Phenelzine and tranylcypromine belong to which one of the following groups (class) of antidepressants

Correct Answer: B

Rationale: The correct answer is B: MAO inhibitors. Phenelzine and tranylcypromine are both monoamine oxidase inhibitors (MAOIs). MAOIs work by blocking the enzyme monoamine oxidase, which increases the levels of neurotransmitters such as serotonin, norepinephrine, and dopamine in the brain. This leads to an improvement in mood and alleviation of depressive symptoms. Tricyclic antidepressants (choice A) work by blocking the reuptake of neurotransmitters, 5-HT uptake inhibitors (choice C) specifically target serotonin reuptake, and atypical antidepressants (choice D) have various mechanisms of action different from MAOIs. Therefore, the correct choice is B as phenelzine and tranylcypromine are classified as MAO inhibitors.

Correct Answer: C

Rationale: Rationale: 1. Domperidone selectively blocks levodopa-induced vomiting by acting on peripheral dopamine receptors in the chemoreceptor trigger zone. 2. It does not cross the blood-brain barrier, hence does not interfere with levodopa's antiparkinsonian action. 3. Metoclopramide (A) can cross the blood-brain barrier and may diminish the therapeutic effects of levodopa. 4. Cisapride (B) is a prokinetic agent and does not have a specific antiemetic effect on levodopa-induced vomiting. 5. Ondansetron (D) is a serotonin receptor antagonist that targets different pathways and does not specifically address levodopa-induced vomiting.

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: Partial agonist at Mu receptor. Buprenorphine is a partial agonist at the Mu opioid receptor, meaning it activates the receptor to produce a partial response compared to a full agonist. This property allows for reduced risk of respiratory depression and overdose compared to full agonists. Choices B, C, and D are incorrect because buprenorphine does not act as a full agonist at either the Mu or Kappa receptors. It is important to understand the pharmacological properties of buprenorphine to optimize its use in clinical practice.

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.