Antitussive agents should be used with caution in patients who have a history of addiction.

Choice A rationale

Beta-adrenergic blockers generally do not decrease urinary output. These drugs primarily act on the cardiovascular system by blocking beta-adrenergic receptors, which results in lowered heart rate and blood pressure. Their effects are less pronounced on the renal system unless specific agents with renal effects are used.

Choice B rationale

Beta-adrenergic blockers decrease the strength of heart muscle contraction (negative inotropic effect). By blocking beta receptors, they inhibit the stimulatory effects of catecholamines on the heart, reducing the force of myocardial contraction, which helps decrease oxygen demand and control angina symptoms.

Choice C rationale

Beta-adrenergic blockers typically decrease heart rate (negative chronotropic effect) rather than increase it. They inhibit beta-adrenergic receptors, which leads to a slower heart rate and can help manage conditions like angina by reducing myocardial oxygen consumption.

Choice D rationale

Beta-adrenergic blockers decrease oxygen consumption by reducing heart rate and the force of contraction. These effects lower myocardial oxygen demand, which is beneficial for patients with angina by preventing episodes triggered by increased oxygen needs.

Choice A rationale

True. Xanthine derivatives like theophylline can cause serious adverse effects, including brain damage, when blood levels become too high. It is critical to monitor theophylline levels to prevent toxicity and associated neurological complications.

Choice B rationale

False. If xanthine levels remain within therapeutic ranges, the risk of brain damage is minimized. However, this statement is incorrect as it does not acknowledge the potential severity of the adverse effects linked to elevated theophylline levels.