Clinical disposition, metabolism and in vitro drug-drug interaction properties of omadacycline.

1. Absorption, distribution, metabolism, transport and elimination properties of omadacycline, an aminomethylcycline antibiotic, were investigated in vitro and in a study in healthy male subjects. 2. Omadacycline was metabolically stable in human liver microsomes and hepatocytes and did not inhibit or induce any of the nine cytochrome P450 or five transporters tested. Omadacycline was a substrate of P-glycoprotein, but not of the other transporters. 3. Omadacycline metabolic stability was confirmed in six healthy male subjects who received a single 300 mg oral dose of [C]-omadacycline (36.6 μCi). Absorption was rapid with peak radioactivity (∼610 ngEq/mL) between 1-4 h in plasma or blood. The AUC of plasma radioactivity (only quantifiable to 8 h due to low radioactivity) was 3096 ngEq h/mL and apparent terminal half-life was 11.1 h. Unchanged omadacycline reached peak plasma concentrations (∼563 ng/mL) between 1-4 h. Apparent plasma half-life was 17.6 h with biphasic elimination. Plasma exposure (AUC) averaged 9418 ng h/mL, with high clearance (CL/F, 32.8 L/h) and volume of distribution (Vz/F 828 L). No plasma metabolites were observed. 4. Radioactivity recovery of the administered dose in excreta was complete (>95%); renal and fecal elimination were 14.4% and 81.1%, respectively. No metabolites were observed in urine or feces, only the omadacycline C4-epimer.