Gout When Allopurinol Fails in Patients on Strong P-glycoprotein and/or CYP3A4 Inhibitors
Clinical scenario
This protocol addresses patients with gout who are concurrently receiving strong P-glycoprotein and/or CYP3A4 inhibitors — such as cyclosporin, clarithromycin, ketoconazole, or verapamil — and in whom the previous urate-lowering regimen did not achieve serum uric acid targets.
Critical interaction constraint: Colchicine must not be co-prescribed with strong P-glycoprotein and/or CYP3A4 inhibitors. These agents increase colchicine plasma concentration, creating serious risk of adverse effects. This constraint directly shapes prophylaxis and agent selection in this population.
Why this protocol is needed — prior line did not succeed
The previous treatment approach — allopurinol with dose titration and lifestyle measures — failed to achieve the required serum uric acid targets: <6 mg/dL (360 mmol/L) maintained lifelong, or <5 mg/dL (300 mmol/L) for patients with severe gout. This failure of allopurinol to reach target is the trigger for escalation to a different urate-lowering strategy.
Next-line approach (partial): When allopurinol cannot achieve serum uric acid targets in patients on these interacting medications, the protocol involves switching to an alternative urate-lowering agent — such as febuxostat or a uricosuric — or adopting a combination strategy. The complete agent selection criteria, sequencing, and monitoring guidance are in the full protocol.
Treatment targets
- Serum uric acid <6 mg/dL (360 mmol/L), maintained lifelong
- Serum uric acid <5 mg/dL (300 mmol/L) for patients with severe gout (tophi, chronic arthropathy, frequent attacks), until total crystal dissolution
References
DOI: 10.1136/annrheumdis-2016-209707
- Colchicine should not be given to patients receiving strong P-glycoprotein and/or CYP3A4 inhibitors such as cyclosporin or clarithromycin.
- Co-prescription of colchicine with strong P-glycoprotein and/or CYP3A4 inhibitors should be avoided.
- A pharmacokinetic study showed that strong P-glycoprotein and/or CYP3A4 inhibitors such as cyclosporin, clarithromycin, verapamil and ketoconazole when prescribed with colchicine increased colchicine plasma concentration, thereby exposing patients to risk of serious side effects.
- If the SUA target cannot be reached by an appropriate dose of allopurinol, allopurinol should be switched to febuxostat or a uricosuric, or combined with a uricosuric.
- Febuxostat is a potent non-purine selective XOI approved at daily doses of 80 and 120 mg in Europe.
- Benzbromarone (50–200 mg/day) is a more potent uricosuric as compared with probenecid (1–2 g/day).
- For patients on ULT, SUA level should be monitored and maintained to <6 mg/dL (360 mmol/L).
- A lower SUA target (<5 mg/dL; 300 mmol/L) to facilitate faster dissolution of crystals is recommended for patients with severe gout (tophi, chronic arthropathy, frequent attacks) until total crystal dissolution and resolution of gout.
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