Date: 15 March 2017
The metabolism of levonorgestrel is known to be increased by concomitant use of liver enzyme inducers, mainly inducers of CYP3A4 enzymes. This resulting reduction in plasma levonorgestrel levels may reduce 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 is being revised to include the new dosing instructions for this category of women. For further details on this updated advice, please refer to the Direct Healthcare Professional Communication (DHPC) issued by Pahang Pharmacy Sdn. Bhd. in agreement with NPRA.