Product Name: Arimidex
Chemical Name: Anastrozole
Manufacturer: Dragon Pharma
Presentation: 100 x 1mg
Arimidex by Dragon Pharma AKA Anastrozole was first marketed under the trade name Arimidex by Astra Zeneca. Arimidex is a non-steroidal aromatase-inhibiting drug approved for treatment of breast cancer after surgery, as well as for metastasis in both pre and post-menopausal women. The severity of breast cancer is increased by estrogen, as sex hormones cause hyperplasia, and differentiation at estrogen receptor sites. Arimidex works by inhibiting the synthesis of estrogen. The patent on Arimidex by Astra Zeneca expired June 2010.
The ATAC (Arimidex, Tamoxifen, Alone or in Combination) trial was an international randomised controlled trial of 9366 women with localized breast cancer who received either Anastrozole,Tamoxifen, or both for five years, followed by five years of follow-up. After more than 5 years the group that received Dragon Pharma Arimidex had significantly better clinical results than the Tamoxifen group. The trial suggested that Anastrozole is the preferred medical therapy for post-menopausal women with localized breast cancer, which is estrogen receptor (ER) positive. Another study found that the risk of recurrence was reduced 40%, but was associated with an increased risk of bone fractures. The study concluded that ER positive patients benefited from switching from Tamoxifen to Arimidex in patients who have completed 2 years’ of Tamoxifen.
Mechanism of action: Anastrozole binds reversibly to the aromatase enzyme through competitive inhibition, inhibits the conversion of androgens to estrogens in peripheral tissues (outside the CNS), and a few CNS sites in various regions within the brain.
Side effects: Bone weakness has been associated with Anastrozole. Women who switched to Anastrozole after two years on Tamoxifen reported twice as many fractures as those who continued to take Tamoxifen (2.1% compared to 1%). Bisphosphonates are sometimes prescribed to prevent the osteoporosis induced by aromatase inhibitors. The level of circulating estradiol is likely causal here and not the Anastrozole itself, and so the dose will determine likelihood of osteoporosis (estradiol inhibits osteoclasts, which resorb bone).
Usage in men: Arimidex has been tested for reducing estrogens, including estradiol, in men. Excess estradiol in men can cause benign prostatic hyperplasia, gynecomastia, and symptoms of hypogonadism. It can also contribute to increased risk of stroke, heart attack, chronic inflammation, prostate enlargement and prostate cancer. Some athletes and body builders use Anastrozole as part of their steroid cycle to reduce and prevent symptoms of excess estrogen–gynecomastia, emotional lability and water retention. Study data suggests dosages of 0.5 mg to 1 mg a day reduce serum estradiol approx. 50% in men, which differs in post-menopausal women.