Clinical Pharmacy and Therapeutics Flashcards

A patient presents with acute severe asthma (PEFR 30% predicted). What is the sequence of emergency pharmacological management?

Answer: High-dose inhaled SABA (salbutamol nebulized) + ipratropium + IV/oral corticosteroids + IV magnesium sulfate if severe

Acute severe asthma: (1) repeated nebulized salbutamol + ipratropium (maximizing bronchodilation); (2) early systemic corticosteroids (prednisolone 40–50 mg PO or IV hydrocortisone) to reduce airway inflammation; (3) IV magnesium sulfate (bronchodilator, relaxes smooth muscle) for PEFR <50% despite initial treatment.

A pharmacist counsels a patient on the use of methotrexate (MTX) plus folic acid for rheumatoid arthritis. Why is folic acid prescribed?

Answer: Folic acid reduces MTX-related mucositis, GI side effects, and myelosuppression without significantly reducing anti-inflammatory efficacy

MTX inhibits dihydrofolate reductase, depleting folate. Supplemental folic acid (5 mg once weekly, on a different day from MTX) replenishes folate, reducing adverse effects (mucositis, nausea, abnormal LFTs, myelosuppression) without significantly impairing MTX's anti-inflammatory effects in RA.

A patient on warfarin starts taking amiodarone. What change in INR should be expected?

Answer: INR will increase significantly — amiodarone inhibits CYP2C9 and CYP3A4 reducing warfarin clearance

Amiodarone is a potent inhibitor of CYP2C9 (and CYP3A4, P-glycoprotein) that dramatically reduces warfarin clearance, increasing INR and bleeding risk. The interaction is delayed (may take weeks to manifest fully) and persists for months after amiodarone is stopped due to its very long half-life (40–55 days).

Which therapeutic approach is used for acetaminophen (paracetamol) overdose?

Answer: N-acetylcysteine (NAC) IV or oral — replenishes glutathione to detoxify NAPQI

Paracetamol overdose generates NAPQI (toxic metabolite) that depletes hepatic glutathione, causing hepatocellular necrosis. NAC replenishes glutathione (directly and as precursor), neutralizes NAPQI, and is most effective within 8–10 hours but beneficial up to 24 hours. Activated charcoal can be given within 1 hour of ingestion.

A pharmacist is asked about antibiotic prophylaxis for a patient undergoing elective total knee replacement. What is the recommended regimen?

Answer: IV cefazolin 2 g within 60 minutes of incision; additional doses intraoperatively if surgery >4 hours — stop within 24 hours

Surgical antimicrobial prophylaxis for orthopedic procedures: IV cefazolin (first-generation cephalosporin) given within 60 minutes of incision (30 min for vancomycin/fluoroquinolone). Re-dose if surgery >4 hours or blood loss >1.5 L. Duration should not exceed 24 hours post-incision — extending duration increases resistance and C. diff risk.

A patient presents with symptoms of serotonin syndrome after starting linezolid while taking an SSRI. Which symptom triad is characteristic?

Answer: Agitation, hyperthermia, and neuromuscular abnormalities (tremor, clonus, hyperreflexia)

Serotonin syndrome presents with the Hunter triad: (1) neuromuscular features (clonus, hyperreflexia, tremor), (2) altered mental status (agitation, anxiety), (3) autonomic instability (hyperthermia, diaphoresis, tachycardia). Linezolid is a weak MAO inhibitor; combined with SSRIs it causes serotonin excess.