From the FDA Drug Label
When the patient is switching from a 21-day regimen of tablets, she should wait 7 days after her last tablet before she starts levonorgestrel and ethinyl estradiol tablets. The FDA drug label does not answer the question about switching from Marvelon 21 to Tri-Cyclen 28, as the label only discusses switching to levonorgestrel and ethinyl estradiol tablets, not from Marvelon (Desogestrel and Ethinyl Estradiol) 21 to Tri-Cyclen (Norgestimate and Ethinyl Estradiol) 28. The FDA drug label does not answer the question.
From the Research
No washout period is necessary when switching from Marvelon 21 to Tri-Cyclen 28, as continuous hormone coverage is preferred to maintain contraceptive efficacy and prevent unintended pregnancy. You should start Tri-Cyclen 28 the day after taking the last active pill of Marvelon 21, without taking a break between the two medications. Both medications contain ethinyl estradiol as the estrogen component, though Tri-Cyclen has a slightly higher dose and uses norgestimate instead of desogestrel as the progestin.
When switching between combined hormonal contraceptives like these, it is essential to maintain continuous hormone coverage to prevent the risk of ovulation and unintended pregnancy 1. The study by 1 compared the effects of extending the pill-free interval on follicular activity in women taking oral contraceptives, which supports the idea of continuous hormone coverage.
Some key points to consider when switching from Marvelon 21 to Tri-Cyclen 28 include:
- Tri-Cyclen 28 contains 7 inactive pills compared to Marvelon 21's pill-free week, so it is crucial to follow the new pill pack's instructions carefully.
- If you miss the transition between packs, use a backup contraceptive method for 7 days after restarting.
- The pharmacokinetics of ethinyl estradiol are independent of the concomitantly administered progestin, as shown in the study by 2.
- Marvelon has been shown to be well-tolerated and effective in preventing pregnancy, with a Pearl Index of 0.0, as reported in the study by 3.
Overall, the direct switch from Marvelon 21 to Tri-Cyclen 28 without a washout period is recommended to maintain continuous hormone coverage and prevent unintended pregnancy.