 It has also been found to have direct antiproliferative effects on human ovarian cancer cells "in vitro".Gestonorone caproate has been reported to act to some extent as a 5α-reductase inhibitor, similarly to progesterone.Like the closely related progestins hydroxyprogesterone caproate and 19-norprogesterone, gestonorone caproate shows poor activity orally and must be administered parenterally; specifically, via intramuscular injection.