Febsan 40/Febsan 80 Drug Interactions

XO Substrate Drugs: Febuxostat is a XO inhibitor. Drug interaction studies of febuxostat with drugs that are metabolized by XO (e.g., theophylline, mercaptopurine, azathioprine) have not been conducted. Inhibition of XO by febuxostat may cause increased plasma concentrations of these drugs leading to toxicity. Febuxostat tablets are contraindicated in patients being treated with azathioprine, mercaptopurine or theophylline.
Cytotoxic Chemotherapy Drugs: Drug interaction studies of febuxostat with cytotoxic chemotherapy have not been conducted. No data are available regarding the safety of febuxostat during cytotoxic chemotherapy.
P450 Substrate Drugs: In vitro studies have shown that febuxostat does not inhibit P450 enzymes, CYP1A2, 2C9, 2C19, 2D6 or 3A4, and it also does not induce CYP1A2, 2B6, 2C9, 2C19 or 3A4 at clinically relevant concentrations. As such, pharmacokinetic interactions between febuxostat and drugs metabolized by these CYP enzymes are unlikely.
In vivo Drug Interaction Studies: Based on drug interaction studies in healthy subjects, febuxostat does not have clinically significant interactions with colchicine, naproxen, indomethacin, hydrochlorothiazide, warfarin or desipramine. Therefore, Febuxostat tablets may be used concomitantly with these medications without any dose adjustments.
Effect of Other Drugs on Febuxostat: Febuxostat is metabolized by conjugation and oxidation via multiple metabolizing enzymes. The relative contribution of each enzyme isoform is not clear. Drug interactions between febuxostat and a drug that inhibits or induces one particular enzyme isoform is, in general, not expected.
Renal Impairment: No dose adjustment is necessary in patients with mild or moderate renal impairment (Clcr 30-89 mL/min). The recommended starting dose of Febuxostat tablets is 40 mg once daily. For patients who do not achieve a sUA <6 mg/dL after 2 weeks with 40 mg, Febuxostat tablets 80 mg is recommended.
There are insufficient data in patients with severe renal impairment (Clcr <30 mL/min); therefore, caution should be exercised in these patients.
Hepatic Impairment: No dose adjustment is necessary in patients with mild or moderate hepatic impairment (Child-Pugh Class A or B). No studies have been conducted in patients with severe hepatic impairment (Child-Pugh Class C); therefore, caution should be exercised in these patients.