Answer: A. mu; kappa

Explanation: Euphoria is typically mediated by mu opioid receptors, while kappa receptor activation is associated with dysphoria. This explains the differing emotional responses elicited by drugs acting on these receptors.

Answer: C. Venlafaxin

Explanation: Venlafaxin is a serotonin-norepinephrine reuptake inhibitor (SNRI) that increases the levels of both 5HT and NE in the synaptic cleft, thereby alleviating symptoms of depression.

Answer: A. alteplase

Explanation: Tranexamic acid works by inhibiting fibrinolysis. It prevents the breakdown of blood clots, thus antagonizing the effect of thrombolytic agents like alteplase that promote clot dissolution.

Answer: B. 0.93

Explanation: In first-order kinetics, after four half-lives approximately 93% of the drug is eliminated from the body, reflecting the exponential decay of drug concentration over time.

Answer: D. None of the above

Explanation: Rifaximin is approved for hepatic encephalopathy.

Answer: D. Sweat glands

Explanation: Physostigmine and bethanechol affect muscarinic receptors in many tissues; however, sweat glands are innervated by sympathetic cholinergic fibers, making their response different from the others.

Answer: B. Misoprostol

Explanation: Misoprostol is the agent of choice for terminating a first-trimester pregnancy. It is a prostaglandin analogue that induces uterine contractions and cervical ripening to effect termination.

Answer: A. Zero-order kinetics

Explanation: Ethanol elimination follows zero-order kinetics at therapeutic and toxic levels, meaning a constant amount is eliminated per unit time regardless of its concentration in the blood.

Answer: A. Ca++ influx

Explanation: Chromolyn sodium stabilizes mast cells by inhibiting calcium influx, which prevents degranulation and the release of histamine and other mediators, thereby reducing allergic reactions.

Answer: B. Tetracycline

Explanation: Tetracycline acts on the 30S ribosomal subunit, not the 50S. Chloramphenicol, oxazolidinones, and clindamycin inhibit 50S function, affecting peptide bond formation.

Answer: B. Cyclosporine

Explanation: Cyclosporine is a potent immunosuppressant used in transplant medicine to prevent organ rejection by inhibiting T-cell activation.

Answer: A. Artemolane and Piperaquine

Explanation: Synriam™ is a fixed-dose combination of artemolane and piperaquine, approved for the treatment of Plasmodium falciparum malaria. This combination offers rapid parasite clearance and sustained efficacy.

Answer: A. DDP-I inhibitor

Explanation: Albiglutide is a GLP-1 receptor agonist, not a DPP-IV inhibitor.

Answer: A. Chi-square test

Explanation: The chi-square test is used to compare proportions (such as response rates) between two independent groups to determine if there is a statistically significant difference.

Answer: A. adrenergic

Explanation: Urinary retention with first-generation H1 antagonists is due to anticholinergic (muscarinic) effects, not adrenergic. The correct answer should be B (cholinergic).

Answer: A. Safety

Explanation: The therapeutic index is the ratio of the toxic dose to the therapeutic dose and is used to assess the safety margin of a drug. A higher index indicates a safer drug.

Answer: C. Type I topoisomerases

Explanation: Camptothecin specifically inhibits type I topoisomerases, enzymes that relieve DNA supercoiling during replication. Its inhibition leads to DNA damage and cell death in rapidly dividing cancer cells.

Answer: D. H1 antagonist

Explanation: Antiemetic regimens for chemotherapy typically target 5HT3, D2, and NK1 receptors. H1 antagonists are not primarily used for this purpose, making them the exception.

Answer: B. Hypotension

Explanation: Steroids cause osteoporosis (bone matrix loss). Correct answer is C.

Answer: D. Suxamethonium

Explanation: Suxamethonium (succinylcholine) has a very short pharmacokinetic half-life that closely parallels its pharmacodynamic action, leading to rapid onset and short duration of neuromuscular blockade.