Usage
Allylestrenol is a synthetic progestogen, structurally similar to progesterone. It is primarily prescribed to prevent miscarriage (both threatened and recurrent) and premature labor in pregnant women with progesterone deficiency. Although traditionally used for these purposes, recent evidence suggests limited efficacy in preventing miscarriage unless progesterone deficiency is established.
Pharmacological Classification: Progestogen, Steroid hormone.
Mechanism of Action: Allylestrenol binds to progesterone receptors, mimicking the effects of natural progesterone. It supports pregnancy by promoting placental function, stimulating the production of placental hormones (e.g., progesterone, estriol, hCG), and reducing uterine contractility via β2-adrenergic receptor stimulation.
Alternate Names
While “Allylestrenol” is the generic name, it is marketed under various brand names internationally, such as: Arandal, Aroserine, Cobarenol, Elmolan, Gravynon, Maintane Tab, Perselin, Pregnolin, and Turinal. Brand names in India include Noteron, Ecogest, Menor-N, Corolut-N, Prevent N, Uflox (400 mg), Sofnin, Foegard, Regestrone, and Rensure.
How It Works
Pharmacodynamics: Allylestrenol primarily acts on the uterus, placenta, and potentially the hypothalamus and pituitary gland. It exerts its therapeutic effect by binding to progesterone receptors. This leads to the following effects crucial for maintaining pregnancy:
- Transformation of the endometrium: Prepares the uterine lining for implantation and supports the developing fetus.
- Placental development and function: Stimulates placental hormone production, promoting fetal growth and development.
- Reduction of uterine contractility: Relaxes the uterine muscles, preventing premature labor.
Pharmacokinetics: Limited information is available on allylestrenol’s pharmacokinetic profile.
- Absorption: Assumed to be absorbed orally.
- Metabolism: Likely metabolized in the liver.
- Elimination: The exact pathways are unclear, but it’s believed to be excreted as metabolites through urine and bile, potentially involving enterohepatic recirculation.
Receptor Binding: Allylestrenol binds to progesterone receptors. It has little estrogenic or androgenic activity, distinguishing it from some other progestogens.
Enzyme Inhibition/Neurotransmitter Modulation: No specific enzyme inhibition or neurotransmitter modulation is documented for allylestrenol.
Dosage
Dosage guidelines vary according to the specific condition being addressed:
Standard Dosage
Adults:
- Threatened Miscarriage (progesterone deficiency): 5 mg three times daily for 5-7 days. Treatment can be prolonged if necessary, with gradual dose reduction if symptoms improve.
- Recurrent Miscarriage: 5-10 mg daily, starting as soon as pregnancy is confirmed and continuing for at least one month after the critical period.
- Premature Labor: Dosage individualized, up to a maximum of 40 mg daily.
Children: Not recommended for children under 16 years of age.
Special Cases:
- Elderly Patients: No specific dosage recommendations; exercise caution due to potential age-related decline in organ function.
- Patients with Renal Impairment: Use with caution; dose adjustments may be necessary.
- Patients with Hepatic Dysfunction: Contraindicated in severe hepatic impairment.
- Patients with Comorbid Conditions: Use with caution in patients with heart disease, epilepsy, migraine, asthma, diabetes, and renal dysfunction. Close monitoring is essential.
Clinical Use Cases
Allylestrenol is not typically employed in the clinical settings mentioned (intubation, surgical procedures, mechanical ventilation, ICU use, emergency situations). Its use is primarily confined to pregnancy-related conditions as outlined above.
Dosage Adjustments
Dosage adjustments are generally made based on patient response and tolerance. Dose reductions are often implemented if symptoms improve.
Side Effects
Common Side Effects:
- Nausea
- Vomiting
- Headache
- Breast tenderness
- Bloating
- Fluid retention (edema)
- Changes in libido
- Menstrual irregularities
Rare but Serious Side Effects:
- Blood clots (thromboembolic events)
- Liver dysfunction (jaundice)
- Allergic reactions
- Visual disturbances (blurred vision, diplopia)
- Severe headache
- Mood changes
Long-Term Effects:
Limited data available; potential for unknown long-term effects.
Adverse Drug Reactions (ADR):
Allergic reactions, blood clots, and liver dysfunction are serious ADRs requiring prompt medical attention.
Contraindications
- Hypersensitivity to allylestrenol
- History of thromboembolic disorders
- Severe liver disease (hepatic impairment)
- Undiagnosed vaginal bleeding
- Incomplete abortion
- Hormone-dependent cancers (breast cancer, endometrial cancer)
Drug Interactions
Allylestrenol may interact with:
- Enzyme-inducing drugs: Anticonvulsants (phenytoin, carbamazepine, phenobarbital, primidone), antifungals (griseofulvin, ketoconazole, itraconazole, posaconazole), and rifampicin. These can decrease allylestrenol levels.
- Enzyme-inhibiting drugs: May increase allylestrenol levels.
- Anticoagulants (warfarin): Effects may be altered; close monitoring required.
- Corticosteroids and immunosuppressants: May affect allylestrenol metabolism.
- Herbal supplements (St. John’s Wort): May reduce allylestrenol effectiveness.
- Alcohol and grapefruit: Potential interactions; caution advised.
Pregnancy and Breastfeeding
Allylestrenol is generally considered safe during pregnancy for its intended use in managing progesterone deficiency-related pregnancy complications. However, it’s not recommended during breastfeeding as it may be excreted in breast milk and potentially affect the infant.
Drug Profile Summary
- Mechanism of Action: Binds to progesterone receptors, supporting pregnancy maintenance.
- Side Effects: Nausea, headache, bloating, breast tenderness, fluid retention; rarely, blood clots, liver dysfunction.
- Contraindications: Thromboembolic disorders, hepatic impairment, hormone-dependent cancers, undiagnosed vaginal bleeding.
- Drug Interactions: Enzyme inducers/inhibitors, anticoagulants, certain herbal supplements.
- Pregnancy & Breastfeeding: Generally safe during pregnancy for specific conditions; not recommended during breastfeeding.
- Dosage: Varies based on the condition; refer to detailed dosage section above.
- Monitoring Parameters: Fetal growth and development, uterine activity, signs of liver dysfunction, blood clotting parameters.
Popular Combinations
Limited information available on regularly used drug combinations with allylestrenol.
Precautions
- Pre-existing conditions (heart disease, epilepsy, migraine, asthma, renal dysfunction, diabetes): Use with caution.
- Pregnant Women: For specific indications under medical supervision; discontinue after delivery.
- Breastfeeding Mothers: Avoid due to potential for neonatal exposure.
- Children & Elderly: Not recommended for children under 16; use with caution in the elderly.
- Lifestyle Considerations: Advise patients against alcohol and smoking. Assess driving ability as it might induce dizziness/drowsiness.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Allylestrenol?
A: The dosage varies depending on the specific indication. Please refer to the detailed dosage section above for specific recommendations for threatened miscarriage, recurrent miscarriage, and premature labor.
Q2: Is Allylestrenol safe during pregnancy?
A: Generally considered safe for specific indications related to progesterone deficiency, under the supervision of a healthcare professional. It is not recommended for general pregnancy maintenance in the absence of progesterone deficiency.
Q3: Can I take Allylestrenol while breastfeeding?
A: Allylestrenol is not recommended during breastfeeding as it may pass into breast milk and affect the infant.
Q4: What are the common side effects of Allylestrenol?
A: Common side effects include nausea, vomiting, headache, breast tenderness, bloating, fluid retention, changes in libido, and menstrual irregularities.
Q5: What are the serious side effects of Allylestrenol?
A: Serious side effects, though rare, include thromboembolic events (blood clots), liver dysfunction (jaundice), allergic reactions, and visual disturbances.
Q6: Who should not take Allylestrenol?
A: Allylestrenol is contraindicated in individuals with hypersensitivity to the drug, history of thromboembolic disorders, severe liver disease, undiagnosed vaginal bleeding, incomplete abortion, and hormone-dependent cancers.
Q7: Does Allylestrenol interact with other medications?
A: Yes, allylestrenol may interact with certain medications, including enzyme-inducing drugs (anticonvulsants, antifungals), enzyme-inhibiting drugs, anticoagulants, corticosteroids, immunosuppressants, some herbal supplements (St. John’s Wort), alcohol, and grapefruit juice. Consult with a healthcare provider regarding potential drug interactions.
Q8: How does Allylestrenol work to prevent miscarriage?
A: Allylestrenol works by mimicking the actions of progesterone, a hormone crucial for maintaining pregnancy. It helps stabilize the uterine lining, supports placental function, and prevents uterine contractions. It’s important to note that its efficacy in preventing miscarriage is primarily seen in cases of proven progesterone deficiency.
Q9: What should I do if I miss a dose of Allylestrenol?
A: Take the missed dose as soon as you remember. However, if it’s almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not double the dose to catch up.
Q10: Are there any long-term effects of using Allylestrenol?
A: Limited data are available on the long-term effects of allylestrenol use. It’s always crucial to discuss the benefits and risks with your healthcare provider before starting or continuing treatment.
