COMPARATIVE-STUDY OF PROGESTERONE PLASMA-LEVELS AFTER NASAL SPRAY AND INTRAMUSCULAR ADMINISTRATION OF NATURAL PROGESTERONE IN MENOPAUSAL WOMEN

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 C(Max) 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 C(Max) of 4.137 ng/ml at T(Max) = 240 min, the AUC0-720 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.