An HIV-positive patient is hospitalized for evaluation of symptoms of progressive weakness, dyspnea, weight loss, and low-grade fever. A biopsy of lung tissue reveals Pneumocystis carinii pneumonia. This diagnosis means that the patient

Choice A reason:
Aspirin is an antiplatelet medication used to prevent blood clots in the arteries but is not the primary treatment for deep vein thrombosis (DVT), which is likely in this scenario. The patient's symptoms suggest a possible DVT, which requires anticoagulation therapy.

Choice B reason:
Clopidogrel (Plavix) is another antiplatelet medication, similar to aspirin, and is not the primary treatment for DVT. It is more commonly used to prevent clotting in arterial diseases such as coronary artery disease but not for venous thromboembolism.

Choice C reason:
Enoxaparin (Lovenox) is a low molecular weight heparin used for the initial treatment of DVT. It is an anticoagulant that helps prevent further clot formation and allows the body to break down the existing clot. Given the patient's symptoms, enoxaparin is the appropriate medication to anticipate for managing DVT.

Choice D reason:
Warfarin (Coumadin) is an oral anticoagulant used for long-term prevention of thromboembolism but is not typically used for initial DVT treatment due to its slow onset of action. Enoxaparin or other forms of heparin are preferred for immediate anticoagulation.

Choice A reason:
Metoprolol is a beta-blocker that primarily affects the heart by reducing heart rate and contractility. It does not specifically block the efflux of potassium. Beta-blockers are used to manage high blood pressure, angina, and certain arrhythmias, but they do not target potassium channels directly.

Choice B reason:
Amiodarone is an antiarrhythmic medication that blocks the efflux of potassium from cardiac cells. It prolongs the repolarization phase of the cardiac action potential by inhibiting potassium channels, which helps to stabilize cardiac rhythms and prevent arrhythmias. This mechanism makes amiodarone effective in treating various types of arrhythmias.

Choice C reason:
Lidocaine is a class IB antiarrhythmic that primarily blocks sodium channels in the heart. It is used to treat acute ventricular arrhythmias, especially after a myocardial infarction. While it affects the electrical activity of the heart, it does not specifically block potassium efflux.

Choice D reason:
Verapamil is a calcium channel blocker that primarily affects the influx of calcium into cardiac and smooth muscle cells. It is used to treat hypertension, angina, and certain arrhythmias, but it does not block potassium efflux.