Administering Tadalafil during delivery is safe for both mothers and newborns. The consistent levels of Tadalafil in the bloodstream support the effectiveness of administering it every 12 hours.

The objective of this phase I clinical study was to examine the safety and effectiveness of Tadalafil in shielding the fetus from hypoxic stress due to repetitive labor pains during childbirth and in evading fetal hypoxic-ischemic encephalopathy.

Employing a three-case cohort strategy, the researchers monitored the administration of 10 mg of Tadalafil to three patients, observing any vital adverse effects. Subsequently, with no serious adverse effects linked to Tadalafil, as determined by the Safety Evaluation Committee, three additional volunteers were incorporated and treated with a dosage of 20 mg. Blood levels of Tadalafil were documented prior to and after administration at 2, 4, 8, and 12-hour intervals, as well as 2 hours post-delivery.

A total of 7 subjects were recruited, with Tadalafil administered to six after excluding one subject who delivered prematurely before 37 weeks. Maternal adverse effects were deemed acceptable, with grade 1 headaches, myalgia, and anorexia observed, along with no obstetrical complications post-delivery at both dosage levels.

No grave adverse effects in neonates were linked with Tadalafil. The blood levels of Tadalafil remained consistent across both dosages. Moreover, while the level of soluble fms-like tyrosine kinase-1 remained unchanged, the placental growth factor displayed considerable variation prior to and after Tadalafil usage.

The study affirmed the safety of Tadalafil administration during childbirth for both fetus and the mothers. Stable blood levels of Tadalafil supported the efficiency of the administered regimen at 12-hour intervals. These results lay the groundwork for phase II trials aimed at further substantiating Tadalafil's optimal dosage and safety.