What is the standard dose for progesterone (a progestin hormone) oil injection in a female patient of reproductive age?

Standard Dose for Progesterone Oil Injection

For progesterone in oil (intramuscular injection), the FDA-approved standard dose is 5-10 mg daily for 6-8 consecutive days for amenorrhea, or 5-10 mg daily for 6 days for functional uterine bleeding. 1

FDA-Approved Dosing Regimens

For Amenorrhea

• 5-10 mg intramuscularly daily for 6-8 consecutive days 1
• Withdrawal bleeding expected 48-72 hours after the last injection if sufficient ovarian activity has produced a proliferative endometrium 1
• May be followed by spontaneous normal cycles 1

For Functional Uterine Bleeding

• 5-10 mg intramuscularly daily for 6 doses 1
• Bleeding expected to cease within 6 days 1
• When combined with estrogen therapy, progesterone is begun after 2 weeks of estrogen treatment 1
• If menstrual flow begins during progesterone injections, discontinue the injections 1

Important Clinical Context

Progesterone oil injections are NOT the preferred route for hormone replacement therapy in reproductive-age women. The guidelines consistently recommend oral or vaginal micronized progesterone as first-line due to superior safety profiles. 2, 3, 4

Preferred Alternative Routes for HRT

• Oral micronized progesterone: 200 mg daily for 12-14 days per month (sequential regimen) or 100 mg daily continuously 2, 4
• Vaginal micronized progesterone: 200 mg daily for 12-14 days per month as an alternative with good endometrial protection 2
• These routes have lower cardiovascular and thrombotic risk compared to intramuscular formulations 2, 3

Critical Caveats

Injection Site Considerations

• Progesterone in oil is irritating at the injection site, which is a significant disadvantage compared to other administration routes 1
• Research shows intramuscular progesterone causes significantly more side effects (moderate-to-severe) compared to oral or vaginal routes 5

Pharmacokinetic Differences

• Intramuscular progesterone achieves peak serum levels at approximately 7 hours post-injection 6
• This results in higher systemic exposure but paradoxically lower endometrial tissue concentrations compared to vaginal administration 7
• Steady state is reached within 48 hours with intramuscular administration 7

When IM Progesterone May Be Indicated

• Acute treatment of amenorrhea or dysfunctional uterine bleeding when rapid intervention is needed 1
• Situations where oral or vaginal compliance is not feasible
• Note: Injectable 17-alpha-hydroxyprogesterone caproate (17P) 250 mg IM weekly is a different formulation specifically for preterm birth prevention, not general progesterone replacement 4