Advanced Pharmacology Flashcards

A 70-year-old patient on warfarin for atrial fibrillation is admitted for pneumonia. The patient develops QTc prolongation (QTc 520 ms) on the cardiac monitor. Which antibiotic should the CNS recognize as most likely contributing to QT prolongation?

Answer: Azithromycin

Azithromycin (and fluoroquinolones) are well-documented QT-prolonging antibiotics — macrolides inhibit cardiac hERG potassium channels, prolonging ventricular repolarization.

A patient with severe sepsis requires vasopressor support. Norepinephrine has been initiated. The intensivist is considering adding vasopressin. What is the primary pharmacological rationale for vasopressin use in septic shock?

Answer: Vasopressin acts on V1 receptors independently of adrenergic receptors, compensating for relative vasopressin deficiency in septic shock

Vasopressin acts on V1 (vascular) receptors to cause vasoconstriction independently of adrenergic signaling, compensating for the relative vasopressin deficiency seen in prolonged septic shock.

A 65-year-old patient with CKD stage 4 (GFR 22 mL/min) requires pain management after total knee replacement. Which opioid selection and dosing consideration is most appropriate?

Answer: Hydromorphone at reduced doses with extended dosing intervals is safer than morphine in significant renal impairment

Hydromorphone is preferred over morphine in renal impairment; morphine's active metabolite (M6G) accumulates in renal failure causing CNS/respiratory depression.

A patient on chronic prednisone 20 mg daily for rheumatoid arthritis requires emergency appendectomy. What is the critical perioperative pharmacological concern?

Answer: Hypothalamic-pituitary-adrenal (HPA) axis suppression requiring stress-dose steroids

Chronic glucocorticoid use suppresses the HPA axis; surgical stress requires cortisol surge that suppressed adrenal glands cannot produce — stress-dose steroids prevent adrenal crisis.

A CNS reviewing a patient's medication list notes the patient takes simvastatin 80 mg and has been newly prescribed clarithromycin for H. pylori. What is the critical drug interaction concern?

Answer: Clarithromycin inhibits CYP3A4, dramatically increasing simvastatin levels and risk of rhabdomyolysis

Clarithromycin is a potent CYP3A4 inhibitor; simvastatin is a CYP3A4 substrate — co-administration dramatically increases simvastatin AUC (up to 10-fold), causing severe rhabdomyolysis risk.

A patient in the ICU requires sedation management. The CNS is implementing the ABCDEF bundle. Which sedation agent is most appropriate per current evidence for mechanically ventilated patients, and what is the preferred sedation target?

Answer: Dexmedetomidine or propofol targeting light sedation (RASS -1 to 0) per PADIS guidelines

PADIS guidelines (2018) recommend light sedation targets (RASS -1 to 0) with non-benzodiazepine agents (dexmedetomidine, propofol); benzodiazepines increase delirium risk.