Which of the following medications is most commonly used for the treatment of osteoarthritis pain?

Correct Answer: C

Rationale: The correct answer is C: Celecoxib. Celecoxib is commonly used for osteoarthritis pain as it is a nonsteroidal anti-inflammatory drug (NSAID) that helps reduce inflammation and pain. It specifically targets the COX-2 enzyme, which is involved in the inflammatory process in osteoarthritis. Methotrexate (A) is used for rheumatoid arthritis, not osteoarthritis. Acetaminophen (B) is a mild pain reliever and is commonly used for osteoarthritis pain, but not as frequently as NSAIDs like celecoxib. Prednisone (D) is a corticosteroid that may be used for short-term relief of osteoarthritis symptoms but is not typically the first-line treatment due to potential side effects.

Correct Answer: A

Rationale: Step 1: Hydrochlorothiazide is a thiazide diuretic. Step 2: Thiazide diuretics work by inhibiting sodium reabsorption in the kidneys. Step 3: By blocking sodium reabsorption, hydrochlorothiazide increases water excretion, reducing blood volume and lowering blood pressure. Step 4: Therefore, the correct answer is A: Inhibiting sodium reabsorption in the kidneys. Summary: - Option B (Blocking calcium channels) is incorrect because hydrochlorothiazide does not affect calcium channels. - Option C (Increasing the excretion of potassium) is incorrect as thiazide diuretics can cause hypokalemia by increasing potassium excretion. - Option D (Relaxing vascular smooth muscle) is incorrect as this is not the primary mechanism of action of hydrochlorothiazide.

Correct Answer: C

Rationale: Step 1: Beta-blockers block the effects of adrenaline on beta receptors in the heart. Step 2: Adrenaline (epinephrine) binds to beta receptors in the heart, leading to increased heart rate and contractility. Step 3: By blocking beta receptors, beta-blockers reduce heart rate and contractility. Step 4: This reduces the workload on the heart, improves efficiency, and helps in managing heart failure. Summary: A: Incorrect. Beta-blockers actually decrease heart rate and contractility. B: Incorrect. Beta-blockers primarily affect heart function, not preload and afterload. D: Incorrect. Beta-blockers do not directly increase cardiac output; they improve heart function by reducing workload.

Correct Answer: B

Rationale: The correct answer is B: Increasing serotonin and norepinephrine in the brain. Tramadol is a synthetic opioid analgesic that acts by binding to mu-opioid receptors and also inhibiting the reuptake of serotonin and norepinephrine. This dual mechanism of action helps alleviate pain by enhancing the effects of these neurotransmitters in the brain. Choices A, C, and D are incorrect because tramadol primarily affects serotonin and norepinephrine levels rather than blocking opioid receptors, inhibiting dopamine reuptake, or decreasing substance P in the spinal cord.

Correct Answer: C

Rationale: Rationale for Choice C: In noncompetitive antagonism, the antagonist binds irreversibly to a site different from the agonist binding site, preventing agonist binding. Increasing agonist concentration cannot overcome this as the antagonist blocks the receptor irreversibly. This results in a fixed maximum response. Summary: A: Incorrect. The potency of the drug may change due to noncompetitive antagonism. B: Incorrect. Noncompetitive antagonism does not affect the number of receptors available to bind the agonist. D: Incorrect. Choice C is correct, making this statement wrong.