Danazol (Page 2 of 3)
Single dose administration of 100 mg and 200 mg capsules of danazol to female volunteers showed that both the extent of availability and the maximum plasma concentration increased by 3 to 4 fold, respectively, following a meal (> 30 grams of fat), when compared to the fasted state. Further, food also delayed mean time to peak concentration of danazol by about 30 minutes. Even after multiple dosing under less extreme food/fasting conditions, there remained approximately a 2 to 2.5 fold difference in bioavailability between the fed and fasted states.
Danazol is lipophilic and can partition into cell membranes, indicating the likelihood of distribution into deep tissue compartments.
Metabolism and Excretion
Danazol appears to be metabolized and the metabolites are eliminated by renal and fecal pathways. The two primary metabolites excreted in the urine are 2-hydroxymethyl danazol and ethisterone. At least ten different products were identified in feces.
The reported elimination half-life of danazol is variable across studies. The mean half-life of danazol in healthy males is 9.7 h. After 6 months of 200 mg three times a day dosing in endometriosis patients, the half-life of danazol was reported as 23.7 hours.
INDICATIONS AND USAGE
Danazol capsules are indicated for the treatment of endometriosis amenable to hormonal management.
Danazol capsules are indicated for the prevention of attacks of angioedema of all types (cutaneous, abdominal, laryngeal) in males and females.
Danazol should not be administered to patients with:
- Undiagnosed abnormal genital bleeding.
- Markedly impaired hepatic, renal, or cardiac function.
- Pregnancy. (See WARNINGS.)
- Porphyria — Danazol can induce ALA synthetase activity and hence porphyrin metabolism.
- Androgen-dependent tumor.
- Active thrombosis or thromboembolic disease and history of such events.
- Hypersensitivity to danazol.
Use of danazol in pregnancy is contraindicated. A sensitive test (e.g., beta subunit test if available) capable of determining early pregnancy is recommended immediately prior to start of therapy. Additionally a non-hormonal method of contraception should be used during therapy. If a patient becomes pregnant while taking danazol, administration of the drug should be discontinued and the patient should be apprised of the potential risk to the fetus. Exposure to danazol in utero may result in androgenic effects on the female fetus; reports of clitoral hypertrophy, labial fusion, urogenital sinus defect, vaginal atresia, and ambiguous genitalia have been received (see PRECAUTIONS, Pregnancy, Teratogenic Effects ).
Thromboembolism, thrombotic and thrombophlebitic events including sagittal sinus thrombosis and life-threatening or fatal strokes have been reported.
Experience with long-term therapy with danazol is limited. Peliosis hepatis and benign hepatic adenoma have been observed with long-term use. Peliosis hepatis and hepatic adenoma may be silent until complicated by acute, potentially life-threatening intraabdominal hemorrhage. The physician therefore should be alert to this possibility. Attempts should be made to determine the lowest dose that will provide adequate protection. If the drug was begun at a time of exacerbation of hereditary angioneurotic edema due to trauma, stress or other cause, periodic attempts to decrease or withdraw therapy should be considered.
Danazol has been associated with several cases of benign intracranial hypertension also known as pseudotumor cerebri. Early signs and symptoms of benign intracranial hypertension include papilledema, headache, nausea and vomiting, and visual disturbances. Patients with these symptoms should be screened for papilledema and, if present, the patients should be advised to discontinue danazol immediately and be referred to a neurologist for further diagnosis and care.
A temporary alteration of lipoproteins in the form of decreased high density lipoproteins and possibly increased low density lipoproteins has been reported during danazol therapy. These alterations may be marked, and prescribers should consider the potential impact on the risk of atherosclerosis and coronary artery disease in accordance with the potential benefit of the therapy to the patient.
Patients should be watched closely for signs of androgenic effects some of which may not be reversible even when drug administration is stopped.
Because danazol may cause some degree of fluid retention, conditions that might be influenced by this factor, such as epilepsy, migraine, or cardiac or renal dysfunction, polycythemia and hypertension require careful observation. Use with caution in patients with diabetes mellitus.
Since hepatic dysfunction manifested by modest increases in serum transaminases levels has been reported in patients treated with danazol, periodic liver function tests should be performed (see WARNINGS and ADVERSE REACTIONS).
Administration of danazol has been reported to cause exacerbation of the manifestations of acute intermittent porphyria (see CONTRAINDICATIONS).
Laboratory monitoring of the hematologic state should be considered.
Prolongation of prothrombin time occurs in patients stabilized on warfarin.
Therapy with danazol may cause an increase in carbamazepine levels in patients taking both drugs.
Danazol can cause insulin resistance. Caution should be exercised when used with antidiabetic drugs.
Danazol may raise the plasma levels of cyclosporin and tacrolimus, leading to an increase of the renal toxicity of these drugs. Monitoring of systemic concentrations of these drugs and appropriate dose adjustments may be needed when used concomitantly with danazol.
Danazol can increase the calcemic response to synthetic vitamin D analogs in primary hypoparathyroidism.
The risk of myopathy and rhabdomyolysis is increased by concomitant administration of danazol with statins such as simvastatin, atorvastatin and lovastatin. Caution should be exercised if used concomitantly. Consult the product labeling for statin drugs for specific information on dose restrictions in presence of danazol.
Danazol treatment may interfere with laboratory determinations of testosterone, androstenedione and dehydroepiandrosterone. Other metabolic events include a reduction in thyroid binding globulin and T4 with increased uptake of T3, but without disturbance of thyroid stimulating hormone or of free thyroxin index.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Current data are insufficient to assess the carcinogenicity of danazol.
Danazol administered orally to pregnant rats from the 6th through the 15th day of gestation at doses up to 250 mg/kg/day (7 to 15 times the human dose) did not result in drug-induced embryotoxicity or teratogenicity, nor difference in litter size, viability or weight of offspring compared to controls. In rabbits, the administration of danazol on days 6 to 18 of gestation at doses of 60 mg/kg/day and above (2 to 4 times the human dose) resulted in inhibition of fetal development.
Safety and effectiveness in pediatric patients have not been established.
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