The Missed Dose at the Dialysis Unit
A 68-year-old man with stage 4 chronic kidney disease (eGFR 22 mL/min/1.73 m2) attends a hospital outpatient clinic. He has type 2 diabetes, hypertension, and atrial fibrillation. His current medicines are metformin 1 g twice daily, ramipril 10 mg daily, atorvastatin 40 mg nightly, warfarin 5 mg daily (INR stable at 2.4), and ibuprofen 400 mg three times daily for knee pain, which he has taken for six weeks. He reports increasing fatigue, reduced urine output, and one episode of dark stools. His latest bloods show creatinine risen from 180 to 265 micromol/L, potassium 5.6 mmol/L, and haemoglobin 98 g/L. He asks the pharmacist whether he should just stop the ibuprofen and keep everything else the same until his next appointment in three weeks.
1. Which of his medicines are contributing to his current presentation, and what is the pharmacological reasoning for each?
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Ibuprofen is the leading culprit: an NSAID inhibits prostaglandin-mediated afferent arteriolar vasodilation, reducing renal perfusion, and this is amplified by the ACE inhibitor (ramipril), which dilates the efferent arteriole. Together they can cause an acute-on-chronic decline in eGFR and hyperkalaemia. The rising creatinine and potassium fit this 'triple whammy' pattern (NSAID plus ACE inhibitor, with volume depletion as the third factor). Ibuprofen also causes gastric mucosal injury and, with warfarin, markedly increases gastrointestinal bleeding risk, which fits the dark stools and falling haemoglobin. Metformin is a concern at eGFR 22 because reduced clearance raises the risk of lactic acidosis; it should be reviewed and generally stopped below an eGFR of about 30. Ramipril itself is not automatically wrong in CKD but needs review in the context of the acute deterioration and hyperkalaemia. Warfarin is not causing the renal injury, but the bleeding episode requires urgent assessment of INR and haemoglobin.
2. He proposes stopping only the ibuprofen. Why is that insufficient, and what should the pharmacist recommend instead?
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Stopping ibuprofen is necessary but not sufficient because the damage is already established and other risks remain unaddressed. The pharmacist should recommend same-day clinical review rather than waiting three weeks: the falling haemoglobin with dark stools needs urgent assessment (full blood count, INR, consideration of endoscopy), and the potassium of 5.6 with a creatinine of 265 needs repeat measurement and management. Metformin should be stopped or at least suspended pending review. Ramipril should be discussed with the prescriber rather than unilaterally stopped, but the combination with an NSAID must not continue. Analgesia should be substituted with paracetamol at an appropriate dose, with attention to total daily dose in renal impairment, and non-drug measures. Warfarin requires INR check and review of interacting medicines and of the bleeding source. The pharmacist should not simply agree to a plan that leaves a potentially bleeding patient at home for three weeks.
3. How should the pharmacist document and communicate this intervention, and what follow-up is needed?
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Document the specific findings (eGFR fall, potassium, haemoglobin, dark stools, NSAID duration), the medicines implicated, the recommendation made, and the response of the prescriber and patient. Use a structured referral or intervention note and, if the pharmacy has one, a yellow-card or local adverse drug reaction report for the NSAID-related renal and bleeding event. Communication should be direct and contemporaneous: telephone the prescriber or clinic rather than relying on a letter, then confirm in writing. Give the patient clear safety-netting advice: what to do if bleeding worsens, when to seek emergency care, and which medicines to stop now versus which to continue until told otherwise. Follow-up should confirm that ibuprofen has actually stopped, that metformin has been reviewed, that repeat renal function and potassium have been done, and that analgesia has been addressed. Record the counselling given and the patient's understanding.