Concurrent dosing of oxandrolone with warfarin may result in unexpectedly
large increases in the INR or prothrombin time (PT). When oxandrolone is prescribed
to patients being treated with warfarin, doses of warfarin may need to be decreased
significantly to maintain the desirable INR level and diminish the risk of potentially
serious bleeding (See PRECAUTIONS: DRUG INTERACTIONS).
Women should be observed for signs of virilization (deepening of the voice, hirsutism, acne, clitoromegaly). Discontinuation of drug therapy at the time of evidence of mild virilism is necessary to prevent irreversible virilization. Some virilizing changes in women are irreversible even after prompt discontinuance of therapy and are not prevented by concomitant use of estrogens. Menstrual irregularities may also occur.
Anabolic steroids may cause suppression of clotting factors II, V, VII, and X, and an increase in prothrombin time.
Oxandrin (oxandrolone) , at daily doses of 5 mg bid, and 10 mg bid, was evaluated in four
clinical trials involving a total of 339 patients with different underlying
medical conditions. The maximum duration of treatment was 4 months with the
average duration of treatment from 68.5 days to 94.7 days across the studies.
A total of 172 elderly patients ( ≥ 65 years of age) received Oxandrin (oxandrolone) treatment.
Mean weight gain was similar in those ≥ 65 and those < 65 years of age.
No significant differences in efficacy were detected between the 5 mg bid and
10 mg bid daily doses. The adverse event profiles were similar between the two
age groups although the elderly, particularly in women, had a greater sensitivity
to fluid retention and increases in hepatic transaminases. A single dose pharmacokinetic
study in elderly volunteers revealed an increased half-life when compared to
younger volunteers. (see CLINICAL PHARMACOLOGY) Based on greater sensitivity
to drug-induced fluid retention and transaminase elevations, a lower dose is
recommended in the elderly (see DOSAGE AND ADMINISTRATION).
Women with disseminated breast carcinoma should have frequent determination
of urine and serum calcium levels during the course of therapy. (See WARNINGS).
Because of the hepatotoxicity associated with the use of 17-alpha-alkylated androgens, liver function tests should be obtained periodically.
Periodic (every 6 months) x-ray examinations of bone age should be made during treatment of children to determine the rate of bone maturation and the effects of androgen therapy on the epiphyseal centers.
Androgenic anabolic steroids have been reported to increase low-density lipoproteins and decrease high-density lipoproteins. Therefore, caution is required when administering these agents to patients with a history of cardiovascular disease or who are at risk for cardiovascular disease. Serum determination of lipid levels should be performed periodically and therapy adjusted accordingly.
Hemoglobin and hematocrit should be checked periodically for polycythemia in patients who are receiving high doses of anabolic steroids.
Carcinogenesis, mutagenesis, impairment of fertility
Oxandrolone has not been tested in laboratory animals for carcinogenic or mutagenic effects. In 2-year chronic oral rat studies, a dose-related reduction of spermatogenesis and decreased organ weights (testes, prostate, seminal vesicles, ovaries, uterus, adrenals, and pituitary) were shown.
Liver cell tumors have been reported in patients receiving long-term therapy
with androgenic anabolic steroids in high doses (See WARNINGS). Withdrawal
of the drugs did not lead to regression of the tumors in all cases.
Geriatric patients treated with androgenic anabolic steroids may be at an increased risk for the development of prostatic hypertrophy and prostatic carcinoma.
Teratogenic effects-Pregnancy Category X (See CONTRAINDICATIONS).
It is not known whether anabolic steroids are excreted in human milk. Because of the potential of serious adverse reactions in nursing infants from oxandrolone, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Anabolic agents may accelerate epiphyseal maturation more rapidly than linear
growth in children and the effect may continue for 6 months after the drug has
been stopped. Therefore, therapy should be monitored by x-ray studies at 6-month
intervals in order to avoid the risk of compromising adult height. Androgenic
anabolic steroid therapy should be used very cautiously in children and only
by specialists who are aware of the effects on bone maturation (See WARNINGS).