17-OHPC in Pregnancy: IM vs SC Routes

17-hydroxyprogesterone caproate (17-OHPC) is used in women with a prior preterm birth (PTB) as it reduces recurrences by a third. The drug is administered intramuscularly (IM) but that creates discomfort and in many instances requires repeated office visits as the drug is administered weekly from 16-20 weeks until 36 weeks or delivery. AMAG Pharmaceuticals obtained FDA approval to administer the drug subcutaneously (SC) based on demonstration of bioequivalence of a dose of 275 mg SC to a dose of 250 mg IM. That bioequivalence study was performed in postmenopausal women who received a single dose. This study will be performed in pregnant women with repeated injections both to demonstrate that equivalent exposure is seen and to assess the side effects and acceptance of each route of administration.

A pharmacokinetic (PK) study will be performed after participants have reached steady state (after 9 injections). Participants will receive their injections from research personnel up until the time of completion of the PK study. Home injections will be an option for all participants after the PK study is completed.