HALOTESTIN Tablets contain fluoxymesterone, an androgenic hormone.
Fluoxymesterone is a white or nearly white, odorless, crystalline powder, melting at or about 240° C, with some decomposition. It is practically insoluble in water, sparingly soluble in alcohol, and slightly soluble in chloroform.
The chemical name for fluoxymesterone is androst-4-en-3-one, 9-fluoro-11,17-dihydroxy-17-methyl-, (11β,17β)-. The molecular formula is C20H29FO3 and the molecular weight 336.45.
The structural formula is represented below:
Each HALOTESTIN tablet, for oral administration, contains 2 mg, 5 mg or 10 mg fluoxymesterone. Inactive ingredients: calcium stearate, corn starch, FD&C Yellow No. 5, lactose, sorbic acid, sucrose, tragacanth. In addition, the 2 mg tablet contains FD&C Yellow No. 6 and the 5 mg and 10 mg contain FD&C Blue No. 2.
Endogenous androgens are responsible for normal growth and development of the male sex organs and for maintenance of secondary sex characteristics. These effects include growth and maturation of the prostate, seminal vesicles, penis, and scrotum; development of male hair distribution, such as beard, pubic, chest, and axillary hair; laryngeal enlargement, vocal cord thickening, and alterations in body musculature and fat distribution. Drugs in this class also cause retention of nitrogen, sodium, potassium, and phosphorus, and decreased urinary excretion of calcium. Androgens have been reported to increase protein anabolism and decrease protein catabolism. Nitrogen balance is improved only when there is sufficient intake of calories and protein.
Androgens are responsible for the growth spurt of adolescence and for eventual termination of linear growth, brought about by fusion of the epiphyseal growth centers. In children, exogenous androgens accelerate linear growth rates, but may cause disproportionate advancement in bone maturation. Use over long periods may result in fusion of the epiphyseal growth centers and termination of the growth process. Androgens have been reported to stimulate production of red blood cells by enhancing production of erythropoietic stimulation factor.
During exogenous administration of androgens, endogenous testosterone release is inhibited through feedback inhibition of pituitary luteinizing hormone (LH). At large doses of exogenous androgens, spermatogenesis may also be suppressed through feedback inhibition of pituitary follicle stimulating hormone (FSH).
Inactivation of testosterone occurs primarily in the liver.
The half-life of fluoxymesterone after oral administration is approximately 9.2 hours.