Progesterone Elimination Time from the Body
Progesterone is cleared from the body within approximately 24–96 hours after discontinuation, depending on the route of administration and formulation. 1
Oral Micronized Progesterone Clearance
- Peak serum concentrations occur within 2–4 hours after oral administration of micronized progesterone 1, 2, 3
- Elimination half-life is relatively short, with progesterone concentrations declining rapidly after peak levels 1
- After a single 100 mg oral dose, progesterone remains elevated for at least 96 hours (4 days), though concentrations progressively decline during this period 2
- With twice-daily dosing (100 mg morning, 200 mg evening), plasma concentrations of the active metabolite 20α-dihydroprogesterone remain elevated at approximately 20 nmol/L for at least 12 hours after administration 3
Metabolite Clearance Timeline
- Pregnanediol-3α-glucuronide (the primary metabolite) shows the most sustained elevation, with peak values lasting approximately 6 hours after the final dose 2
- 20α-dihydroprogesterone (a biologically active metabolite) demonstrates a plasma profile that closely approximates progesterone itself, though with lower peak values 2, 3
- Progesterone metabolites are eliminated mainly by the kidneys as glucuronide and sulfate conjugates, with some undergoing enterohepatic recycling 1
Vaginal Progesterone Clearance
- Vaginal administration of 200–400 mg every 12 hours maintains serum progesterone at physiological midluteal levels with no significant reduction between 4 and 12 hours after administration, suggesting slow-release kinetics 4
- The wax suppository base leads to sustained absorption compared to oral formulations 4
Injectable Progesterone (Depot Medroxyprogesterone Acetate) Clearance
- Depot medroxyprogesterone acetate acts for approximately 15 weeks (3.5 months) after a single injection 5
- The median delay to conception after discontinuation is approximately 5.5 months plus the 15-week duration of effect, totaling around 9 months for complete clearance and return of fertility 5
- This represents a fundamentally different clearance profile than oral or vaginal progesterone due to the depot formulation 5
Clinical Implications for Contraceptive Progesterone
Progestin-Only Pills
- Backup contraception is required for 2 consecutive days if a dose is missed by more than 3 hours (>27 hours since previous dose) 6
- This short window reflects the rapid clearance of oral progestin formulations 6
Intramuscular Progesterone for Luteal Support
- In IVF cycles using 50 mg IM progesterone daily, most patients (67%) begin bleeding within 16.2 ± 2.6 days after oocyte retrieval despite continued progesterone treatment, suggesting functional clearance or receptor desensitization 7
- A minority (33%) maintain elevated progesterone levels and delayed bleeding beyond 17 days, indicating individual variation in metabolism 7
Factors Affecting Clearance
- Hepatic metabolism is the primary route, with progesterone metabolized largely to pregnanediols and pregnanolones 1
- Cytochrome P450 3A4 inhibitors (such as ketoconazole) may increase bioavailability and potentially prolong clearance, though clinical relevance is unknown 1
- Protein binding (96–99% bound to serum albumin and transcortin) affects distribution but not elimination kinetics 1
- The pharmacokinetics in patients with hepatic or renal insufficiency have not been formally studied, though renal excretion is the primary elimination pathway for metabolites 1
Practical Considerations
- For emergency contraception planning, progesterone-containing contraceptives require 7 consecutive days of backup contraception after missed doses of ≥48 hours 6
- When discontinuing progesterone for endometrial protection in hormone replacement therapy, withdrawal bleeding typically occurs within 3 weeks if pregnancy has not occurred 6
- Food increases bioavailability of oral progesterone, which may affect both peak levels and clearance patterns 1