Which of the following drugs has potent antiandrogenic and weak progestational activity?

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: A

Rationale: The correct answer is A: Cyclic adenosine monophosphate (cAMP) synthesis. Oxytocin induces uterine contractions during labor by binding to its receptor and activating the G-protein coupled receptor, leading to increased cAMP synthesis. This results in the activation of protein kinase A, which ultimately leads to smooth muscle contraction in the uterus. Phosphoinositide hydrolysis (choice B) is not involved in oxytocin signaling. Cyclic guanosine monophosphate (cGMP) synthesis (choice C) is typically associated with nitric oxide signaling, not oxytocin. Tyrosine residue phosphorylation (choice D) is more related to growth factor signaling pathways, not oxytocin-induced labor contractions.

Correct Answer: D

Rationale: The correct answer is D: Octreotide. This drug is appropriate for the patient as it helps manage symptoms of carcinoid syndrome while waiting for radiotherapy to take effect. Octreotide is a somatostatin analog that inhibits the release of various hormones, providing symptom relief. Leuprolide (A) is a gonadotropin-releasing hormone agonist used for hormone-related cancers, not specifically for symptom management. Cosyntropin (B) is a synthetic adrenocorticotropic hormone used for diagnosing adrenal insufficiency. Somatropin (C) is human growth hormone used for growth disorders, not symptom management in cancer patients.

Correct Answer: D

Rationale: The correct answer is D: Cell nucleus. Levothyroxine acts by binding to thyroid hormone receptors in the cell nucleus, where it regulates gene expression. This is essential for controlling metabolism and energy production. Choices A, B, and C are incorrect because levothyroxine's mechanism of action does not involve the cell membrane, mitochondria, or smooth endoplasmic reticulum. The nucleus is where genetic material is stored and gene expression is controlled, making it the main site of action for levothyroxine.

Correct Answer: A

Rationale: The correct answer is A: Disorientation and lethargy. Inappropriate increase of drug dose can lead to drug toxicity, resulting in central nervous system depression. Disorientation and lethargy are common signs of CNS depression. Shallow breathing (choice B) may indicate respiratory depression, but it typically occurs after severe drug overdose. Unconsciousness (choice C) is a more severe manifestation that may occur after prolonged CNS depression. Severe pain in both legs (choice D) is unlikely to be directly related to drug overdose but may indicate an unrelated condition.