The following drugs undergo significant enterohepatic circulation:

Correct Answer: A

Rationale: Oestrogens undergo enterohepatic circulation as they are conjugated in the liver, excreted in bile, and reabsorbed in the intestine, prolonging their action.

Correct Answer: C

Rationale: The relationship of the blood concentration attained with initial dosing and the dose of drug given is best described by the concept of steady state. Steady state refers to the point at which the rate of drug input (dose) equals the rate of drug elimination, resulting in consistent drug levels in the blood. Achieving steady state typically requires several half-lives of the drug, during which the drug concentration gradually increases with each dose until it stabilizes. The dose of the drug given will influence how quickly steady state is reached and at what concentration the drug will be maintained in the body. Factors such as bioavailability, half-life, volume of distribution, and clearance play important roles in determining the dosage needed to reach and maintain steady state drug levels in the body.

Correct Answer: D

Rationale: Enteric-coated medications are designed to resist dissolution in the stomach and release the active ingredient in the intestines. Chewing or crushing the tablet can compromise the coating, leading to premature drug release and potential irritation of the stomach lining. Therefore, the nurse should instruct the patient to swallow the tablet whole without chewing. Taking the tablet with orange juice or avoiding other medications is not necessary, and crushing the tablet is contraindicated. Proper administration ensures the medication's effectiveness and minimizes the risk of adverse effects.

Correct Answer: C

Rationale: An autologous blood product is the safest option because it involves the patient donating their own blood before surgery, eliminating the risk of transfusion reactions or infections from donor blood. Allogeneic products come from other donors and carry a small risk of infection or incompatibility. Directed donations are from known donors but still carry some risks. Cross-matching ensures compatibility but does not eliminate infection risks. Therefore, autologous donation is the safest choice.

Correct Answer: C

Rationale: Morphine is a potent opioid analgesic that is commonly used for pain management, but it is not typically used to treat diarrhea and dysentery. Instead, medications such as loperamide or diphenoxylate/atropine are more commonly employed for managing diarrhea. Morphine can actually cause constipation as a side effect due to its action on opioid receptors in the gut. Therefore, the statement that morphine is used to treat diarrhea and dysentery is false.

Correct Answer: C

Rationale: Warfarin is highly bioavailable (near 100%), so 90% is close and true. It doesn't inactivate vitamin K but inhibits vitamin K epoxide reductase, reducing clotting factor synthesis, making that false. It can paradoxically cause venous thrombosis (e.g., skin necrosis) early in therapy due to protein C depletion, a true statement. Initial loading is typically 5-10 mg, not 0.5 mg, so that's false. Metronidazole increases its effect via metabolism inhibition, not bactericidal action. The thrombosis risk is a rare but serious side effect, highlighting the need for bridging with heparin during initiation.

Correct Answer: A

Rationale: The limbic system (e.g., amygdala) drives anxiety-emotional response-while the reticular activating system (RAS) regulates sleep-wake, impacting insomnia, per neuroanatomy. Frontal lobes plan, not directly control these. Thalamus relays, not initiates. Hypothalamus affects sleep but less anxiety. Limbic-RAS pairing fits, answering precisely.

Correct Answer: D

Rationale: Lamotrigine, a broad-spectrum antiepileptic, treats absence seizures by stabilizing sodium channels and inhibiting glutamate release, though less specific than ethosuximide. Topiramate and levetiracetam manage multiple seizure types but aren't first-line for absence. Tiagabine, a GABA reuptake inhibitor, may worsen absence seizures. Zonisamide has broad efficacy but less absence focus. While ethosuximide is gold standard, lamotrigine's utility in absence, especially in mixed epilepsies, and clinical evidence make it the most useful here among options.

Correct Answer: A

Rationale: Cyclophosphamide in ALL risks hemorrhagic cystitis from acrolein, a toxic metabolite. Mesna binds acrolein, preventing bladder damage. Methylene blue , N-acetylcysteine , Ibuprofen , and Succimer (E) don't address this. Mesna's specificity ensures safe chemotherapy, critical in this young patient.