Pharmacy & Medication Management Flashcards

A patient on warfarin therapy presents with an INR of 8.2 and has minor gum bleeding but no major hemorrhage. Which is the most appropriate immediate intervention according to evidence-based practice?

Answer: Hold warfarin, administer oral vitamin K 1–2.5 mg, and recheck INR in 24 hours

For supratherapeutic INR (>8) with minor or no bleeding, guidelines recommend holding warfarin and administering low-dose oral vitamin K (1–2.5 mg). IV vitamin K is reserved for life-threatening bleeds; FFP is used when rapid reversal is urgently needed. Continuing warfarin in any dose is inappropriate at this INR level.

A pharmacist dispenses methotrexate for rheumatoid arthritis. The patient asks why she takes it only once a week. Which pharmacokinetic and safety rationale BEST explains weekly dosing?

Answer: Weekly dosing allows intracellular polyglutamate accumulation while reducing systemic toxicity from daily dosing

Methotrexate is converted intracellularly to polyglutamate forms that are retained and exert prolonged pharmacological effect. Daily low-dose regimens cause unacceptable cumulative toxicity (particularly hepatotoxicity and myelosuppression); once-weekly dosing maintains efficacy through polyglutamate accumulation while allowing sufficient clearance between doses to limit toxicity.

A 68-year-old patient with CKD (eGFR 22 mL/min/1.73 m²) is prescribed metformin for type 2 diabetes. What is the DHA-aligned/evidence-based correct action?

Answer: Contraindicate metformin and recommend an alternative antidiabetic agent

Metformin is contraindicated when eGFR falls below 30 mL/min/1.73 m² due to the risk of life-threatening lactic acidosis from drug accumulation. An eGFR of 22 is well below this threshold. Dose reduction does not eliminate the risk at this level. The pharmacist must recommend an alternative agent (e.g., a DPP-4 inhibitor with renal dose adjustment, or insulin).

Which of the following drug interactions represents a pharmacodynamic (not pharmacokinetic) mechanism that requires the most urgent clinical intervention?

Answer: Concurrent use of linezolid and tramadol precipitating serotonin syndrome

Linezolid is a reversible MAO inhibitor, and tramadol promotes serotonin release and reuptake inhibition. Together they can trigger serotonin syndrome — a potentially life-threatening pharmacodynamic interaction requiring immediate drug discontinuation and supportive care. The other options are pharmacokinetic (enzyme inhibition/induction) interactions, which are clinically significant but generally less acutely dangerous than serotonin syndrome.

A hospital pharmacist reviews a chemotherapy order: cisplatin 100 mg/m² for a patient with a BSA of 1.8 m². The oncologist orders 180 mg in 250 mL NS over 1 hour. What is the MOST critical pharmacist intervention before dispensing?

Answer: Verify the BSA calculation and confirm hydration protocol — cisplatin requires pre- and post-hydration with at least 1–2 L NS to prevent nephrotoxicity

The dose calculation (100 mg/m² × 1.8 m² = 180 mg) is correct. However, the critical safety intervention is confirming the mandatory hydration protocol. Cisplatin is highly nephrotoxic, and adequate pre-hydration (1–2 L NS) and post-hydration, along with forced diuresis (mannitol or furosemide), are required to prevent acute kidney injury. Without this, dispensing would be inappropriate. NS is the correct diluent for cisplatin; D5W is incompatible.

A patient is prescribed carbamazepine for trigeminal neuralgia. Before dispensing the first prescription, which pharmacogenomic screening recommendation is MOST critical for a patient of Han Chinese or Thai descent?

Answer: HLA-B*15:02 genotyping to predict risk of Stevens-Johnson syndrome and toxic epidermal necrolysis

The HLA-B*15:02 allele is strongly associated with carbamazepine-induced Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), particularly in individuals of Han Chinese, Thai, and some other Asian ancestries. Major drug regulatory agencies (including FDA and EMA) recommend screening for HLA-B*15:02 before initiating carbamazepine in at-risk populations. HLA-B*57:01 is relevant to abacavir hypersensitivity, not carbamazepine.