Major
Colchicine × tacrolimus
Antigout agents×Calcineurin inhibitor (immunosuppressant)
Mechanism
Tacrolimus and colchicine are both P-glycoprotein substrates. Competition at this transporter raises colchicine levels, especially in transplant patients with borderline renal function.
Symptoms
Profuse diarrhoea, vomiting, abdominal pain. With prolonged combination: muscle weakness, peripheral neuropathy, falling leukocytes and platelets. In transplant patients: accelerated graft decline.
Management
For acute gout in transplant patients, a short colchicine course (3–5 days) at 0.3 mg every other day with muscle symptom and blood count monitoring. For chronic gout, allopurinol. For acute attacks, intra-articular glucocorticoid.