Objectives: To measure and evaluate the in vitro release of MTX from suspensions of methotrexate (MTX) and lipiodol (LPD), and to investigate the MTX concentration and fertility rate using an animal model.
Methods: This study was divided into three components: a) An in vitro Release Study, b) Animal Study No. 1 (concentration of tissue and plasma levels), and c) Animal Study No. 2 (fertility rate after MTX suspension).
Result: The releasing rate in vitro was more rapid with MTX-S (MTX dissolved in saline) than with either MTX-LPD (MTX dissolved in lipiodol) or MTX-LPD-PC (MTX suspended in lipiodol and phosphatidylcholin, i.e., MTX suspension). The tissue concentration tended to be higher with an MTX suspension than with MTX-S. There was no significant difference in the fertility rate or the nidation index among the 3 groups (Groups 1, 2, and 3).
Conclusion: The injection of an MTX suspension is useful for increasing the tissue concentration and maintaining the long-term effectiveness of MTX, and this technique might offer a new approach in the treatment of ectopic pregnancy (EP) or in second-line therapy for persistent EP.