The question
Work it with the BNF open before you show the answer. At exam pace this item has 6 minutes.
A 73-year-old man is brought to the emergency department after vomiting fresh blood twice this evening, having passed black tarry stools since this morning. He takes warfarin for atrial fibrillation, and 5 days ago his dentist started an antibiotic for a dental abscess. He is in the resuscitation area: the major haemorrhage protocol has been activated, the transfusion laboratory — which confirms full stocks — has issued red cells, and the first unit is running. Phytomenadione 5 mg has been given by slow intravenous injection and tonight's warfarin is withheld.
PMH: atrial fibrillation; hypertension; dental abscess (5 days ago).
DH: warfarin sodium PO daily (target INR 2.5, usual maintenance 4 mg); metronidazole 400 mg PO three times daily (8-hrly), day 5 of 7 (dental abscess); ramipril 5 mg PO daily; atorvastatin 20 mg PO nightly. No known drug allergies.
SH: retired plumber; lives with his wife; drinks 4 units of alcohol a week; non-smoker.
On examination: Temperature 36.4°C, HR 118/min and irregularly irregular, BP 92/58 mmHg, RR 22/min, O2 sat 96% breathing air. Weight 80 kg. Pale, cool peripheries with a prolonged capillary refill; alert and answering questions. Epigastric tenderness; melaena on rectal examination. Two large-bore cannulae are sited; the first unit of red cells is running through one of them.
Investigations: Hb 72 g/L (130–180) Platelets 256 ×10⁹/L (150–400) Na 138 mmol/L (135–145), K 4.4 mmol/L (3.5–5.3) Urea 14.2 mmol/L (2.5–7.8), creatinine 102 µmol/L (60–120) INR 6.8 (target 2.5) Cross-match: 2 units of red cells issued, further units available
Answer and marking
dried prothrombin complex (four-factor prothrombin complex concentrate, Beriplex® P/N) · 2400 units (30 units/kg) · intravenous (IV) infusion · once only
Marks5 for the drug choice, 5 for the written prescription (dose, route, frequency).
Also crediteddried prothrombin complex; prothrombin complex concentrate; prothrombin complex; PCC; Beriplex; Octaplex
Drug choiceWarfarin reversal in major bleeding is a two-drug algorithm, and the marks here are for the drug that works tonight. The BNF's haemorrhage guidance reads: 'Major bleeding—stop warfarin sodium; give phytomenadione (vitamin K1) by slow intravenous injection; give prothrombin complex (factors II, VII, IX, and X); if prothrombin complex unavailable, fresh frozen plasma can be given but is less effective; recombinant factor VIIa is not recommended for emergency anticoagulation reversal' (BNF, oral anticoagulants treatment summary, read 22 August 2026). The phytomenadione has been given — it switches factor synthesis back on, but synthesis takes hours this haematemesis will not wait for. Dried prothrombin complex IS the missing factors, in a vial: II, VII, IX and X, reconstituted and infused in minutes. Fresh frozen plasma earns partial credit only, because the BNF's condition for it — prothrombin complex unavailable — is printed false: the laboratory is fully stocked, and plasma is slower (thawing), bulkier (a volume load in a shocked man) and weaker (dilute factors). Writing phytomenadione again earns a single mark for knowing the algorithm's other arm: it is already running and the question asks for the ONE additional drug. The zeros are the wrong-patient reversal shelf: idarucizumab reverses dabigatran, andexanet alfa reverses apixaban and rivaroxaban, protamine reverses heparin, and recombinant factor VIIa is the product the BNF's algorithm itself rules out by name.
Dose, route and frequencyThe BNF dose is 25–50 units/kg by intravenous infusion (prothrombin complex monograph, read 22 August 2026) — for this man's printed 80 kg, 2000–4000 units; the model answer takes 30 units/kg = 2400 units. Write 'units': the Beriplex SmPC's own INR-banded table (50 IU/kg above an INR of 6.0, capped at 5000 IU in patients over 100 kg) sits inside the BNF band at this weight. The characteristic dose error is writing a VIAL as a dose: prothrombin complex comes in 500-unit and 1000-unit vials, and 500 units is about 6 units/kg for this man — a token. Under-dosing at 10–24 units/kg loses 4 of the 5 prescription marks; anything above 50 units/kg over-doses a prothrombotic product in a man with atrial fibrillation and scores nothing for the prescription half.
ExplanationAlso part of the plan, though not marked in the boxes: urgent endoscopy once resuscitated, a recheck of the INR after the infusion, stopping the metronidazole interaction review (BNF: 'Metronidazole increases the anticoagulant effect of Warfarin', severity severe), and a documented plan for if and when anticoagulation restarts.
dried prothrombin complex (prothrombin complex concentrate / PCC / Beriplex® P/N / Octaplex®) — 25–50 units/kg (2000–4000 units for 80 kg), intravenous infusion, once only. Full marks. 10–24 units/kg (800–1999 units): 5 + 1. Token doses and doses above 50 units/kg: 5 + 0. fresh frozen plasma (FFP / Octaplas®) — 2 + 0. phytomenadione (vitamin K) — 1 + 0. tranexamic acid — 1 + 0. recombinant factor VIIa, idarucizumab, andexanet alfa, protamine, or any 'PCC or FFP' hedge — 0/10. (BNF oral anticoagulants treatment summary, prothrombin complex and phytomenadione monographs, and metronidazole interactions page, all read 22 August 2026; Beriplex P/N SmPC read the same day.)
How this item is marked
Every answer is matched to a marking tier. The first rows below are from this item's real scheme (65 tiers in total).
| Medicine | Dose and route | Marks | Marking note |
|---|---|---|---|
| dried prothrombin complex | 25-50 units/kg · intravenous (IV) | 10 / 10 | optimal, written per kilogram. BNF, prothrombin complex monograph: 'Major bleeding in patients on warfarin [following phytomenadione] … By intravenous infusion,… |
| dried prothrombin complex | 2000-4000 units · intravenous (IV) | 10 / 10 | the same dose resolved against his printed 80 kg: 25 × 80 = 2000 units, 50 × 80 = 4000 units. Credited identically. |
| dried prothrombin complex | 10-24 units/kg · intravenous (IV) | 6 / 10 | below the BNF's 25 units/kg floor — a partial factor replacement that under-corrects an INR of 6.8. Deduct 4 rather than zero: the drug and route are right and … |
| dried prothrombin complex | 800-1999 units · intravenous (IV) | 6 / 10 | the same underdose written in absolute units (10–24.9 units/kg at 80 kg). Deduct 4. |
| dried prothrombin complex | 1-9 units/kg · intravenous (IV) | 5 / 10 | a token dose — a fraction of any effective regimen. Right drug, failed prescription half. |
| dried prothrombin complex | 1-799 units · intravenous (IV) | 5 / 10 | the remembered vial size (500 or 1000-unit vials exist) written as the dose: under 10 units/kg for this 80 kg man. Zero for the prescription half. |
| dried prothrombin complex | 51-150 units/kg · intravenous (IV) | 5 / 10 | above the 50 units/kg ceiling of a prothrombotic product given to a man with atrial fibrillation. Zero for the prescription half. |
| dried prothrombin complex | 4001-12000 units · intravenous (IV) | 5 / 10 | the same overdose in absolute units. Zero for the prescription half. |
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How to approach a prescribing item
The repeatable method from the Prescribing section guide.
- Name the indicationSay in one phrase what the drug is for. If you cannot, you are not ready to choose one.
- Choose the class, then the drugThe BNF treatment summary gives the class and first-line agent; the case's modifiers pick the drug within it.
- Find the dose under the right indicationMonographs list several indications with different doses. Read the heading, not the first number.
- Apply the patientWeight-based? Renal impairment? Age band? Pregnancy? Each can change the dose or the drug.
- Write it as the chart needs itDose in a unit, route from the accepted list, frequency in words the chart uses, once-only or regular as instructed.
Before you submit
- Is the drug I chose the first-line agent for this indication, in this patient?
- Is the dose taken from the right indication in the monograph?
- Have I written a dose in a unit, not a volume?
- Does the route exist for this drug and this form?
- Is there a frequency, and is it in the chart's words?
- Have I checked renal function, allergy and the interaction the case mentions?
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