Date: 5 April 2017
Concomitant use of liver enzyme inducers—mainly inducers of CYP3A4 enzymes—increases the metabolism of levonorgestrel. This results in a decrease in plasma levonorgestrel levels, which may reduce the contraceptive efficacy of levonorgestrel-containing emergency hormonal contraceptives. Women seeking emergency contraception who have used an enzyme-inducing medicine within the last 4 weeks, are advised to use a non-hormonal emergency contraceptive, i.e. a copper intrauterine device (Cu-IUD). If this is not an option, they should be advised to double the usual dose of levonorgestrel from 1.5 mg to 3 mg to compensate for the reduction in plasma levonorgestrel levels. The information on the medicine’s outer carton and package insert will be revised to include the new dosing instructions for this category of women. A Direct Healthcare Professional Communication (DHPC) has been issued by Medispec (M) Sdn. Bhd. in agreement with NPRA to highlight this updated information.