What is known about the safety of Suprecur (buserelin) during pregnancy, following inadvertent expo

Fråga: What is known about the safety of Suprecur (buserelin) during pregnancy, following inadvertent exposure during in-vitro fertilization?

Sammanfattning: Data on buserelin during pregnancy is limited. The majority of the pregnancies reported (about 80 per cent) ended up with healthy infants. None produced a malformed child. To date the documentation is still insufficient to allow proper evaluation of teratogenicity, however, the exposure to buserelin does not appear to be an indication for terminating a successful pregnancy after a long history of infertility.

Svar: Buserelin is a synthetic analog of the body´s own gonadotropin releasing hormone (GnRH). It is 16-40 times biologically more potent than the body´s GnRH. Buserelin possesses a high affinity for the pituitary´s GnRH-receptors. Initially it stimulates and then suppresses the production of gonadotropin by occupying the receptors which become refractory to further stimulation "down regulation phenomenon". This leads to a reduction of oestrogen and progesterone production by the ovaries. This action has been utilised therapeutically for the treatment of endometriosis and in in-vitro fertilization (1).

During in-vitro fertilization one uses this principle of down regulation of GnRH production to avoid premature luteinization and spontaneous ovulation. Buserelin is usually given in the form of nasal spray and treatment starts on day 21 of the menstrual cycle. The disadvantage of this protocol is that the patient may have conceived in this cycle and the fetus gets exposed to the drug (2).

In FASS buserelin is characterised as category B. Fetal deformities such as the ossification of the skeleton, lower birth weights and short stature were observed in experimental animals. However, the clinical relevance of these effects in man is unknown (1).

In a Medline search, we could find however five articles describing the outcome of a total of 55 pregnancies following inadvertent exposure to buserelin (2-5). Of these, 42 ended up with healthy infants, ten aborted while three patients with tubal disease had an ectopic pregnancy. No teratogenic effects were reported in any of the infants. The conclusion from these studies was that although the data is still too scarce to make proper assessment, the usage of buserelin does not appear to be an indication for termination of pregnancy in patients with long term infertility.

In another study where 42 woman treated with buserelin for endometriosis were followed up, 23 became pregnant. The 23 pregnancies ended up with 18 healthy children, four abortions and one ectopic pregnancy (6). In a case report, a woman with endometriosis and unilateral tubal patency who became pregnant on her first treatment cycle with buserelin delivered healthy twins (7).