Colchicine is metabolised by CYP3A4 and is a substrate of P-gp. Coadministration is expected to increase colchicine concentrations. A reduction in colchicine dosage or an interruption of colchicine treatment is recommended in patients with normal renal or hepatic function if treatment with Symtuza is required. The US product label for Symtuza gives the following dose modifications. For treatment of gout flares, the recommended dosage is 0.6 mg (1 tablet) for 1 dose, followed by 0.3 mg (half tablet) 1 hour later. The dose is to be repeated no earlier than 3 days. For prophylaxis of gout flares, if the original regimen was 0.6 mg twice a day, the regimen should be adjusted to 0.3 mg once a day; if the original regimen was 0.6 mg once a day, the regimen should be adjusted to 0.3 mg once every other day. For treatment of familial Mediterranean fever (FMF) do not exceed a maximum daily dose of 0.6 mg (may be given as 0.3 mg twice a day). Note, coadministration is contraindicated in patients with renal and/or hepatic impairment due to potential for serious and/or life-threatening reactions.