EXLUTON

Indications

• Hormonal contraception
• Menstrual disorders
• Endometrial protection in hormone replacement therapy

Dosage

Children: Refer to BNF for Children for appropriate dosing information.

Adults: 0.5 mg to 1 mg taken orally, once daily.

Mechanism of action

Lynestrenol enhances the stimulation of normal human lymphocytes, increasing the phytohemagglutinin response and mixed-lymphocyte cultures. This modulation may affect T cell functions in vitro. Additionally, it induces changes in the endometrium that inhibit the implantation of a blastocyst, making nidation impossible.

Pharmacodynamics

Lynestrenol exerts its effects primarily through progesterone receptor binding, leading to changes in the endometrium and cervical mucus. It promotes secretory changes in the endometrium, inhibits ovulation, and increases the viscosity of cervical mucus, thereby preventing sperm passage. Its immunomodulatory effects on lymphocytes suggest a potential role in influencing immune responses.

Pharmacokinetics

Lynestrenol is rapidly absorbed after oral administration, with peak plasma concentrations typically occurring within a few hours. It has a high bioavailability due to its low first-pass metabolism. The drug is metabolized in the liver and excreted mainly in urine. The elimination half-life is approximately 10 to 20 hours.

Contra-indications

• Pregnancy
• Known or suspected hormone-sensitive malignancies
• Undiagnosed vaginal bleeding
• Severe liver disease
• Thromboembolic disorders

Adverse effects

• Nausea
• Headache
• Breast tenderness
• Mood changes
• Weight gain
• Fatigue
• Acne

Interactions

• Rifampicin may decrease the effectiveness of lynestrenol
• Anticonvulsants (such as phenytoin) may reduce its effectiveness
• St. John's Wort may reduce plasma concentrations of lynestrenol

Precautions

• Monitor for signs of thromboembolic events
• Use with caution in patients with a history of depression
• Consider alternative contraceptive methods in patients with severe liver disease

Pregnancy

Lynestrenol is contraindicated in pregnancy due to the risk of adverse effects on the fetus.

Breast-feeding

Lynestrenol is excreted in breast milk; caution is advised when administering to nursing mothers.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Formulations

• Tablets: 0.5 mg

Mechanism of action

Lynestrenol, a synthetic steroid progesterone-like substance, has been found to enhance the stimulation of normal human lymphocytes. It increases the phytohemagglutinin response and the mixed-lymphocyte cultures. This augmentation can, in some cases, be higher than 100% of the phytohemagglutinin or mixed lymphocyte reaction baseline. There is no significant effect on the pokeweed mitogen stimulation. It is concluded that lynestrenol can modulate, "in vitro", some T cell functions. In 10 women taking 0.5 mg lynestrenol for oral contraception endometrium biopsies were carried out in several consecutive cycles between the 21st and 25th day of each cycle. In addition pregnandiol excretion in the urine was measured in one of the last three treatment cycles always on the 10th and 21st day of cycle. During treatment of a characteristic, monomorphic microscopical endometrium picture was observed with hardly distinct endometrium glands and only slight decidualike transformation of cellular elements of the stroma. From these histological pictures it is concluded that oral application of 0,5 mg lynestrenol produces endometrium changes characterized by insufficient transformation so that nidation of a blastocyte becomes impossible.