USA – FDA releases draft guidance for drug interaction studies with combined oral contraceptives

The US Food and Drug Administration (FDA) has issued draft guidance for industry on performing clinical studies to look at the potential interactions between an investigational drug and combined oral contraceptives.

Interactions with other therapies can impact the efficacy and safety of combined oral contraceptives by affecting the enzymes involved in metabolizing progestins and estrogens. “For example, decreased progestin concentrations can lead to unintended pregnancy (loss of efficacy), whereas increased estrogen and/or progestin concentrations can increase the risk of venous thromboembolisms (VTEs), a rare but severe adverse event,” the agency wrote in the draft guidance.
 
The agency has issued previous guidance on studies related to cytochrome P450 enzyme- and transporter-mediated drug interactions. The current guidance drills down on recommendations for metabolism-based drug interactions with combined oral contraceptives, which usually contain two synthetic steroid hormones – a progestin and an estrogen. (RELATEDDrug-Drug Interactions: FDA Issues Guidance on Clinical, In Vitro Studies, Regulatory Focus, 23 January 2020,)…