Which opioid analgesic provides symptomatic relief of pain, cough, and diarrhea?

Correct Answer: C

Rationale: The correct answer is C: Both Morphine and Codeine. Opioids like morphine and codeine act on opioid receptors in the brain and spinal cord to provide pain relief, suppress cough reflex, and slow down gut motility to relieve diarrhea. Morphine is a potent opioid used for moderate to severe pain, while codeine is a milder opioid often used for mild to moderate pain. Both drugs are known to provide relief for pain, cough, and diarrhea due to their shared pharmacological actions on the body. Therefore, the correct choice is C as both morphine and codeine are effective in providing symptomatic relief for pain, cough, and diarrhea. Choices A, B, and D are incorrect as they do not accurately reflect the pharmacological properties of opioids like morphine and codeine in providing relief for these specific symptoms.

Correct Answer: A

Rationale: The correct answer is A: Prostaglandins. Prostaglandins are most associated with labor as they play a key role in promoting uterine contractions. They are synthesized in the uterus and stimulate smooth muscle contractions, leading to the initiation and progression of labor. Thromboxanes primarily regulate platelet function and vasoconstriction, not uterine contractions. Leukotrienes are involved in inflammatory responses and immune regulation, not specifically labor. NSAIDs inhibit prostaglandin synthesis, which can hinder labor progression, making them an unlikely choice for promoting uterine contractions.

Correct Answer: D

Rationale: The correct answer is D because the first pass effect refers to the amount of drug that is lost due to hepatic metabolism when a drug is absorbed from the gastrointestinal tract after oral administration. This process occurs before the drug reaches systemic circulation, reducing the bioavailability of the drug. Option A is incorrect as hepatic artery does not eliminate the drug. Option B is incorrect as it refers to drug excretion via stool. Option C is incorrect as it refers to drug destruction by stomach acidity, not hepatic metabolism.

Correct Answer: D

Rationale: The correct answer is D because drugs exhibiting zero-order kinetics have a linear plot of drug concentration versus time. In zero-order kinetics, the rate of drug elimination remains constant regardless of drug concentration, leading to a linear decrease in drug concentration over time. Choice A is incorrect as first-order kinetics are more common. Choice B is incorrect as zero-order kinetics show a constant rate of elimination, not exponential decrease. Choice C is incorrect as the half-life of drugs exhibiting zero-order kinetics is dose-dependent.

Correct Answer: A

Rationale: The correct answer is A because highly bound drugs (98% bound) do not have clinically significant drug-drug interactions through displacement from binding sites on plasma proteins. This is because only the unbound (free) fraction of a drug is pharmacologically active and available for interactions. Highly bound drugs are bound to proteins and not readily available for interactions. Regarding the other choices: B: Only free drugs can pass through glomerular filtration - Correct, as only unbound drugs can be filtered through the kidneys. C: Only free drugs become available for hepatic metabolism - Correct, as only unbound drugs can undergo metabolism in the liver. D: Only free drugs can distribute to peripheral tissues - Correct, as only unbound drugs can leave the bloodstream and reach peripheral tissues.