Pharmacokinetics and Pharmacodynamics of Escalating Doses of SHetA2 After Vaginal Administration to Mice

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SHetA2 is a novel compound with strong potential to treat cervical dysplasia, but its low aqueous solubility limits its oral bioavailability. A vaginal suppository achieved SHetA2 cervix concentrations that were severalfold above the predicted therapeutic levels. Thus, we aimed at determining the minimum dose that would achieve SHetA2 therapeutic levels while reducing cyclin D1 levels, the pharmacodynamic end point. The disposition of SHetA2 after vaginal administration of escalating SHetA2 doses and the corresponding reduction in cyclin D1 levels was compared to that after the conventional oral treatment. Vaginal administration of a 15-mg/kg dose achieved an area under the cervix concentration versus time curve (AUCcervix) that was ∼120 times larger than that after a 60 mg/kg administered orally. AUCcervix and Cmax-cervix did not increase proportionally with respect to the dose, with the 30-mg/kg dose resulting in higher AUCcervix and Cmax-cervix (1368.53 μg.mL/h and 155.38 μg/g, respectively) compared to the 15 mg/kg (334.98 μg.mL/h and 121.78 μg/g, respectively) or 60 mg/kg (1178.55 μg.mL/h and 410.38 μg/g, respectively). Likewise, the 30-mg/kg dose caused a larger reduction in cyclin D1 levels than the other doses. Thus, the 30-mg/kg dose was selected for future efficacy studies in a mouse model of cervical neoplasia.