Answer: D. Peptic ulcer

Explanation: Aspirin is contraindicated in peptic ulcer disease because it can cause gastrointestinal irritation and bleeding, despite its effectiveness in reducing inflammation and pain and its use in preventing heart attacks.

Answer: C. Edoxaban

Explanation: Edoxaban, an oral anticoagulant, was approved by the USFDA in 2015 for the prevention of stroke in patients with non-valvular atrial fibrillation, offering an alternative to traditional therapies.

Answer: B. Limited expression of glucuronyl transferase

Explanation: Gray baby syndrome occurs because neonates have limited expression of glucuronyl transferase, the enzyme needed to metabolize chloramphenicol, leading to toxic accumulation and adverse effects.

Answer: A. Isonicotinic acid hydrazide

Explanation: Isoniazid is chemically known as isonicotinic acid hydrazide. It is used primarily as an antitubercular agent and requires activation by bacterial enzymes to exert its therapeutic effect.

Answer: A. Bosentan

Explanation: Bosentan is an endothelin receptor antagonist used in pulmonary hypertension. It works by dilating blood vessels, reducing pulmonary arterial pressure, and improving symptoms in affected patients.

Answer: D. Antiadrenergic actions

Explanation: Cyproheptadine exhibits antimuscarinic, antihistaminic, and antiserotonergic activities. It does not significantly block adrenergic receptors, which distinguishes it from other drugs with antiadrenergic effects.

Answer: B. TNF-α antagonist

Explanation: Infliximab is a monoclonal antibody that neutralizes tumor necrosis factor-alpha (TNF-α), a key pro-inflammatory cytokine, thereby reducing inflammation in conditions such as rheumatoid arthritis and Crohn's disease.

Answer: C. Folic acid

Explanation: Folic acid is used to prevent neural tube defects, whereas drugs like phenytoin, valproic acid, and carbamazepine are known to increase the risk of these congenital abnormalities if taken during pregnancy.

Answer: B. Because cholesterol synthesis increases at night

Explanation: Statin drugs are administered at night because the body’s cholesterol synthesis is higher during the night. This timing enhances the efficacy of the drug in lowering cholesterol levels.

Answer: A. Antimotility

Explanation: Domperidone is a prokinetic (promotility) agent. Correct answer is B.

Answer: A. Nephrotoxicity

Explanation: Amphotericin is well known for its nephrotoxicity. Its use can cause kidney damage by affecting renal tubular function, which limits its dosage and requires careful patient monitoring during treatment.

Answer: C. Liver, kidney, and brain

Explanation: Highly perfused organs such as the liver, kidney, and brain receive drugs rapidly following intravenous administration due to their extensive blood supply and high metabolic activity.

Answer: C. Constipation

Explanation: A kappa-selective agonist typically causes constipation by reducing gastrointestinal motility. This side effect results from kappa receptor activation, which can inhibit smooth muscle contraction in the gut.

Answer: C. Repaglinide

Explanation: Repaglinide is preferred for treating mild hypoglycemia in obese patients because it has a rapid onset and short duration of action, which helps control postprandial blood glucose levels without causing excessive hypoglycemia.

Answer: A. Pralidoxime + Atropine

Explanation: Pralidoxime combined with atropine is the treatment of choice for organophosphorus poisoning. Atropine counteracts muscarinic effects, while pralidoxime reactivates acetylcholinesterase inhibited by organophosphates.

Answer: C. Entacapone

Explanation: Entacapone is a COMT inhibitor used alongside L-dopa in Parkinson’s disease therapy. By inhibiting peripheral metabolism of L-dopa, it increases the amount of drug reaching the brain.

Answer: A. Pilocarpine

Explanation: Physostigmine is the standard antidote for atropine poisoning, not pilocarpine.

Answer: D. Naltrexone

Explanation: Pure narcotic antagonists like naltrexone block opioid receptors without intrinsic activity. They are used to reverse opioid overdose and manage opioid dependence by competitively inhibiting opioid effects.

Answer: A. Ventricular arrhythmia

Explanation: Co-administration of cisapride and fluconazole can lead to dangerous ventricular arrhythmias due to drug interactions that prolong the QT interval. This risk necessitates avoiding their simultaneous use.

Answer: A. One-compartment model

Explanation: The one-compartment model assumes that a drug distributes instantaneously and uniformly throughout the body. This simplification is useful for calculating pharmacokinetic parameters when distribution is rapid.