Vabon

Uses

Vabon is used for the following treatment-

• Endometriosis
• Benign breast disease
• Menorrhagia
• Gynecomastia
• Preoperative thinning of the endometrium before hysteroscopic endometrial ablation.

Vabon is also used to associated treatment for these conditions: Endometriosis, Fibrocystic Disease of Breast, Hereditary Angioedema, Refractory immune thrombocytopenia

How Vabon works

As a gonadotropin inhibitor, danazol suppresses the pituitary-ovarian axis possibly by inhibiting the output of pituitary gonadotropins. Vabon also depresses the preovulatory surge in output of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), thereby reducing ovarian estrogen production. Vabon may also directly inhibits ovarian steroidogenesis; bind to androgen, progesterone, and glucocorticoid receptors; bind to sex-hormone-binding globulin and corticosteroid-binding globulin; and increases the metabolic clearance rate of progesterone. Another mechanism of action by which danazol may use to facilitate regression of endometriosis is by decreasing IgG, IgM, and IgA concentrations, as well as phospholipid and IgG isotope autoantibodies. In the treatment of endometriosis, as a consequence of suppression of ovarian function, danazol causes both normal and ectopic endometrial tissues to become inactive and atrophic. This leads to anovulation and associated amenorrhea. In fibrocystic breast disease, the exact mechanism of action of danazol is unknown, but may be related to suppressed estrogenic stimulation as a result of decreased ovarian production of estrogen. A direct effect on steroid receptor sites in breast tissue is also possible. This leads to a disappearance of nodularity, relief of pain and tenderness, and possibly changes in the menstrual pattern. In terms of hereditary angioedema, danazol corrects the underlying biochemical deficiency by increasing serum concentrations of the deficient C1 esterase inhibitor, resulting in increased serum concentrations of the C4 component of the complement system. (Source: PharmGKB)

Dosage

Vabon dosage

Preoperative thinning of the endometrium:

• Adult: 400-800 mg daily, in up to 4 divided doses for 3-6 week.

Benign breast disorders:

• Adult: Initially, 100-400 mg daily in 2 divided doses adjusted according to response and continued for 3-6 month.

Hereditary angioedema:

• Adult: Initially, 200 mg bid-tid reduced thereafter according to patient's response.

Endometriosis:

• Adult: 200-800 mg daily in 2 divided doses adjusted according to response, for 3-6 month or if necessary, up to 9 month.

Menorrhagia:

• Adult: 200 mg once daily. Review treatment 3 month later.

Gynaecomastia:

• Adult: Male adolescents: Initially, 200 mg daily, may increase to 400 mg daily after 2 month if no response occurs; adult men: Initial: 400 mg daily in up to 4 divided doses. Usual treatment duration: 6 month.
• Child: Male adolescents: Initially, 200 mg daily increased to 400 mg after 2 month if no response occurs. Treatment usually up to 6 months.

Side Effects

Oedema, weight gain, sweating, acne, hirsutism, flushing, oily skin or hair, deepening of the voice, clitoral hypertrophy, amenorrhoea, hepatic dysfunction, CNS or GI disturbances, benign intracranial hypertension, reduction in breast size, visual disturbances, elevated LFT values.

Precaution

Epilepsy, migraine; cardiac, hepatic, renal disorders. Severe hypertension, diabetes, polycythaemia, history of thrombosis; children.

Interaction

Insulin: Patients taking danazol may show increased insulin resistance. The significance of this is not known but such patients should be carefully monitored.

Estrogens and progestogens: Theoretically danazol may interact with exogenous estrogens and/or progestogens. It has been suggested that danazol acts by binding to estrogen, progesterone or androgen receptors at various levels in the hypothalamic pituitary-ovarian axis. Therefore, women of child bearing age should use effective, non hormonal methods of contraception.

Anticonvulsant therapy: Vabon may affect the plasma concentration of carbamazepin and possibly the patient's response to this agent and to phenytoin. A similar interaction is possible for phenobarbital.

Antihypertensive therapy: Vabon can oppose the action of antihypertensive agents, possibly through effects on fluid retention.

Cyclosporine: Vabon can increase the plasma concentration of cyclosporine.

Migraine therapy: Vabon itself may provoke migraine and it may possibly reduce the effectiveness of medication to prevent the condition.

Food Interaction

• Take with or without food. The absorption is unaffected by food.

Vabon Hypertension interaction

[Major] Vabon possess androgenic activity that can result in salt and water retention.

Vabon is eliminated by the kidney, and its use is contraindicated in patients with severe renal dysfunction.

It should also be administered cautiously in patients adversely affected by volume overload, such as patients suffering from epilepsy, diabetes mellitus, migraine, cardiac or renal dysfunction, polycythemia and hypertension.

These patients will require careful observation.

Vabon Drug Interaction

Moderate: zolpidem, zolpidemUnknown: duloxetine, duloxetine, glucose, glucose, diltiazem, diltiazem, metoprolol, metoprolol, acetaminophen, acetaminophen, cyanocobalamin, cyanocobalamin, ascorbic acid, ascorbic acid, cholecalciferol, cholecalciferol, cetirizine, cetirizine

Vabon Disease Interaction

Major: abnormal uterine bleeding, androgen dependent tumors, hepatic dysfunction, impaired cardiac function, intracranial hypertension, porphyria, thromboembolic disease, volume overload/renal impairment

Half Life

Approximately 24 hours.

Pregnancy & Breastfeeding use

Category X: Studies in animals or human beings have demonstrated fetal abnormalities or there is evidence of fetal risk based on human experience or both, and the risk of the use of the drug in pregnant women clearly outweighs any possible benefit. The drug is contraindicated in women who are or may become pregnant.

Contraindication

• Pregnancy and breast-feeding
• Impaired hepatic, renal, or cardiac function
• Porphyria
• Thromboembolic disease
• Androgen-dependent tumor
• Abnormal vaginal bleeding that has not been fully investigated.
• Hypersensitivity to danazol.

Acute Overdose

There have been no incidents of acute overdosage with Vabon and it is unlikely that any immediate serious reaction will be seen from a single excessive dose. In case of the acute overdosage, the drug should be removed by gastric lavage and the patient should be kept under observation.

Storage Condition

Store at 15-30°C.

Innovators Monograph

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