Objective: To investigate embryotoxic potential and effects on human sperm motility of the mixed vasopressin V(1a)/oxytocin receptor antagonist atosiban considered for novel indication of improvement of uterine receptivity in embryo-transfer recipients.
Design: One-cell rabbit embryo bioassay and human sperm motility bioassay were performed in control media or in media containing atosiban.
Setting: Private center of reproductive medicine and academic research institute of reproduction biotechnology.
Animal(s): Rabbit females (New Zealand and California, N = 15) aged 4.5-6.5 months.
Intervention(s): In vitro exposure of one-cell rabbit embryos and human sperm to atosiban in the range of therapeutic concentrations clinically occurring in human beings.
Main outcome measure(s): Embryo development and sperm motility.
Result(s): Preimplantation development of one-cell rabbit embryos was not affected by atosiban in the concentrations < or =15,000 nM, which was 50-fold higher than the mean plasma concentration reached during regular therapy (300 nM). Atosiban did not affect human sperm motility in concentrations of < or =3,000 nM, in other words, 10 times the human mean plasma concentration.
Conclusion(s): Clinical application of atosiban in the proposed indication may be safe for embryos because it is compatible with preimplantation rabbit embryo development and human sperm motility.