Streptomycin has the following unwanted effect:

Correct Answer: D

Rationale: The correct answer is D because Streptomycin is known to cause ototoxicity and nephrotoxicity. Ototoxicity refers to the damage it can cause to the inner ear, leading to hearing loss and balance issues. Nephrotoxicity refers to its potential to harm the kidneys. The other choices are incorrect because cardiotoxicity (A) and hepatotoxicity (B) are not typically associated with Streptomycin use. Retrobulbar neuritis with red-green color blindness (C) is a side effect of Ethambutol, not Streptomycin.

Correct Answer: B

Rationale: The correct answer is B: Blockade of Na+ channels in the collecting duct. Triamterene is a potassium-sparing diuretic that works by inhibiting the epithelial sodium channels (ENaC) in the collecting duct of the nephron. By blocking these channels, triamterene reduces sodium reabsorption, leading to decreased potassium excretion. This mechanism helps maintain potassium levels in the body, making it an effective treatment for conditions like systolic cardiac failure where potassium loss is a concern. Summary: A: Enhancement of K+ reabsorption in the proximal tubule - This is incorrect as triamterene does not act on the proximal tubule for potassium-sparing effects. C: Enhancement of K+ reabsorption in the loop of Henle - This is incorrect as triamterene does not primarily affect potassium reabsorption in the loop of Henle. D: Blockade of aldosterone receptors in the collecting duct - This is

Correct Answer: C

Rationale: The correct answer is C: Demeclocycline. It is the most appropriate choice for the patient's condition due to its ability to treat syndrome of inappropriate antidiuretic hormone secretion (SIADH), characterized by excessive release of antidiuretic hormone causing water retention. Demeclocycline acts as a competitive antagonist of ADH, helping to correct the water imbalance. Desmopressin (A) is a synthetic form of ADH and would exacerbate the condition. Hydrochlorothiazide (B) and Amiloride (D) are diuretics that would further worsen the water imbalance in SIADH by increasing urine output.

Correct Answer: A

Rationale: In this question, the correct answer is A) Moxonidine. Moxonidine is a selective agonist of the imidazoline receptor, specifically the I1 subtype. This receptor is involved in the regulation of blood pressure and cardiovascular function. Moxonidine acts centrally to decrease sympathetic outflow, leading to vasodilation and reduced blood pressure. Option B) Dexmedetomidine is a selective agonist of the α2-adrenergic receptor and is commonly used as a sedative in intensive care settings. While it does have some effects on blood pressure regulation, it does not act on imidazoline receptors. Option C) Tizanidine is a centrally acting alpha-2 adrenergic agonist primarily used as a muscle relaxant. It does not target imidazoline receptors. Therefore, the correct answer is A) Moxonidine because it specifically targets the imidazoline receptor, while the other options act on different receptors with distinct physiological effects. Understanding the specific mechanisms of action of cardiovascular drugs is crucial for healthcare professionals to make informed decisions when managing patients with cardiovascular conditions.

Correct Answer: C

Rationale: Rationale: The correct answer is C) Cumulative poisoning. Digitalis, a medication derived from the foxglove plant, is commonly used to treat various heart conditions like heart failure and atrial fibrillation. Overuse of digitalis can lead to cumulative poisoning due to its narrow therapeutic index, meaning there is a fine line between a therapeutic dose and a toxic dose. Option A) Habituation refers to the body's decreased response to a drug over time, requiring higher doses to achieve the same effect. This is not the case with digitalis. Option B) Tolerance occurs when the body becomes accustomed to a drug's effects, also leading to the need for higher doses to achieve the same response. However, digitalis toxicity is more about the drug building up in the body to toxic levels rather than tolerance development. Option D) Physical dependence is a state where the body adapts to a drug and requires it to function normally. Digitalis toxicity is not primarily about physical dependence but rather the toxic effects of the drug accumulating in the body. Educational Context: It is crucial for healthcare professionals to understand the potential risks associated with medications like digitalis to prevent adverse effects such as cumulative poisoning. Monitoring patients closely, conducting regular drug level checks, and educating patients on signs of toxicity are essential in managing cardiovascular drug therapy effectively. Understanding the mechanisms of drug actions and potential side effects is vital for safe and effective patient care.