Published: May 2009

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Isotretinoin - indications and teratogenicity

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Prescriber Update 30(2): 7
May 2009

Isotretinoin is an oral retinoid indicated for the treatment of severe forms of nodulo-cystic acne, in particular cystic acne and acne conglobata. Isotretinoin is indicated in acne that is resistant to therapy. In order to judge its effectiveness in individual patients and reduce the chance of adverse reactions it should not be used with other acne treatments.

Changes to the funding of isotretinoin have widened access for patients to this highly effective therapy; therefore we are taking this opportunity to inform prescribers, who may be unfamiliar with the safety profile of isotretinoin, of its teratogenic effects.

Medsafe is aware that isotretinoin exposure has been responsible for a number of pregnancy terminations in recent years. If exposure to isotretinoin occurs during pregnancy there is a high risk of a deformed infant or foetal death, even if the exposure is only for a short period. Malformation rates of up to 30% are expected in women exposed to isotretinoin in the first trimester of pregnancy. This is compared to a baseline risk of malformation of 3 to 5% in the general population.¹

As a result of its teratogenicity isotretinoin is contraindicated in women of childbearing potential unless an extensive list of conditions for prescribing are met. For further information on the conditions associated with prescribing isotretinoin, please see the product data sheets at: www. medsafe.govt.nz/Medicines/infoSearch.asp

Internationally various strategies are used to reduce the risk of pregnancy exposure to isotretinoin. Strategies range from prescribing restrictions to extensive risk management systems such as the iPledge system used in the USA. However, the effectiveness of these strategies remains unproven as cases of isotretinoin exposure in pregnancy are still reported.

Medsafe is currently in the process of assessing the risk mitigation strategies used by the manufacturers of isotretinoin products in New Zealand and will advise prescribers of any action as necessary. In the meantime prescribers are reminded to:

• Assess risks and benefits before initiating or continuing isotretinoin treatment.
• Be aware of the conditions that patients need to meet before being treated with  isotretinoin.  These conditions include the use of at least one & preferably 2 complimentary forms of contraception (including a barrier method).
• Be aware of the risks associated with isotretinoin exposure during pregnancy.
• Report all adverse reactions to CARM.

Medsafe is aware that a decision support tool specifically designed for isotretinoin prescribing is now available through the Best Practice Advisory Centre New Zealand (BPAC). Please contact BPAC for further information.

Reference

1. Berard A, Azoulay L, Koren G, Blais L, Perreault S, Oraichi D. Isotretinoin, pregnancies, abortions and birth defects: a population-based perspective. Br J Clin Pharmacol. 2007; 63:196-205