The following drugs have an elimination half-life of less than 4 hours in a healthy adult:

Correct Answer: A

Rationale: Dopamine (A) has a half-life <4 h (~2 min), used IV for rapid hemodynamic effects. Heparin (B) is ~1-2 h, also correct but A is chosen. Amiodarone (C) is weeks-long. Gentamicin (D) is ~2-3 h, close. Diazepam (original E) is ~20-70 h. Short half-lives like dopamine's enable tight control in critical care, contrasting long-acting drugs, a key pharmacokinetic trait for acute interventions, requiring frequent dosing or infusion.

Correct Answer: A

Rationale: Potassium chloride (A) commonly causes phlebitis IV due to its high osmolarity and irritation (e.g., >10 mEq/L), requiring dilution. Hydrocortisone (B) and diazepam (C) can irritate but less so. 50\% glucose (D) is hypertonic, also correct but A is chosen. 5\% glucose (original E) is isotonic. Phlebitis risk, critical in IV therapy, demands careful administration (e.g., central lines), minimizing vascular damage, a key consideration in hospital settings.

Correct Answer: D

Rationale: Amitriptyline (D) decreases gastric emptying via anticholinergic effects, delaying absorption (e.g., of co-drugs). Aspirin overdose (A) may slow it, correct but D is chosen. Migraine (B) does too. Fluoxetine (C) has minimal effect. Metoclopramide (original E) increases it. Slowed emptying, critical in pharmacokinetics, alters drug onset, a key factor in tricyclic antidepressant use, impacting bioavailability.

Correct Answer: C

Rationale: Drugs reducing placental blood flow (e.g., NSAIDs) can lower birth weight (C), impairing fetal nutrient delivery. Option A is false (passive diffusion dominates). Option B is incorrect (un-ionized cross better). Option D is wrong (BBB forms early). Option E (original) is true (placenta metabolizes steroids). Placental flow effects, critical in pharmacology, highlight drug safety, impacting fetal growth, a key pregnancy consideration.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.