AIM Exam Practice

Question:

A 27-year-old man receives a sympathomimetic during a pharmacology practical. The drug increases systolic pressure, lowers diastolic pressure and causes a rise in pulse pressure. Which receptor combination best explains this pattern?

Options:

Correct Answer: β₁ and β₂ stimulation

Explanation: β₁ stimulation raises cardiac output and systolic pressure, while β₂-mediated vasodilation lowers peripheral resistance and diastolic pressure.

Question:

A patient develops palpitations after receiving a drug that increases the concentration of endogenous noradrenaline in the synaptic cleft without acting primarily as a receptor agonist. Which mechanism best describes this action?

Options:

Correct Answer: Enhanced transmitter availability

Explanation: Indirect sympathomimetics increase the amount of endogenous catecholamine available at adrenergic synapses rather than directly activating receptors.

Question:

A sympathomimetic cannot be given effectively by mouth because it is rapidly inactivated in the intestinal wall and liver. Which chemical class most closely fits this pharmacokinetic behavior?

Options:

Correct Answer: Catecholamine sympathomimetic

Explanation: Catecholamines undergo rapid metabolism by COMT and MAO, producing poor oral bioavailability and a short duration of action.

Question:

A 54-year-old man receives an adrenergic drug that increases vascular resistance but has little direct action on the myocardium. His pulse slows after administration. Which drug profile best fits this observation?

Options:

Correct Answer: Predominant α₁ agonist

Explanation: α₁-mediated vasoconstriction raises arterial pressure, activating the baroreceptor reflex and producing reflex slowing of the heart.

Question:

A patient with severe bronchospasm receives a drug that relaxes bronchial smooth muscle by increasing intracellular cAMP. Which receptor is most closely linked with this therapeutic effect?

Options:

Correct Answer: β₂ receptor

Explanation: β₂ stimulation raises cAMP in bronchial smooth muscle, causing relaxation and bronchodilation.

Question:

A sympathomimetic increases contractility and conduction through the heart with comparatively little direct effect on bronchial smooth muscle. Which receptor is mainly responsible?

Options:

Correct Answer: β₁ receptor

Explanation: β₁ receptors are concentrated in the heart and increase rate, conduction and myocardial contractility.

Question:

A patient with an acute allergic reaction receives a drug that simultaneously constricts blood vessels, stimulates the heart and relaxes bronchial smooth muscle. Which pharmacological property permits this broad response?

Options:

Correct Answer: Combined α and β activity

Explanation: Broad activation of α₁, β₁ and β₂ receptors explains simultaneous vasoconstriction, cardiac stimulation and bronchodilation.

Question:

A 63-year-old patient receives a sympathomimetic that causes marked tachycardia together with a fall in peripheral vascular resistance. Which drug would best reproduce this hemodynamic pattern?

Options:

Correct Answer: Isoprenaline

Explanation: Isoprenaline activates β₁ and β₂ receptors, causing strong cardiac stimulation with peripheral vasodilation.

Question:

A pharmacology student observes that one adrenergic drug raises mean arterial pressure with little β₂-mediated vasodilation. Which receptor pattern best explains this response?

Options:

Correct Answer: α₁ with β₁ and little β₂ activity

Explanation: Strong α₁-mediated vasoconstriction with β₁ cardiac activity and minimal β₂ vasodilation is the characteristic receptor profile of noradrenaline.

Question:

A 45-year-old patient with severe systemic allergic reaction remains hypotensive and wheezy. Which additional property of adrenaline, apart from vasoconstriction and bronchodilation, helps support the circulation?

Options:

Correct Answer: Increase in cardiac contractility

Explanation: β₁ stimulation increases myocardial contractility and cardiac output, helping restore circulation during severe anaphylaxis.

Question:

During dopamine infusion, a patient initially demonstrates improved perfusion of selected vascular beds. With a higher infusion rate, cardiac output rises before marked peripheral vasoconstriction develops. Which sequence best describes the receptor progression?

Options:

Correct Answer: D₁ → β₁ → α₁

Explanation: Dopamine shows dose-dependent predominance from D₁ vascular effects to β₁ cardiac stimulation and then α₁ vasoconstriction.

Question:

A patient receiving a high infusion rate of dopamine develops cold extremities and increased systemic vascular resistance. Which change in receptor activity best explains this finding?

Options:

Correct Answer: Increasing α₁ activation

Explanation: At higher doses, dopamine increasingly stimulates α₁ receptors, causing peripheral vasoconstriction and increased systemic vascular resistance.

Question:

A patient with glaucoma is given a drug that lowers intraocular pressure by reducing secretion from the ciliary processes without producing an osmotic gradient. Which therapeutic principle is being used?

Options:

Correct Answer: Carbonic anhydrase inhibition

Explanation: Acetazolamide inhibits carbonic anhydrase in the ciliary processes, reducing aqueous humour production and lowering intraocular pressure.

Question:

A patient with a sudden marked rise in intraocular pressure requires rapid reduction of ocular water content. Which pharmacological approach acts through a plasma-to-eye osmotic gradient?

Options:

Correct Answer: Osmotic therapy with mannitol

Explanation: Mannitol increases plasma osmolarity and draws water out of ocular tissues, producing a rapid fall in intraocular pressure.

Question:

A patient with glaucoma receives an adrenergic agonist that lowers aqueous humour formation rather than producing mydriasis. Which receptor action is most consistent with this effect?

Options:

Correct Answer: α₂-receptor stimulation

Explanation: α₂ agonists such as brimonidine lower intraocular pressure mainly by reducing aqueous humour production.

Question:

A 48-year-old man taking an MAO inhibitor develops severe hypertension after consuming a fermented meal. The rise in blood pressure reflects excessive release of which endogenous transmitter?

Options:

Correct Answer: Noradrenaline

Explanation: Tyramine escapes MAO metabolism and promotes release of stored noradrenaline, producing intense vasoconstriction and hypertension.

Question:

A patient taking an MAO inhibitor is advised to avoid foods that undergo prolonged aging or fermentation. Which property of these foods is responsible for the interaction risk?

Options:

Correct Answer: High tyramine content

Explanation: Aged and fermented foods may contain substantial tyramine, which can precipitate severe hypertension during MAO inhibition.

Question:

A patient receiving an MAO inhibitor is accidentally given an indirectly acting sympathomimetic. Soon afterward, severe hypertension develops. Which pharmacological interaction best explains the toxicity?

Options:

Correct Answer: Enhanced catecholamine accumulation and release

Explanation: MAO inhibition decreases monoamine breakdown, while an indirect sympathomimetic increases catecholamine availability, producing excessive adrenergic stimulation.

Question:

A patient receives excessive adrenaline and develops severe hypertension with marked peripheral vasoconstriction. Which therapeutic strategy most directly reverses the dominant vascular receptor effect?

Options:

Correct Answer: α-adrenoceptor blockade

Explanation: Severe vasoconstriction from adrenaline excess is mainly α-mediated; an α antagonist such as phentolamine directly opposes this effect.

Question:

A patient receiving sympathomimetic therapy develops tremor, palpitations and marked elevation of blood pressure. Which general principle best explains the adverse-effect pattern?

Options:

Correct Answer: Excessive expression of normal adrenergic actions

Explanation: Sympathomimetic adverse effects are mainly extensions of expected receptor-mediated actions, including cardiac stimulation, tremor and vasoconstriction.