is D: Tropicamide. Tropicamide is a short-acting cycloplegic and mydriatic drug commonly used in ophthalmology. It acts quickly, providing temporary dilation of the pupil and relaxation of the ciliary muscle for refraction assessment. Atropine (A) is a long-acting cycloplegic, not short-acting. Homatropine (B) and Hyoscine (C) are also longer-acting drugs compared to Tropicamide. Therefore, D is the correct answer for its rapid onset and short duration of action in dilating the pupil and paralyzing accommodation.

Correct Answer: D

Rationale: The correct answer is D: Beta-adrenergic antagonists. Beta-blockers can mask the typical signs and symptoms of hypoglycemia such as tremors, palpitations, and sweating by inhibiting the adrenergic response to low blood sugar levels. Other choices (A, B, C) are incorrect as they do not have the same mechanism of action in masking hypoglycemic reactions in diabetic patients.

Correct Answer: C

Rationale: The correct answer is C: Phenylephrine. Phenylephrine is a sympathomimetic drug that stimulates the sympathetic nervous system, leading to vasoconstriction and increased heart rate. In contrast, choices A, B, and D all work to depress sympathetic activity by different mechanisms. Clonidine is an alpha-2 adrenergic agonist that decreases sympathetic outflow. Reserpine inhibits the storage of norepinephrine, leading to decreased sympathetic activity. Labetalol is a non-selective beta blocker that blocks beta-adrenergic receptors, reducing sympathetic effects. Therefore, Phenylephrine is the only drug among the options that does not depress sympathetic activity.

Correct Answer: C

Rationale: Cocaine blocks the reuptake of noradrenaline from adrenergic nerves, leading to excessive stimulation of adrenergic receptors. This causes increased blood pressure, which can result in a hypertensive crisis or stroke. Additionally, the vasoconstrictive effects of excess noradrenaline can lead to tissue damage in the nose when cocaine is inhaled frequently. Choices A and B are incorrect because cocaine does not directly block alpha adrenergic or muscarinic receptors. Choice D is incorrect because cocaine does not deplete norepinephrine from adrenergic nerve endings but rather increases its concentration by blocking reuptake.