How is Creatinine Clearance (CrCl) calculated for DOAC dosing in the UK?

In accordance with MHRA, BNF, and NICE guidelines, all direct oral anticoagulants (DOACs) must be dosed using Creatinine Clearance (CrCl) calculated via the Cockcroft-Gault equation using actual body weight, rather than automated laboratory eGFR.

When should Edoxaban be dose reduced to 30mg OD?

Edoxaban is reduced from 60mg OD to 30mg OD if the patient has CrCl 15–50 ml/min, body weight ≤ 60 kg, or is taking a concomitant strong P-gp inhibitor (e.g. Ciclosporin, Dronedarone, Erythromycin, or Ketoconazole).

When should Rivaroxaban be dose reduced in non-valvular AF?

For non-valvular atrial fibrillation, Rivaroxaban is reduced from 20mg OD to 15mg OD if the patient has moderate or severe renal impairment with CrCl 15–49 ml/min.

How often should renal function be monitored for patients on a DOAC?

According to the Specialist Pharmacy Service (SPS) and EHRA guidance, monitoring interval (in months) is estimated by CrCl divided by 10 (capped at 12 months for stable patients). A maximum interval of 4 months is recommended for patients aged ≥ 75 years or those with clinical frailty.

DOAC Dosing Calculator UK | Cockcroft-Gault & Dose Reduction

Q: What are the dose reduction criteria for Apixaban in non-valvular AF?

Apixaban is reduced from 5mg BD to 2.5mg BD if a patient meets at least two of the following three criteria: Age ≥ 80 years, Body weight ≤ 60 kg, or Serum Creatinine ≥ 133 µmol/L. Alternatively, reduction to 2.5mg BD is required if CrCl is 15–29 ml/min regardless of other criteria.

NHS Primary Care Clinical Reference

Clinical DOAC Dosing Guide, Renal Cut-Offs & Monitoring Protocols

Direct Oral Anticoagulants (DOACs) require regular assessment of renal function, body weight, age, and drug interactions to ensure safe, therapeutic anticoagulation. This clinical reference synthesises national guidance from the National Institute for Health and Care Excellence (NICE CKS), the British National Formulary (BNF), and the Specialist Pharmacy Service (SPS) for primary care prescribers and clinical pharmacists.

1. DOAC Dosing Matrix & Dose Reduction Criteria

DOAC (Brand)	Licensed Indications	Standard Target Dose	Dose Reduction Triggers	Contraindications (Renal)
Apixaban (Eliquis)	Non-valvular AF, DVT/PE treatment, VTE prophylaxis	5mg BD (10mg BD for acute 7-day DVT/PE load)	Reduce to 2.5mg BD if at least 2 of the following 3 criteria are met: Age ≥ 80 years Weight ≤ 60 kg Serum Creatinine ≥ 133 µmol/L OR if CrCl is 15–29 ml/min regardless of other criteria.	CrCl < 15 ml/min
Rivaroxaban (Xarelto)	Non-valvular AF, DVT/PE treatment, VTE prophylaxis	20mg OD (15mg BD for acute 21-day DVT/PE load; 10mg OD for post-op)	Reduce to 15mg OD if: CrCl is 15–49 ml/min (moderate to severe impairment) Note: Take with food to ensure optimal oral bioavailability.	CrCl < 15 ml/min
Edoxaban (Lixiana)	Non-valvular AF, DVT/PE treatment (after ≥5 days LMWH lead-in)	60mg OD	Reduce to 30mg OD if any 1 of the following applies: CrCl is 15–50 ml/min Body weight ≤ 60 kg Concomitant strong P-glycoprotein (P-gp) inhibitor (e.g. Ciclosporin, Dronedarone, Erythromycin, Ketoconazole)	CrCl < 15 ml/min
Dabigatran (Pradaxa)	Non-valvular AF, DVT/PE treatment (after ≥5 days LMWH lead-in), VTE prophylaxis	150mg BD (220mg OD for post-op hip/knee)	Reduce to 110mg BD if: Age ≥ 80 years (mandatory reduction) Concomitant Verapamil (mandatory reduction) Age 75–79 years with moderate renal impairment (CrCl 30–50 ml/min) or high bleeding risk	CrCl < 30 ml/min

2. Cockcroft-Gault Equation

MHRA Drug Safety Updates and the BNF emphasise that automated laboratory eGFR must not be used for DOAC dose adjustments. Automated eGFR is normalised to a standard body surface area (1.73 m²), which frequently overestimates renal clearance in elderly or low-weight patients, risking severe DOAC accumulation and major haemorrhage.

CrCl (ml/min) = [(140 − Age) × Weight (kg) × Constant] ÷ Serum Creatinine (µmol/L)

Constant = 1.23 for Males | 1.04 for Females

Weight Guidelines: Use actual body weight in primary care routine practice. In extreme obesity (weight > 120 kg or BMI > 40 kg/m²), Cockcroft-Gault may overestimate CrCl; consider using adjusted body weight or consult local haematology policy.

3. SPS & NICE Monitoring Protocols

According to the Specialist Pharmacy Service (SPS) and the European Heart Rhythm Association (EHRA), ongoing renal monitoring frequency should reflect the patient's baseline renal reserve:

CrCl ÷ 10

Standard Rule of Thumb Divide estimated CrCl by 10 to determine the re-test interval in months (e.g. CrCl 60 ml/min → every 6 months), up to a maximum of 12 months for stable patients.

≤ 4 Mo

Age ≥ 75 Years or Frailty Cap Apply a hard maximum monitoring interval of 4 months for patients aged 75 and above or those presenting with clinical frailty.

≤ 3 Mo

Impaired Renal Reserve (CrCl 15–30 ml/min) Review renal function, FBC, and bleed risk at least every 3 months.

4. Frequently Asked Questions (Primary Care Guidance)

Why must Cockcroft-Gault CrCl be used instead of eGFR? ▾

All pivotal DOAC clinical trials (ARISTOTLE, ROCKET-AF, ENGAGE-AF, RE-LY) determined renal eligibility and dose reduction criteria using the Cockcroft-Gault formula. Laboratory eGFR normalises for body surface area (1.73 m²), which frequently masks significant renal decline in patients who are elderly, have low muscle mass, or have body weight under 60 kg. Using eGFR can lead to dangerous over-dosing.

What are the exact dose reduction criteria for Apixaban in AF? ▾

For non-valvular atrial fibrillation, Apixaban is reduced from 5mg BD to 2.5mg BD if the patient meets at least two of these three criteria: Age ≥ 80 years, Body weight ≤ 60 kg, or Serum Creatinine ≥ 133 µmol/L. In addition, if CrCl is between 15 and 29 ml/min, 2.5mg BD is required regardless of age, weight, or creatinine.

How should Edoxaban be dosed with interacting medications? ▾

Edoxaban must be reduced from 60mg OD to 30mg OD if taken concomitantly with strong P-glycoprotein (P-gp) inhibitors such as Ciclosporin, Dronedarone, Erythromycin, or Ketoconazole. Mild P-gp inhibitors like Amiodarone, Verapamil, or Quinidine do not trigger an automatic reduction for Edoxaban (unlike Dabigatran).

What should happen if a patient's weight is over 120 kg? ▾

In patients weighing > 120 kg or with a BMI > 40 kg/m², evidence indicates that Apixaban and Rivaroxaban maintain reliable pharmacokinetics, whereas clinical efficacy data for Dabigatran and Edoxaban is more limited. Review local ICB formulary guidance and consider peak/trough anti-Xa monitoring or haematology advice if appropriate.

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