Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004093 (asthenia)
 2,650 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of anastrozole, a new selective aromatase inhibitor, in treating hormone-responsive metastatic breast cancer is discussed. Treatment options for hormone-dependent breast cancer focus on interfering with the endocrine system in an attempt to modify the effects of estrogen. Tamoxifen is the drug of choice for primary endocrine therapy, but there is a need for agents with similar or greater efficacy and better tolerability. Anastrozole inhibits the conversion of androgens to estrogens by aromatase. Bioavailability studies have demonstrated almost complete absorption of anastrozole after oral administration. The drug's terminal half-life after multiple doses is 50 hours. Anastrozole is cleared principally by the liver. Clinical trials comparing anastrozole with megestrol acetate demonstrated no significant differences in clinical efficacy, although a follow-up study revealed a longer median overall survival rate in patients receiving anastrozole. The drug is well tolerated. Among the most frequently reported adverse effects are asthenia, hot flashes, headache, and back pain. The recommended dosage is 1 mg daily. The average wholesale cost of month's supply of anastrozole is $187.20, compared with approximately $100 for generic megestrol acetate or aminoglutethimide plus hydrocortisone. Although anastrozole will likely become the preferred second-line agent in the treatment of postmenopausal breast cancer in patients with disease progression after tamoxifen therapy, it is not a therapeutic alternative to aminoglutethimide on the basis of approved indications. Anastrozole and other aromatase inhibitors may have multiple applications in treating hormone-responsive breast cancer.
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PMID:Anastrozole: a selective aromatase inhibitor for the treatment of breast cancer. 952 27

Patients with hormone-sensitive breast cancer who have responded to tamoxifen may receive additional benefit from a second endocrine agent following progression or relapse after tamoxifen therapy. Fulvestrant (Faslodex((R)), ICI 182780, AstraZeneca Pharmaceuticals; Wilmington, Delaware) is a selective antagonist of estrogen designed to have no estrogenic effects. Lack of aqueous solubility led to the development of a parenteral formulation for monthly intramuscular administration. Fulvestrant has been shown to inhibit the proliferative effects of estrogen on sensitive tissues in vitro and in vivo, and is without apparent measurable estrogenic activity. The data upon which marketing approval for fulvestrant was based are summarized below. Eight hundred fifty-one postmenopausal women with advanced breast cancer were enrolled in two phase III studies, 400 in a North American double-blind study and 451 in a European open-label study, comparing the efficacy and safety of fulvestrant with anastrozole. Four hundred twenty-eight patients were randomized to receive fulvestrant 250 mg monthly by intramuscular injection and 423 patients were to receive anastrozole 1 mg daily. Patients were considered hormone sensitive either by receptor status or previous response to endocrine therapy. Over 96% of patients had previously received tamoxifen, either in the adjuvant setting or as treatment for metastatic disease. The primary study end points were response rate and time to progression. Response rates for patients treated with fulvestrant were 17% and 20% in the North American and European trials, respectively, compared with 17% and 15% in the anastrozole treatment arms. There were no statistically significant differences in response rates, time to progression, or survival between treatment arms in either study. The most common adverse events attributed to the treatment (>10%) were injection-site reactions and hot flashes. Common events (1%-10%) included asthenia, headache, and gastrointestinal disturbances (nausea, vomiting, and diarrhea), as well as rash and urinary tract infections. A small increase in joint disorders was reported in the anastrozole-treated patients. On April 25, 2002, fulvestrant 250 mg by monthly intramuscular injection was approved by the U.S. Food and Drug Administration for the treatment of hormone receptor-positive metastatic breast cancer in postmenopausal women with disease progression following antiestrogen therapy. Approval was based on similarity of response rates and time to progression between fulvestrant and anastrozole.
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PMID:FDA drug approval summaries: fulvestrant. 1249 Jul 35

Oral estrogens were the treatment of choice for carcinoma of the prostate for over four decades, but were abandoned because of an excess of cardiovascular and thromboembolic toxicity. It is now recognized that most of this toxicity is related to the first pass portal circulation, which upregulates the hepatic metabolism of hormones, lipids and coagulation proteins. Most of this toxicity can be avoided by parenteral (intramuscular or transdermal) estrogen administration, which avoids hepatic enzyme induction. It also seems that a short-term but modest increase in cardiovascular morbidity (but not mortality) is compensated for by a long-term cardioprotective benefit, which accrues progressively as vascular remodeling develops over time. Parenteral estrogen therapy has the advantage of giving protection against the effects of andropause (similar to the female menopause), which are induced by conventional androgen suppression and include osteoporotic fracture, hot flashes, asthenia and cognitive dysfunction. In addition, parenteral estrogen therapy is significantly cheaper than contemporary endocrine therapy, with substantive economic implications for health providers.
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PMID:Therapy Insight: parenteral estrogen treatment for prostate cancer--a new dawn for an old therapy. 1701 33