Megestrol acetate

Metabolism of progestogens used for contraception and menopausal hormone therapy

A variety of progestogens are widely used by women for contraception and menopausal hormone therapy. The progestogens undergo extensive metabolism by oral and parenteral routes of administration to form many metabolites. Although a small number of metabolites have been shown to be biologically active, most have not been tested for biologic activity. The present review shows that we know most about progesterone metabolism, followed by the metabolism of levonorgestrel and norethindrone. Very few studies have been carried out on metabolism of most of the progestogens. The clinical significance of this deficiency is that those progestogen metabolites that bind to the progesterone receptors may also bind to other steroid receptors and be responsible for some of the well-documented side effects of administered progestogens. We also discuss how obesity and genetic polymorphisms alter progestogen metabolism, and how development of oral progestogen formulations that are targeted to the colon, where the concentration of steroid-metabolizing enzymes is much lower than in the proximal gut, may have a beneficial effect on progestogen metabolism.

Controversies Involving the Systemic Treatment for Metastatic Prostatic Cancer

In the United States, 1987 estimates of cancer incidence by site indicate that prostatic cancer is equal to lung cancer as the first in incidence in adult males. Over 90,000 new cases are diagnosed and between 25-30,000 patients die of this disease each year. While early prostatic cancer is a surgically curable disease, the majority of patients present with widely metastatic cancer, where the main objective of treatment is palliation.

Naturally occurring, natural product inspired and synthetic heterocyclic anti-cancer drugs

This chapter describes the importance and activity of a huge number of commercially available naturally occurring, natural product derived or synthetic heterocyclic anti-cancer drugs.

Pluronic block copolymers and Pluronic poly(acrylic acid) microgels in oral delivery of megestrol acetate

Several Pluronic-based formulations were studied in-vitro and in a rat model with respect to the release and bioavailability of megestrol acetate (MA) after oral administration. It was demonstrated that an aqueous, micellar formulation comprising a mixture of a hydrophobic (L61) and a hydrophilic (F127) Pluronic copolymer, significantly enhanced the bioavailability of MA administered orally at relatively low doses (1–7 mg kg−1). Pluronic-based microgels (spherical gel particles of sub-millimetre size) were introduced as MA vehicles. The microgels comprised a cross-linked network of poly(acrylic acid) onto which the Pluronic chains were covalently attached. Microgels of Pluronic L92 and poly(acrylic acid) fabricated into tablet dosage forms exhibited dramatically lowered MA initial burst release. The MA release was pH-dependent owing to the pH sensitivity of the microgel swelling, with the drug retained by the microgel at pH 1.8 and released slowly at pH 6.8. In the rat model, a significant increase in MA bioavailability was observed when the microgel-formulated MA was administered orally at a high dose of 10 mg kg−1, owing to the enhanced retention of the microgel. The study of the microgel passage through the gastrointestinal tract demonstrated the microgel retention characteristic of a very high molecular weight polymer and the absence of any systemic absorption of the polymer.

Effects of megestrol acetate and testosterone on body composition in castrated male Sprague-Dawley rats

The interrelationships among sex hormones, caloric intake, and intermediary metabolism in health and disease are uncertain. Studies in malnourished patients with AIDS and cancer show that megestrol acetate (MA) therapy increases appetite, body weight, and body fat, while it decreases serum testosterone (T) concentration. In this study, the separate and combined effects of MA and T were investigated in 65 young adult, male, castrated, Sprague-Dawley rats who received subcutaneous implants containing placebo, MA, T, or both MA and T for 11 wk. By hierarchical multiple regression analysis, MA therapy decreased weight gain and food intake (P < 0.01), increased body fat (P = 0.024), decreased body protein (P < 0.001), and decreased the portion of calories accrued as protein rather than fat (P ratio, P < 0.03). T alone decreased fat (P < 0.03), but had no significant effect on food intake, the relative number of consumed calories utilized for growth (food efficiency), body weight, or protein. The interaction of MA and T did not affect food intake or food efficiency, but increased body weight (P < 0.02), protein (P < 0.05) and the P ratio (P < 0.02). The portion of weight gain as fat was reduced from 47.3% with MA alone to 27.4% when MA and T were combined. Thus, megestrol acetate has significant antianabolic effects that are independent of its effects upon food intake. The addition of testosterone to megestrol acetate partially antagonized MA's inhibition of lean mass accretion in these rats.

Changes in serum sex steroid levels during megestrol acetate therapy

We hypothesized that megestrol acetate (MA) may work on breast carcinoma by inducing changes in serum sex steroid levels. We prospectively measured levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), dehydroepiandrosterone (DHEA), estrone (E1), and estradiol (E2) in 18 postmenopausal women before and during megestrol acetate therapy. MA significantly suppressed serum FSH, LH, DHEA and E1 levels. However, this was accompanied by a marked increase in serum E2 levels as measured by radioimmunoassay performed on whole serum. MA did not cross-react with the anti-E2 antibodies used in the assay. Elevated E2 levels also occurred in oophorectomized and/or adrenalectomized patients indicating the ovary and adrenal are not the source of the elevated E2 levels. We conclude that MA may be metabolized to oestrogenic compounds that crossreact with antibodies to E2, explaining the elevated E2 levels observed. The effects of these oestrogenic metabolites on breast carcinoma are unknown.

Relevance of quality of life assessment to the evaluation of combined-modality therapy

Quality of life (QOL) assessment is a research tool which is incorporated into clinical trials to provide information about the ways in which the treatment affects the individuals sense of well-being and his physical, psychologic, and social functions. In the appropriate setting QOL assessment offers additional endpoints, beyond the traditional response rates and survival durations, to evaluate cancer treatments in ways which can be particularly meaningful to patients. Selected aspects of QOL methodology and the application of QOL assessment to the evaluation of combined-modality therapies for gastrointestinal cancers are discussed.

Cachexia and cancer: a clinician's view

The cancer-related cachexia/anorexia syndrome is not well understood. It is related to several factors like metabolic changes, tumor types, and disease extent and is frequently accompanied by decreased performance status. An important aspect of anorexia is the psychosocial problem: the patient is unable to join the family for meals precisely when he or she most needs familial support. Several randomized studies have shown that megestrol acetate, possibly in a dose-dependent fashion, can improve appetite and lead to weight gain. This effect seems to be most prevalent in patients with breast cancer and also occurs in the absence of a tumor response. We have retrospectively analyzed 176 patients with cancer types other than breast cancer who received only palliative treatment. The patients were treated with megestrol acetate (160 mg tid) because they complained of anorexia. After 10 days of treatment, megestrol acetate was continued only in those patients whose appetite and/or general well-being improved. Fifty-seven patients (32%) experienced such an improvement and asked for continuation of therapy. Many basic questions are still unanswered; nonetheless, from a practical clinical view it seems worthwhile to offer anorectic patients a chance to improve, especially since side effects of megestrol acetate are absent or mild, and the distinction between responders and nonresponders can be made by 10 days of treatment.

Progesterone receptors in carcinomas of the upper aerodigestive tract

This study had three major goals: (1) to vigorously verify the presence of progesterone receptors in squamous cell carcinoma of the upper aerodigestive tract (HN-SCC). Antiprogesterone receptor monoclonal antibodies revealed a distinct band at approximately 120 kilodaltons in samples taken from two of four patients with HN-SCC. These results illustrate that progesterone receptor in HN-SCC has the same molecular weight as progesterone receptor in normal human uterus and human breast cancer. Steroid specificity and saturability results support the evidence that it is true progesterone receptors that are measured and not other receptors or sex steroid-binding globulins; (2) to confirm the biochemical function of progesterone receptors in HN-SCC by assessing the binding of progesterone receptor to acceptor sites on chromosomes in the nucleus; and (3) to establish the clinical significance of progesterone receptor measurement. Patients with positive assays were more likely to be free of disease a mean of 6 months after resection. We used logistic regression to account for site of primary disease, grade of tumor, and stage of disease. This logistic regression was significant with a p = 0.014. Patients with a binding index greater than 2 (19 of 73 patients) were 4.34 times more likely to be free of disease than patients with negative assays.

Jaundice and intrahepatic cholestasis following high-dose megestrol acetate for breast cancer

High-dose megestrol acetate, a synthetic progestin, has been advocated recently in treating patients with metastatic breast carcinoma; no significant increase in adverse effects has been reported. This report describes a patient with jaundice and intrahepatic cholestasis after high-dose megestrol acetate therapy. This cholestatic lesion may have a pathogenesis similar to that observed with estrogens and oral contraceptives.

Plasma concentrations of medroxyprogesterone acetate and megesterol acetate during long-term follow-up in patients treated for metastatic breast cancer

A total of 32 patients with metastatic breast cancer responding with at least disease stabilization to treatment with two commercially available preparations of medroxyprogesterone acetate (MPA) or one preparation of megestrol acetate (MA) were followed for their plasma concentrations. The MPA and MA were measured by HPLC. MPA from Upjohn and Farmitalia was given to 12 patients (median age, 61 years; median follow-up, 20 weeks) and 8 patients (54 years, 16 weeks), respectively, on a schedule of 1000 mg daily i.m. for 10 days followed by 200 mg t.i.d.p.o. for the remainder of the treatment course. The peak concentrations (means, 163 vs 97 ng/ml), the time to peak levels (medians, 3 vs 10 weeks), and the areas under the concentration curves from time 0 to 24 weeks (means, 2400 vs 1868 ng/ml X weeks) were significantly different in the respective treatment groups (t-test; significance level, 0.05). MA from Bristol-Myers was administered orally in one daily dose of 160 mg throughout the treatment course in 12 patients (median age, 51 years; median follow-up, 20 weeks). A mean MA peak concentration of 218 ng/ml was reached after a median of 7 days. Plateau plasma levels were higher for MA than MPA.

Oral high-dose medroxyprogesterone acetate versus tamoxifen. A randomized crossover trial in postmenopausal patients with advanced breast cancer

In a prospective randomized multicenter study in previously untreated postmenopausal patients with advanced breast cancer, the response to treatment with oral medroxyprogesterone acetate (MPA) 300 mg three times daily was compared with tamoxifen (TAM) 20 mg twice daily. Of 61 patients treated with MPA, 27 (44%) had a partial or complete remission, 6 showed no change, and 28 had progressive disease. Of 68 patients treated with TAM, 24 (35%) showed a remission, 15 no change, and 29 progression. The difference in response rate is not significant. However, 11 of 25 patients with osseous metastases as predominant site, responded to MPA and 7 of 31 to TAM (P = 0.05). Moreover, in patients older than age 70 years, 13 of 26 responded to MPA and 6 of 31 to TAM (P less than 0.05). Median duration of remission of all patients in the MPA arm was 17 months and in the TAM arm, 23 months (not significant). Median survival was 20 months for MPA and 26 months for TAM (not significant). After cross-over from TAM to MPA 8 of 31 patients responded and after cross-over from MPA to TAM, no response was seen in 27 patients. These data indicate that the response rate and duration to MPA and TAM are comparable, except in patients with osseous metastases and in patients older than age 70 years. MPA has more side effects, but seems to be more effective after cross-over, and may thus be reserved for second-line treatment.

[Megestrol acetate in various doses in the treatment of metastatic breast carcinoma--clinical and endocrinologic studies]

Both medroxyprogesterone acetate (MPA) and megestrol acetate (MA) are effective in the treatment of metastatic breast cancer. Although the dose-dependent mode of actions of MPA have been extensively clarified, there is still some uncertainty regarding the mode of actions and dosage of MA. Thirty-three patients with metastatic breast cancer were treated with various dosages of MA under a phase-II study. Eight patients were given 200 mg, 9 X 400 mg, 10 X 600 mg and 6 X 800 mg MA daily per os. The LH, FSH, TBI, T3, T4, TSH, ACTH, aldosterone, testosterone, prolactin and cortisol levels were determined regularly during treatment to enable the investigation of the pharmacodynamics of MA. A complete remission was achieved in two patients, a partial remission in seven patients and there was no change in eight patients (total responder rate 51.5%). The clinical and endocrine changes therefore suggest that the dose-dependent mode of actions of MPA and MA are identical. Equivalent dosages of MPA are 1000-1500 mg per os and of MA 160-200 mg. Furthermore, similar relationships between the endocrine changes and remission behaviour of MA and MPA have been observed. Persisting tumour remissions are inevitable under cortisol suppression and normal prolactin, aldosterone and ACTH levels.