Which of the following is considered a class IA Sodium Channel blocker?

Correct Answer: D

Rationale: The correct answer is D: Procainamide. Procainamide is a class IA antiarrhythmic drug that blocks sodium channels, prolonging the action potential duration. This helps to stabilize the heart's rhythm. Mexiletine (A) is a class IB antiarrhythmic drug that blocks sodium channels with fast recovery kinetics. Amiodarone (B) is a class III antiarrhythmic drug that prolongs repolarization by blocking potassium channels. Quinidine (C) is a class IA antiarrhythmic drug that also blocks sodium channels, but it is not a class IB sodium channel blocker like Procainamide.

Correct Answer: D

Rationale: The correct answer is D: Procainamide. Procainamide is a class IA antiarrhythmic drug that blocks sodium channels, prolonging the action potential duration. This helps to stabilize the heart's rhythm. Mexiletine (A) is a class IB antiarrhythmic drug that blocks sodium channels with fast recovery kinetics. Amiodarone (B) is a class III antiarrhythmic drug that prolongs repolarization by blocking potassium channels. Quinidine (C) is a class IA antiarrhythmic drug that also blocks sodium channels, but it is not a class IB sodium channel blocker like Procainamide.

Correct Answer: B

Rationale: The correct answer is B: Quinidine. Cinchonism is a condition caused by the toxicity of Cinchona alkaloids, which are found in drugs like quinine and quinidine. Quinidine is specifically known to cause symptoms of cinchonism such as tinnitus, headache, blurred vision, and nausea. Valproic acid (choice A) is an anticonvulsant, not associated with cinchonism. Isoniazid (choice C) is an antibiotic used to treat tuberculosis and does not cause cinchonism. Ethosuximide (choice D) is an anticonvulsant used to treat absence seizures and is not linked to cinchonism.

Correct Answer: B

Rationale: The correct answer is B: Diarrhea. Atropine, a cholinoreceptor blocker, inhibits acetylcholine, causing decreased GI motility leading to constipation. Atropine also increases pulse rate due to reduced vagal tone (A). It causes mydriasis by blocking cholinergic receptors in the eye (D). Diarrhea is not a typical side effect of atropine due to its anticholinergic properties.

Correct Answer: B

Rationale: Prednisone is a corticosteroid used to treat inflammatory conditions and certain types of cancer. Testicular cancer is not typically treated with Prednisone because it is a form of cancer that requires specific treatments such as surgery, chemotherapy, or radiation therapy. Prednisone is not the primary treatment option for testicular cancer. In contrast, Prednisone is commonly used to manage symptoms in conditions like Cushing's disease, lymphomas, and chronic leukemias by reducing inflammation and suppressing immune response. Therefore, choice B is the correct answer as Prednisone is not a standard treatment for testicular cancer.

Correct Answer: B

Rationale: The correct answer is B: Liver. Warfarin is primarily metabolized in the liver by the cytochrome P450 enzyme system. The liver is responsible for breaking down and activating many drugs, including Warfarin. It is where the drug's metabolism and effects are most significant. The other choices are incorrect because Warfarin's main site of activity is in the liver, not the kidney, blood, or heart. The kidney mainly excretes the drug, while the blood carries it throughout the body, and the heart is not directly involved in Warfarin's metabolism.

Correct Answer: C

Rationale: The correct answer is C: Tetracycline. Tetracycline is associated with extreme photosensitivity due to its mechanism of action causing phototoxic reactions when exposed to sunlight. Digitalis (A) is a cardiac medication, niacin (B) is a B vitamin, and fluoroquinolones (D) are antibiotics, none of which are known to cause extreme photosensitivity reactions.

Correct Answer: B

Rationale: The correct answer is B: ACE inhibitor. Drugs ending in the suffix (-pril) typically refer to ACE inhibitors, which are commonly used to treat hypertension and heart failure by inhibiting the angiotensin-converting enzyme. ACE inhibitors do not belong to the categories mentioned in the other choices. Choice A (H) is vague and does not provide any relevant information. Choice C (Antifungal) is incorrect as drugs ending in (-pril) are not typically used to treat fungal infections. Choice D (Beta agonist) is also incorrect as drugs ending in (-pril) do not belong to the class of beta agonists, which are used to treat conditions like asthma and COPD.

Correct Answer: D

Rationale: Nifedipine is a calcium channel blocker primarily used to treat angina, arrhythmias, and hypertension due to its vasodilatory effect. However, it does not treat fluid retention as it does not have diuretic properties. Therefore, the correct answer is D. Choice A, B, and C are incorrect because nifedipine is commonly used to manage these conditions.