Anti-nidatory effect of vaginally administered (Ala(8,13,8))-magainin II amide in the rhesus monkey

The hypothesis that timed application of a potent anti-microbial, anti-tumo r agent like magainin peptides can inhibit blastocyst implantation was exam ined in the present study using the rhesus monkey as the primate model. Inc idence of pregnancy, vaginal bleeding patterns, serum levels of progesteron e, estrogen and monkey chorionic gonadotropin were examined following vagin al administration of (Ala(8,13,18))-magainin II amide, a synthetic analogue of magainin 2, via tampon during days 20 to 26 of mated cycles. Implantati on occurred in two out of three animals following administration of 0.25 mg magainin, while administration of 0.5 mg (Ala(8,13,18))-magainin II amide resulted in inhibition of implantation in all females with no change in len gths of treatment cycles, and subsequent cycles. It appears from the presen t study that, besides being a local microbicidal agent, intravaginal admini stration of (Ala(8,13,18))-magainin II amide is a potential anti-implantati on strategy for intercepting pregnancy. (C) 2000 Elsevier Science Inc. All rights reserved.