Generic Name
Micronised progesterone
Brand Names
Utrogestan
Prometrium
Yamin
Progeffik
Micronor (not to be confused—Micronor is norethisterone in some regions)
Drug Class
Natural progestogen
Micronised progesterone hormone
Steroid hormone
Luteal phase support agent
Selective progesterone receptor agonist
Mechanism of Action
Utrogestan contains micronised progesterone, a bioidentical hormone chemically identical to endogenous human progesterone
Binds to nuclear progesterone receptors (PR-A and PR-B) in target tissues including endometrium, cervix, vagina, breast, and hypothalamus
Exerts progestogenic activity by
Transforming a proliferative endometrium into a secretory one
Stabilizing the endometrium to prevent estrogen-induced hyperplasia
Reducing gonadotropin (LH and FSH) release from the pituitary
Regulating immune tolerance and promoting embryo implantation in reproductive contexts
Inhibiting uterine contractility to support pregnancy
No androgenic, estrogenic, or glucocorticoid activity
Indications
Menopausal Hormone Replacement Therapy (HRT)
Used with estrogen therapy to protect endometrium in non-hysterectomized women
Cyclic or continuous use depending on regimen
Luteal Phase Support
Used in assisted reproductive technology ART
IVF or ICSI cycles to support implantation and early pregnancy
Progesterone Deficiency
Secondary amenorrhea
Irregular menstrual cycles
Luteal insufficiency
Threatened or Recurrent Miscarriage
Due to luteal phase defect or low endogenous progesterone
Prevention of Preterm Birth
Used vaginally in women with a short cervix or history of preterm labor
Off-Label Uses
Premenstrual syndrome (PMS)
Endometrial hyperplasia prevention
Infertility due to luteal insufficiency
Dosage and Administration
Oral Administration
Common dose 200 mg daily
For HRT
200 mg orally at bedtime for 12 days per 28-day cycle with estrogen
For luteal phase or amenorrhea
200–300 mg daily for 10–12 days in second half of cycle
Vaginal Administration
100–400 mg daily depending on indication
Used in ART for luteal support
200 mg two or three times daily starting after embryo transfer and continued until pregnancy test or longer if pregnant
Used in prevention of preterm birth
100 mg vaginal capsule at bedtime from 16–36 weeks in eligible women
Rectal Use
Not common but used off-label in some countries
Especially where vaginal route is not acceptable
Treatment Duration
Depends on indication
Short cycles for amenorrhea or luteal support
Long-term cyclic administration for HRT
Extended support during first trimester in IVF
Pharmacokinetics
Micronisation enhances oral bioavailability
Absorption is rapid but variable when taken orally
Undergoes first-pass hepatic metabolism
Peak plasma levels in 1–3 hours
Oral half-life is approximately 5–20 hours
Vaginal route bypasses liver and achieves high local uterine concentrations
Progesterone is metabolized in the liver to pregnanediol and other inactive metabolites
Excreted primarily in urine as glucuronide conjugates
Contraindications
Known hypersensitivity to progesterone or excipients (including peanut oil in some oral forms)
Undiagnosed abnormal vaginal bleeding
Known or suspected breast or genital hormone-sensitive malignancy
Active or past history of venous thromboembolism
Severe hepatic dysfunction or liver disease
Missed abortion or ectopic pregnancy
Porphyria
Warnings and Precautions
Use with caution in women with cardiovascular disease or thrombotic risk
Monitor for signs of depression in susceptible patients
May cause drowsiness or dizziness especially with oral dosing
Not a contraceptive when used alone
Check for pregnancy before starting therapy if applicable
Avoid in patients with peanut allergy (certain oral formulations contain peanut oil)
Vaginal use preferred in ART due to local endometrial action and better tolerability
In long-term use for HRT monitor breast and endometrial status regularly
Use the lowest effective dose for the shortest duration
Adverse Effects
Oral Route
Somnolence
Dizziness
Bloating
Breast tenderness
Headache
Mood changes
Nausea
Vaginal Route
Vaginal irritation
Discharge
Local discomfort
Less systemic side effects than oral route
Rare or Serious Effects
Thromboembolic events
Cholestatic jaundice
Skin rashes
Allergic reactions
Breakthrough bleeding
Overdose
Symptoms
Sedation
Nausea
Vomiting
Dizziness
Breast discomfort
Treatment is supportive
No specific antidote
Activated charcoal if ingestion is recent and symptomatic
Drug Interactions
CYP3A4 inducers like rifampin, carbamazepine, phenytoin may reduce progesterone levels
Ketoconazole and other inhibitors may increase serum levels
Interactions with estrogen in HRT regimens can alter bleeding patterns
May enhance sedative effects of CNS depressants
Caution with anticoagulants due to potential hormonal effect on coagulation
Use in Special Populations
Pregnancy
Generally safe when used for luteal support or miscarriage prevention
FDA category B
Prescribed in early pregnancy to support implantation
Lactation
Excreted in breast milk
Generally considered safe
Used in postpartum settings with caution
Pediatrics
Not indicated
Geriatrics
Used in HRT in postmenopausal women
Monitor for cardiovascular and breast-related events
Hepatic Impairment
Use is contraindicated in severe liver dysfunction
Monitoring Parameters
Menstrual pattern regularity
Bleeding profile
Liver function if long-term oral use
Signs of thromboembolic events
Serum progesterone levels in fertility protocols
Endometrial status during long-term HRT
Comparative Pharmacology
Compared to synthetic progestins
Micronised progesterone is bioidentical and better tolerated
Lower risk of breast cancer and thrombotic events than medroxyprogesterone acetate in observational data
Less androgenic and does not worsen lipid profile
Does not reduce beneficial HDL cholesterol as many synthetic progestins do
Less likely to cause mood disturbance compared to norethisterone
Compared to dydrogesterone
Both are orally active
Micronised progesterone has broader use in fertility protocols and HRT
Micronised form often preferred for bioidentical HRT
Formulations Available
Capsules 100 mg and 200 mg for oral or vaginal use
Vaginal tablets and gels in ART
Oral micronised progesterone in oil-based or soft gel capsule form
Available as generic and branded products globally
Regulatory and Legal Status
Prescription-only medicine
Approved by EMA and FDA
Included in HRT regimens in NICE and EMAS guidelines
Not a controlled substance
Widely used in fertility centers and menopause management clinics
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