Anticoagulants: The Dispensing Safety Checklist

📋 First Dispense Essentials

Mandatory items to issue

• Warfarin: issue the yellow anticoagulant treatment booklet and ensure the patient understands the importance of carrying it to all appointments and monitoring visits.
• DOACs (apixaban, rivaroxaban, dabigatran, edoxaban): issue an anticoagulant patient alert card appropriate to the prescribed medicine and local practice.
• Ensure the patient has a clear written record of their current dose and indication.

Baseline clinical checks

• Warfarin: baseline international normalised ratio (INR), full blood count, renal function, liver function tests, and blood pressure.
• DOACs: renal function before starting, assessed using Cockcroft-Gault creatinine clearance rather than eGFR alone. eGFR may overestimate renal function and increase bleeding risk. Also check full blood count, liver function tests, serum creatinine, and urea and electrolytes at baseline.
• Liver function should be assessed before starting any DOAC. Significant hepatic disease associated with coagulopathy may affect suitability.
• Weight should be documented, as body weight may influence dose selection for some DOACs.
• Confirm the indication (atrial fibrillation, venous thromboembolism, or other) as this determines dose and duration.
• DOAC dose suitability: verify the prescribed dose is appropriate for the indication, Cockcroft-Gault creatinine clearance, age, body weight, serum creatinine, liver function, and any interacting medicines. Refer to the current Summary of Product Characteristics or BNF for dose thresholds.
• Confirm there is no mechanical heart valve or other absolute contraindication to DOAC therapy. Warfarin remains the anticoagulant of choice for patients with mechanical heart valves.

Key risks and lifestyle traps

• Warfarin and antibiotics: metronidazole, fluconazole, erythromycin, ciprofloxacin, trimethoprim, and co-trimoxazole can significantly increase INR and bleeding risk. INR should be checked 3 to 5 days after starting, or per the anticoagulant clinic or local protocol. Check for monitoring arrangements and contact the prescriber if required.
• Warfarin and non-steroidal anti-inflammatory drugs (including ibuprofen): avoid where possible due to increased bleeding risk.
• Large or sudden increases in cranberry consumption may affect INR. Advise patients to keep dietary intake consistent and report unusual bleeding.
• Warfarin and green leafy vegetables (spinach, kale, broccoli): consistent intake is acceptable, but sudden large dietary changes may affect anticoagulation control.
• St John's Wort: can reduce DOAC levels and increase thrombosis risk. Avoid with DOACs.
• DOACs and strong cytochrome P450 3A4 or P-glycoprotein inhibitors (for example ketoconazole, clarithromycin, or ritonavir) may increase bleeding risk.
• Rivaroxaban (15mg and 20mg doses): must be taken with food to ensure adequate absorption. Taking without food significantly reduces bioavailability and may reduce anticoagulant effect.
• Dabigatran capsules must be swallowed whole and not opened, crushed, or chewed. Opening the capsule significantly increases absorption and bleeding risk.
• Alcohol increases bleeding risk with all anticoagulants. Heavy binge drinking can also destabilise INR control in patients taking warfarin.
• Pregnancy: warfarin is teratogenic and DOACs are generally avoided during pregnancy. Refer urgently if a patient is pregnant or planning pregnancy.
• Renal function decline: all DOACs depend partly on renal clearance. Dabigatran is particularly affected. Acute illness causing dehydration may increase drug exposure and bleeding risk.

First dispense script

🔄 Repeat Dispense Screen

Mandatory documentation

• Warfarin: record the current INR value, the date it was taken, the current weekly dose, and the target INR range on the dispensing record.
• DOACs: record the date of the last renal function review and flag if overdue.
• Document any new interacting medicines added since the previous dispense.
• Escalation: if a recent INR is unavailable, renal monitoring is overdue, a new interacting medicine has been added, a wrong dose or missed-dose pattern is suspected, or the patient reports new bleeding symptoms, escalate to the prescriber or anticoagulant service urgently. Where supply continuity is clinically necessary, follow local standard operating procedure, emergency supply rules, and document the risk assessment.

Ongoing clinical checks

• Warfarin: INR monitoring at least every 12 weeks in stable patients, and more frequently after dose changes, interacting medicines, or illness.
• DOACs: renal function at least annually in all patients. More frequent monitoring is needed in older or frail patients, known renal impairment, intercurrent illness (particularly dehydration or acute kidney injury), or when interacting medicines are added.
• Apixaban and rivaroxaban: review dosing if renal function has deteriorated.
• Annual weight review may be helpful where body weight influences dose selection.
• Consider periodic liver function monitoring in accordance with local protocols and clinical circumstances.

Ask the patient at the counter

• "Have you had any unusual bleeding since your last prescription, such as cuts that would not stop, unexplained bruising, blood in your urine, or black stools?"
• "Have you started any new medicines, including aspirin, clopidogrel, an SSRI or SNRI antidepressant, an oral steroid, antibiotics, anti-inflammatory medicines, supplements, or herbal remedies since we last spoke?"
• "Have you missed any doses, taken extra doses, or changed when you take it? Have you had vomiting, diarrhoea, dehydration, or an acute illness since your last supply?"

Lifestyle and surgical alerts

• Surgery and invasive procedures: patients must inform their surgeon and anaesthetist. Interruption should only occur under specialist guidance. Some warfarin patients may require bridging therapy depending on indication and thrombotic risk.
• Dental treatment: patients must inform their dentist. Many dental procedures can be performed without stopping anticoagulation. The Scottish Dental Clinical Effectiveness Programme (SDCEP) provides guidance on managing anticoagulated patients in dental practice.
• Falls risk: if a patient reports recurrent falls, consider referral for review of the risks and benefits of ongoing anticoagulation.
• Alcohol: consistent moderate intake is preferable to irregular heavy drinking. Binge drinking increases bleeding risk.
• Professional boundary: anticoagulant dose adjustments, bridging therapy, or decisions to stop and restart anticoagulation should not be made independently by community pharmacy outside an authorised protocol. Always refer to the prescribing team or anticoagulant service.

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