Vitamin K (Coagulation Factor Synthesis) Pregnancy: C

Phytomenadione (Vitamin K1)

Brand names: Konakion MM Paediatric, Konakion MM

Adult dose

Dose: 1–5 mg IV/oral (warfarin reversal); 10 mg IV (serious bleed reversal)

Route: oral, IV slow injection

Frequency: once (repeat if INR remains elevated)

Max: 10 mg per dose

Oral route preferred unless urgent reversal needed; IM route AVOID (variable absorption, haematoma risk); IV via diluted slow infusion

Paediatric dose

Route: oral, IM (newborn VKDB prophylaxis); IV slow if reversal needed

Frequency: Single IM dose at birth (term); oral schedule × 3 doses (alternative)

Max: 10 mg per dose (older children/IV reversal)

Concentration: 2 mg/0.2 mL (paediatric) or 10 mg/mL mg/ml

Age bands

0–1m: Term neonate: 1 mg IM at birth, OR 2 mg oral × 3 doses (breastfed). Preterm <36 wk: 0.4 mg/kg IM (max 1 mg).

BNFc neonatal vitamin K (VKDB prophylaxis) is FIXED-DOSE not weight-based: term neonate ≥36 weeks 1 mg IM single dose at birth (preferred), OR 2 mg orally at birth + 2 mg orally days 4–7 + 2 mg orally at 1 month (breastfed). Preterm <36 weeks: 0.4 mg/kg IM single dose (max 1 mg). Anticoagulant reversal in older children (BNFc): 30 micrograms/kg slow IV (warfarin minor bleed) up to 5 mg slow IV (major bleed). All slow IV — anaphylactoid risk.

Dose adjustments

Renal

No dose adjustment required

Hepatic

May have reduced effect in severe hepatic disease (impaired factor synthesis regardless of vitamin K)

Clinical pearls

IV infusion over 15–30 min — rapid IV injection causes anaphylactoid reactions
INR reversal: 4-factor PCC for immediate reversal; phytomenadione for sustained correction
After large doses (10 mg+), warfarin resistance for up to 7 days — consider switching to LMWH if ongoing anticoagulation needed

Contraindications

None absolute; caution with IV anaphylaxis risk

Side effects

Anaphylactoid reactions (IV — especially rapid injection)
Pain at injection site
Erythema
Haematoma (IM route)

Interactions

Warfarin (antagonises anticoagulant effect)
Orlistat (reduces vitamin K absorption)

Monitoring

INR (2–4h after IV, 24h after oral)
Signs of bleeding resolution

Reference: BNFc; BNF 86; BCSH Guidelines on anticoagulation reversal. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways