Pharmacy & Medication Management Flashcards

A patient on warfarin therapy presents with a sudden INR of 8.2 but no active bleeding. Which of the following is the MOST appropriate immediate management?

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

For a supratherapeutic INR (>8) without active bleeding, current guidelines recommend holding warfarin and giving low-dose oral vitamin K (2–5 mg). This achieves INR reversal within 24 hours without the risk of over-correction or thromboembolism. IV vitamin K at high doses is reserved for serious/life-threatening bleeding. Protamine sulfate reverses heparin, not warfarin.

A pharmacist receives a prescription for methotrexate 15 mg to be taken DAILY for rheumatoid arthritis. The prescriber insists the daily dose is intentional. What is the pharmacist's BEST course of action?

Answer: Refuse to dispense and report the prescription as a potential critical error, since methotrexate for RA is dosed weekly

Methotrexate for rheumatoid arthritis is dosed WEEKLY, not daily. Daily dosing is a well-documented, life-threatening prescribing error associated with severe toxicity and death. Even if a prescriber insists on daily dosing, the pharmacist has a professional and ethical obligation to refuse dispensing and escalate the error through appropriate reporting channels. The pharmacist's duty overrides prescriber insistence when patient safety is at risk.

Which pharmacokinetic parameter is MOST directly used to determine the maintenance dose of a drug when the target plasma concentration and clearance are known?

Answer: Steady-state infusion rate (R₀ = Css × CL)

Maintenance dose (or infusion rate) is calculated as R₀ = Css × CL, where Css is the desired steady-state plasma concentration and CL is drug clearance. Volume of distribution governs loading dose (LD = Css × Vd), and half-life determines time to steady state. Bioavailability adjusts oral dosing but is not the primary determinant of the maintenance dose rate itself.

A patient with severe renal impairment (CrCl < 15 mL/min) is prescribed enoxaparin for treatment of deep vein thrombosis. Which of the following adjustments is MOST appropriate?

Answer: Switch to unfractionated heparin (UFH) monitored by aPTT

Low-molecular-weight heparins (LMWHs) such as enoxaparin are primarily renally eliminated. In severe renal impairment (CrCl <30 mL/min, especially <15 mL/min), enoxaparin accumulates unpredictably, significantly raising bleeding risk. The safest approach is switching to unfractionated heparin, which is not renally cleared and can be precisely monitored via aPTT and reversed with protamine. Fondaparinux is actually contraindicated in severe renal impairment as it is 100% renally excreted.

A patient stable on clozapine for 3 years is started on ciprofloxacin for a urinary tract infection. Two weeks later he presents with excessive sedation and drooling. What is the MOST likely explanation?

Answer: Ciprofloxacin inhibits CYP1A2, increasing clozapine plasma levels to toxic concentrations

Clozapine is primarily metabolized by CYP1A2. Ciprofloxacin is a significant CYP1A2 inhibitor; co-administration reduces clozapine clearance, leading to substantially elevated plasma clozapine levels. Symptoms of clozapine toxicity include sedation, drooling (hypersalivation), confusion, and seizures. Clinicians must either avoid fluoroquinolones in clozapine patients or significantly reduce the clozapine dose with close monitoring during antibiotic treatment.

Under UAE/DHA pharmaceutical regulations, which of the following controlled substances requires a SPECIAL (red) prescription and is subject to the STRICTEST dispensing controls, including a maximum 7-day supply per prescription?

Answer: Morphine

Under UAE Federal Law No. 14 of 1995 and DHA regulations, Schedule 1 controlled narcotics such as morphine require a specially controlled (red) prescription issued by an authorized physician, with strict quantity limits (typically a 7-day supply maximum) and mandatory register recording at the dispensing pharmacy. Tramadol and pregabalin are Schedule 2/controlled but have different prescription requirements. Midazolam requires controlled handling but falls under a separate psychotropic schedule.