What is the recommended dosage of norgestimate (Lo Loestrin) for progesterone replacement?

Norgestimate Dosage for Progesterone Replacement

Lo Loestrin (which contains norethindrone acetate, not norgestimate) is not recommended for progesterone replacement therapy. For progesterone replacement, standard norgestimate dosing is 0.25 mg daily when used in combination with estrogen.

Clarification of Medication

It's important to first clarify that Lo Loestrin Fe is a combined oral contraceptive containing norethindrone acetate (a progestin) and ethinyl estradiol, not norgestimate. Norgestimate is a different progestin found in other contraceptive formulations.

Standard Norgestimate Dosing

According to the FDA drug label, norgestimate is typically available in a dose of 0.25 mg combined with 0.035 mg ethinyl estradiol 1. This is the standard dosage used in contraceptive formulations containing norgestimate.

Progesterone Replacement Considerations

For progesterone replacement therapy (rather than contraception):

• Norgestimate is not typically the first choice for progesterone replacement therapy
• When used for hormonal replacement, the standard dose remains 0.25 mg daily
• It must be combined with estrogen for proper endometrial protection

Better Options for Progesterone Replacement

For true progesterone replacement therapy, other options are preferred:

1. Micronized progesterone (first choice):

   • 200 mg orally daily for 12-14 days per month (sequential regimen)
   • Provides better cardiovascular safety profile 2

2. Medroxyprogesterone acetate:

   • 10 mg daily for 12-14 days per month (sequential regimen)
   • 2.5 mg daily (continuous regimen) 2

3. Dydrogesterone:

   • 10 mg for 12-14 days per month (sequential regimen)
   • 5 mg daily (continuous regimen) 2

Administration Considerations

• For sequential regimens: Progestin is added for 12-14 days every 28 days
• For continuous regimens: Progestin is taken daily without interruption
• The choice between sequential and continuous depends on whether withdrawal bleeding is desired or not 2

Monitoring and Safety

When using norgestimate or any progestin for replacement therapy:

• Monitor for breakthrough bleeding which may indicate need for dose adjustment
• Be aware of contraindications including history of thromboembolism, liver disease, undiagnosed vaginal bleeding, and breast cancer 1
• Consider potential drug interactions, particularly with medications that induce CYP3A4 enzymes, which may decrease effectiveness 1

Clinical Caution

Norgestimate has minimal androgenic activity compared to other progestins 3, which may be beneficial for lipid profiles. However, it undergoes metabolism to levonorgestrel in the body (approximately 22% of the dose) 4, which contributes to its pharmacological effects.

For true progesterone replacement therapy in conditions like premature ovarian insufficiency, micronized progesterone remains the safest and most physiologic option with the best cardiovascular risk profile.