Comparative Study of Progesterone Plasma Levels after Nasal Spray and Intramuscular Administration of Natural Progesterone in Menopausal Women

Abstract

11 mg natural progesterone (P) was administered to 20 healthy menopausal women by means of a nasal spray or intramuscular injection. Circulating P levels were calculated at various times after administration. The spray formulation yielded a CMax of 3.75 ng/ml at T_Max = 60 min, the area under the curve (AUC)_0–720 being 1,481.6 ± 343. Intramuscular administration yielded a mean Cm3x of 4.137 ng/ml at T_Max = 240 min, the AUC_0–720 being 2,491.2 ± 540. P absorption was faster through the nasal than through the intramuscular route, but intramuscular administration led to high serum levels for a much longer period.

The role of progesterone in prevention of preterm birth

“…Current information about the pharmacokinetics of progesterone relates to its use in assisted reproduction,87–90 in menopausal91 and post-menopausal women,88 92 and in women with endometrial carcinoma 93. These studies indicate blood progesterone concentrations following vaginal administration to be lower than after intramuscular administration 89,90.…”

Progesterone supplementation for preventing preterm birth: a systematic review and meta‐analysis

“…Our meta‐analysis was unable to inform the optimal route of administration, with only a single study reporting vaginal use of progesterone (23). Available pharmacokinetic data for progesterone relate to its use in other areas of women's health care, including assisted reproduction (39–42), in menopausal women (43), post‐menopausal women (44, 45), and in women with endometrial carcinoma (46). Serum progesterone levels following vaginal administration are lower than those after intramuscular administration (41, 42).…”

Perimenopausal and postmenopausal hormone replacement therapy*Part 2. Hormonal Regimens and Complementary and Alternative Therapies

“…Progestin can be delivered as a nasal spray (42–44), by intramuscular injection (45), and via an intrauterine device (IUD) (46), although none of these delivery systems are currently in widespread use. Additional studies are needed on the efficacy and safety of these routes.…”