Intravenous administration of epinephrine to a patient results in a severe decrease in diastolic pressure and an increase in cardiac output. Which of the following drugs might the patient have previously taken that could account for this unexpected effect?

Correct Answer: D

Rationale: The correct answer is D: Prazosin. Prazosin is an alpha-1 adrenergic receptor antagonist, which blocks the vasoconstrictor effect of catecholamines like epinephrine, leading to vasodilation and a decrease in diastolic pressure. The unexpected effect of a decrease in diastolic pressure and an increase in cardiac output after epinephrine administration suggests that the patient might have taken a drug that blocks alpha-1 receptors. Propranolol (A) is a beta-blocker, which would not cause this effect. Atropine (B) is a muscarinic receptor antagonist and would not explain the observed effects. Phenylephrine (C) is an alpha-1 agonist, so it would not result in the described response. Therefore, Prazosin (D) is the most likely drug the patient previously took to account for the unexpected effects of epinephrine administration.

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: C

Rationale: The correct answer is C: Pilocarpine. Parasympatholytic drugs inhibit the parasympathetic nervous system. Pilocarpine, on the other hand, is a parasympathomimetic drug that stimulates the parasympathetic nervous system. Hyoscine, Atropine, and Ipratropium are all parasympatholytic drugs that block the effects of the parasympathetic nervous system. Therefore, pilocarpine is the exception in this list.

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.