Pharmacokinetics of progesterone
Routes of administration
Table:
Route	Dose	Time	P4 (levels)	Allo (levels)	Preg (levels)	Assay

Oral (in oil, micronized)	100 mg 100 mg 100 mg 200 mg 200 mg 200 mg 300 mg 300 mg 600 mg 1,200 mg	2.7 hours ? ? 2.2 hours ? ? 2.0 hours ? ? ?	10.2 ng/mL 1.5–6.5 ng/mL 1.5–2.2 ng/mL 19.9 ng/mL 3.2–13.8 ng/mL 12 ng/mL 49.8 ng/mL 9.0–32.2 ng/mL 32.8 ng/mL 58.5 ng/mL	ND ND 14 ng/mL ND ND 30 ng/mL ND ND ND ND	ND ND 3.6 ng/mL ND ND 60 ng/mL ND ND ND ND	RIA ? LC–MS RIA ? RIA (+CS) RIA RIA RIA RIA

Vaginal	25 mg 50 mg 100 mg 100 mg 200 mg 400 mg	? ? ? ? 12 hours ?	7.3 ng/mL 8.8 ng/mL 9.5–19.0 ng/mL 5 ng/mL 5.2 ng/mL 16 ng/mL	ND ND ND 3.5 ng/mL ND 1.2 ng/mL	ND ND ND NC ND 0.3 ng/mL	? ? ? RIA (+CS) RIA RIA (+CS)

Rectal	25 mg 100 mg 200 mg	? ? ?	6.4 ng/mL 22.5 ng/mL 19.3–20.3 ng/mL	ND ND ND	ND ND ND	? ? ?

Intramuscular (in oil)	25 mg 50 mg 100 mg 200 mg	? ? ? ?	16.9 ng/mL 36.5 ng/mL 81.8–83.8 ng/mL 194–270 ng/mL	ND ND ND ND	ND ND ND ND	? ? ? ?

Notes: In the case of oral progesterone, RIA may overestimate levels of progesterone by as much as 8-fold due to its low specificity and cross-reactivity with high levels of progesterone metabolites.

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