Dimethyl Fumarate and Oral Contraceptives: Drug Interactions Explored

Certain combined OCs may be used with DMF without a need for dose modification
Certain combined OCs may be used with DMF without a need for dose modification

Norgestimate/ethinyl estradiol-based oral contraceptives (OC) may be taken with delayed-release dimethyl fumarate (DMF) without dose adjustment, according to findings from a new study published in Clinical Pharmacology in Drug Development. 

Delayed-release DMF exerts anti-inflammatory and neuroprotective properties for the treatment of relapsing multiple sclerosis, a disease that often develops in women between the ages of 20 and 40. "Because women of childbearing potential are advised by regulatory agencies to use effective contraception during DMF treatment, it is important to evaluate whether hormonal oral contraception (OC) are reliable when combined with DMF treatment," the authors write.

To evaluate the potential drug-drug interaction between DMF given 240mg twice daily and a combination OC (norgestimate 250mcg, ethinyl estradiol 35mcg), 46 healthy women were enrolled with 32 completing the study. 

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Following the lead-in period (OC alone), patients were randomized to:

  • Sequence 1: OC and DMF co-administered in Period 1; OC alone in Period 2
  • Sequence 2: OC alone in Period 1; OC and DMF co-administered in Period 2

Study authors evaluated the mean concentration profiles of plasma norelgestromin and ethinyl estradiol. "Low serum progesterone levels during combined treatment confirmed suppression of ovulation," noted lead author Bing Zhu. Overall, the pharmacokinetics of DMF (measured by monomethyl fumarate) proved consistent with historical data when DMF was given alone. Also, the authors did not observe any new safety concerns. 

Findings from the study suggest that certain combined OCs may be used with DMF without a need for dose modification, the authors concluded.

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