Answer: A. 1-R, 2-S, 3-P, 4-Q

Explanation: Based on the answer key: carvedilol exhibits NO-mediated vasodilation (R); nebivolol works as a non-selective blocker with additional properties (S); atenolol is a β1 antagonist (P); pindolol is a mixed receptor blocker (Q).

Answer: D. Cyclophosphamide

Explanation: Cyclophosphamide is a prodrug that requires metabolic activation by hepatic cytochrome P450 enzymes to generate its active alkylating species.

Answer: D. Doxazosin

Explanation: Doxazosin is a selective α-1 antagonist that is used to treat conditions like hypertension and benign prostatic hyperplasia by relaxing vascular smooth muscle.

Answer: D. All of the above

Explanation: An inverse agonist not only blocks a receptor but also reduces its basal activity; examples include certain betacarbolines, some cannabinoids, and yohimbine.

Answer: A. Inositol triphosphate

Explanation: Inositol triphosphate (IP₃) is a key second messenger that binds to its receptor on the endoplasmic reticulum, causing the release of stored Ca²⁺ into the cytoplasm.

Answer: A. Myasthenia gravis

Explanation: The autoimmune destruction of nicotinic receptors on the neuromuscular junction is the basis for myasthenia gravis, causing muscle weakness.

Answer: C. Terminalia arjuna

Explanation: Terminalia arjuna has long been used in Ayurvedic medicine for its cardioprotective properties, including improving cardiac contractility and reducing heart failure symptoms.

Answer: D. Copper, gold, lead, and mercury

Explanation: Penicillamine chelates heavy metals such as copper, gold, lead, and mercury, making it useful as an antidote in poisoning cases involving these metals.

Answer: C. Flutamide

Explanation: Flutamide is an antiandrogen used in the treatment of prostate cancer; it works by antagonizing the androgen receptor, thereby inhibiting hormone-driven tumor growth.

Answer: A. Streptomycin

Explanation: Streptomycin binds to the 30S ribosomal subunit, blocking the A site and thereby inhibiting protein synthesis in bacteria.

Answer: C. Zolpidem

Explanation: Zolpidem selectively binds to the benzodiazepine receptor subtype involved in sleep regulation, producing hypnotic effects with fewer side effects than nonselective benzodiazepines.

Answer: D. Progesterone antagonist

Explanation: Mifepristone acts as a progesterone receptor antagonist and is used for medical termination of pregnancy by blocking the action of progesterone.

Answer: D. Reduction of circulating active TNF-α levels

Explanation: Etanercept is a TNF-α inhibitor; it works by binding to and neutralizing circulating TNF-α, thereby reducing inflammation in rheumatic conditions.

Answer: D. Ropivacaine

Explanation: Ropivacaine is recognized for its lower cardiotoxicity compared to similar local anesthetics, making it a safer option for regional anesthesia.

Answer: D. Pilocarpine

Explanation: Pilocarpine is a lipid-soluble cholinomimetic agent that can penetrate ocular tissues to stimulate muscarinic receptors, thereby reducing intraocular pressure in glaucoma.

Answer: D. Act by decreasing insulin resistance

Explanation: Meglitinides stimulate insulin secretion rather than decreasing insulin resistance; they are used to reduce postprandial blood glucose with a lower risk of hypoglycemia compared to sulfonylureas.

Answer: A. 5HT1D agonist

Explanation: 5HT1D agonists, such as triptans, are used to abort migraine attacks by causing vasoconstriction of intracranial blood vessels.

Answer: A. Bedaquiline

Explanation: Bedaquiline was the first in class drug to inhibit mycobacterial ATP synthase and is approved for the treatment of multi-drug resistant tuberculosis.

Answer: D. Regular

Explanation: Regular insulin is the only type that is suitable for intravenous administration, providing rapid onset of action.

Answer: A. Gs

Explanation: The Gs protein stimulates adenylate cyclase, thereby increasing cyclic AMP levels within the cell, which is essential for many signal transduction pathways.