From the FDA Drug Label
Anabolic steroids suppress the gonadotropic functions of the pituitary and may exert a direct effect upon the testes During exogenous administration of anabolic androgens, endogenous testosterone release is inhibited through inhibition of pituitary luteinizing hormone (LH). The extent of testosterone suppression by Anavar (Oxandrolone) is not explicitly quantified in the drug label.
- The label states that endogenous testosterone release is inhibited through inhibition of pituitary luteinizing hormone (LH) during exogenous administration of anabolic androgens.
- It also mentions that spermatogenesis may be suppressed through feedback inhibition of pituitary follicle-stimulating hormone (FSH) at large doses. However, the label does not provide specific information on the degree of testosterone suppression caused by Oxandrolone 1.
From the Research
Testosterone Suppression by Anavar (Oxandrolone)
- The extent of testosterone suppression by Anavar (Oxandrolone) has been studied in several research papers 2, 3, 4, 5, 6.
- A study published in 1997 found that oxandrolone transiently suppressed the pituitary-testicular axis and altered GH pulsatility 2.
- Another study published in 2008 found that long-term receipt of oxandrolone was associated with low testosterone and SHBG levels, and erectile dysfunction 3.
- A study published in 1990 found that oxandrolone suppressed serum testosterone levels in male Sprague-Dawley rats 4.
- A study published in 1993 found that oxandrolone had androgenic effects, suppressing mean serum LH concentrations and serum testosterone concentrations in boys with constitutional delay of growth and puberty 5.
- A study published in 1994 found that oxandrolone induced a significant growth acceleration in boys with constitutional delay of growth and puberty, but did not affect the rate of development in secondary sexual characteristics 6.
Mechanism of Testosterone Suppression
- The mechanism of testosterone suppression by oxandrolone is not fully understood, but it is thought to be related to the drug's androgenic effects 5.
- Oxandrolone may decrease hepatic synthesis of SHBG, allowing exogenously supplied testosterone to be excreted 3.
- The drug may also alter GH pulsatility, which could affect testosterone production 2.
Clinical Implications
- The clinical implications of testosterone suppression by oxandrolone are significant, as it may affect the drug's efficacy and safety in certain patient populations 3, 5.
- Patients receiving oxandrolone should be monitored for signs of testosterone suppression, such as erectile dysfunction and low libido 3.
- The use of oxandrolone in patients with hypogonadism or other conditions affecting testosterone production should be carefully considered 5.