Answer: C. Caspofungin

Explanation: Caspofungin is an antifungal agent that inhibits β-glucan synthesis; it does not inhibit RNA polymerase, unlike rifampicin and doxorubicin which have inhibitory effects on nucleic acid synthesis.

Answer: D. Amlodipine

Explanation: Amlodipine has minimal interaction with digoxin, whereas cholestyramine, thiazide diuretics, and quinidine can alter digoxin levels.

Answer: D. All of the above

Explanation: Certain betacarbolines, specific cannabinoids, and yohimbine have been shown to reduce basal receptor activity, thus acting as inverse agonists.

Answer: C. It increases nitric oxide formation

Explanation: Nebivolol is a beta-1 blocker with additional nitric oxide-mediated vasodilatory properties, enhancing its cardiovascular benefits.

Answer: D. A & B both

Explanation: Sulphonamides act by inhibiting the synthesis of folic acid in bacteria, interfering with both absorption of para-aminobenzoic acid and the subsequent folate production.

Answer: A. Ceftriaxone

Explanation: Ceftriaxone can displace bilirubin from albumin, increasing free bilirubin levels and the risk of kernicterus in neonates.

Answer: C. Cisapride

Explanation: Cisapride is a prokinetic agent that increases gastrointestinal motility by enhancing acetylcholine release in the gut.

Answer: A. Decrease in response of drug

Explanation: Tachyphylaxis refers to a rapid decrease in the response to a drug after its initial administration, necessitating increased doses for the same effect.

Answer: C. Paromomycin

Explanation: Paromomycin is used to treat leishmaniasis because of its activity against the protozoan parasite, offering an effective alternative in regions with high resistance.

Answer: A. Nucleic acid

Explanation: Nitrogen mustards are alkylating agents that react with nucleic acids, crosslinking DNA strands and thereby inhibiting replication and transcription in cancer cells.

Answer: D. PDE4

Explanation: Roflumilast is a selective phosphodiesterase-4 inhibitor that reduces inflammation by increasing intracellular cAMP levels, making it useful in treating chronic obstructive pulmonary disease.

Answer: D. P, R, and S

Explanation: Drug specificity is influenced by the dose and receptor affinity, as well as the delivery system; the route of administration indirectly affects these factors.

Answer: D. Causes respiratory acidosis

Explanation: Morphine typically causes respiratory depression, not respiratory acidosis; the other statements accurately describe its effects.

Answer: B. Sodium cromoglycate

Explanation: Sodium cromoglycate is permitted by the International Olympic Committee, whereas drugs like salbutamol, spironolactone, and erythropoietin are banned for their performance-enhancing or masking effects.

Answer: A. PGE1 agonist

Explanation: PGE1 agonists are used to protect the gastric mucosa by enhancing mucus secretion, increasing blood flow, and stimulating bicarbonate production, thereby reducing ulcer risk.

Answer: A. Methotrexate

Explanation: Urine alkalinization is used during high-dose methotrexate therapy to prevent drug crystallization in the renal tubules, thereby reducing the risk of nephrotoxicity.

Answer: D. Brahmi

Explanation: Brahmi is traditionally used as a nervine tonic in Ayurvedic medicine to enhance cognitive function and reduce stress.

Answer: A. Ketoconazole

Explanation: Ketoconazole inhibits fungal cytochrome P450 enzymes involved in ergosterol synthesis, which is essential for maintaining fungal cell membrane integrity.

Answer: D. Vascular selectivity

Explanation: Non-dihydropyridine calcium antagonists tend to have greater effects on the heart, whereas dihydropyridines like amlodipine are more selective for vascular smooth muscle, reducing blood pressure with fewer cardiac effects.

Answer: A. Nicorandil

Explanation: Nicorandil acts as a potassium channel opener and nitrate, which together lead to vasodilation and are used in the treatment of angina pectoris.