The pharmacokinetics of high-dose medroxyprogesterone acetate (MPA) in the therapy of advanced breast cancer

Depot-medroxyprogesterone acetate: an update

OBJECTIVE

Depo-Provera is a contraceptive approved by the US Food and Drug Administration (FDA) since 1992 and used worldwide by more than 90 million women.

AIM OF STUDY

Despite the fact that progestins are endogenous hormones that are secreted by the body, its excess might lead to detrimental health effects. Whether progestins as contraceptives are friends or foes is a questionable matter. In this manuscript, we drive the attention to both usage and side effects Depo-Provera.

RESULTS

Depot-medroxyprogesterone acetate (DMPA) is a highly effective, convenient non-daily hormonal contraceptive option that has been available worldwide for many years. The experience with DMPA provides a large body of long-term data regarding the efficacy and safety of this contraceptive method; this long-term experience has established that the use of DMPA does not increase the risk of cardiovascular events, breast cancer, other gynecologic malignancy, or postmenopausal fracture; however, patients are often more concerned about the relatively immediate effects of contraceptives such as potential changes in menstrual cycle, body weight, and mood disturbances.

CONCLUSION

Concerns about such issues may lead to reluctance to initiate therapy or premature discontinuation. Counseling and understanding of women's concerns and experiences using Depo-Provera is important and could help health care providers redesign counseling strategies to improve contraceptive continuation and improve patient adherence.

Medroxyprogesterone acetate reduces the in vitro production of cytokines and serotonin involved in anorexia/cachexia and emesis by peripheral blood mononuclear cells of cancer patients

Medroxyprogesterone acetate (MPA) is widely used in oncology both in the treatment of hormone-related cancers and as supportive therapy in anorexia/cachexia syndrome (ACS), but conclusive data are not yet available to explain its anticachectic effect. ACS is characterised by weight loss, changes in metabolism, reduction of appetite, nausea and vomiting. Several cytokines, mainly interleukin (IL)-1, IL-2, IL-6 and tumour necrosis factor alpha (TNF alpha), are involved in the pathogenesis of ACS. Additionally, nausea and vomiting can be mediated by factors inducing serotonin (5-HT) production and/or release by pleiotropic cells including activated T lymphocytes. In the present study, we report the effect of MPA on peripheral blood mononuclear cells (PBMC) from 10 cancer patients in advanced stage of disease (6 head and neck, 2 colon, 1 lung and 1 ovary). The proliferative response of PBMC to PHA, anti-CD3 monoclonal antibody (MAb) or recombinant IL-2 (rIL-2), the production of IL-1 beta, IL-2, IL-6, TNF alpha and 5-HT by PHA-stimulated PBMC and the expression of lymphocyte membrane-bound IL-2 receptor (IL-2R) subunities (CD25 and CD122) were studied. The addition of MPA significantly reduced the PBMC proliferative response to PHA and anti-CD3 MAb but not to rIL-2. MPA 0.2 microgram/ml was also capable of reducing the levels of IL-1 beta, IL-6, TNF alpha and 5-HT produced in culture by PHA-stimulated PBMC, whereas it did not induce any change in the percentage of PBMC expressing either CD25 or CD122 or both molecules after stimulation with PHA or anti-CD3 mAb.

The pharmacokinetics of medroxyprogesterone acetate following two different loading dose schedules in advanced carcinoma of the breast

A loading dose of MPA employing a regimen of 1,000 mg six hourly for 8 doses can achieve plateau levels above 100 ng ml-1 within the first 36 h of treatment, without any untoward toxicity. This raises the possibility of shortening the time to response for this agent. The additional factor of the time required to achieve adequate serum levels may explain the apparent contradictions between reports correlating response rates and dose and those correlating serum level and response.

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.

Lack of correlations between plasma concentration of medroxyprogesterone acetate, hypothalamic-pituitary function, and tumour response in patients with advanced breast cancer

Plasma medroxyprogesterone acetate (MPA) concentrations were measured in 61 patients with advanced breast cancer, after 3 weeks' treatment using 200 mg PO 8-hourly, to determine whether the previously reported wide interpatient variations correlated with tumour response or toxicity. Seventeen patients (28%) responded to the drug, and their mean plasma MPA concentration was 97 ng/ml +/- 68 SD, compared with 115 ng/ml +/- 87 SD for the patients whose disease progressed. Side-effects attributed to MPA were seen in 18 patients, who had a mean drug concentration of 113 ng/ml +/- 104 SD. This was not significantly higher than that of the patients who did not experience drug toxicity. Because of a suggestion that some of the antitumour activity of the drug could be mediated via an effect on the hypothalamic-pituitary axis, we also measured plasma FSH, LH, and prolactin concentrations after the 3-week treatment with MPA, but found no correlations with either drug concentration or tumour response. These results indicate that with the present treatment schedule the monitoring of plasma MPA concentrations has no role in routine practice and suggest that the inherent sensitivity of the tumour to progesterone is probably the major determinant of response.

Pharmacokinetic and pharmacodynamic basis for the treatment of metastatic breast cancer with high-dose medroxyprogesterone acetate

Postmenopausal patients with metastatic breast cancer were treated with medroxyprogesterone acetate (MPA) (Clinovir) in dosages between 500 and 1500 mg orally per day. The relation of MPA plasma concentrations and endocrine effects were studied in a longitudinal fashion. MPA exerted suppressive effects on the basal and gonadotropin-releasing hormone (GnRH) stimulated gonadotropin secretion, cortisol, dehydroepiandrosterone (DHEA), and estradiol (E2) in a dose-dependent manner leading to a complete suppression with 1500 mg orally per day. The depression of thyroid hormones (T3 and T4) coincided with a depression of the thyroxine-binding index (TBI). MPA did not affect human growth hormone (hGH), basal and thyrotropin-releasing hormone (TRH) stimulated thyroid-stimulating hormone (TSH) and aldosterone. Basal and TRH-stimulated prolactin (PRL) secretion showed a slight but distinct elevation. From these data it is concluded that in postmenopausal patients MPA exerts its antitumor activity by an interference with the hypothalamo-pituitary adrenal axis in the sense of a selective pharmacologic hypophysectomy leading to complete suppression of adrenal steroid secretion. Additionally, MPA inhibits tumor cell growth through the progesterone receptor. A dual mechanism for the antitumor activity of high dose is postulated MPA: ablative through suppression of the hypothalamo-pituitary-adrenal axis and subsequent estrogen deprivation, and additive via the progesterone receptor directly on the tumor cell. The significance of gonadotropin suppression in the postmenopause for breast cancer growth is unclear. The depression of T3 and T4 is due to a depression of thyroid hormone-binding proteins. The elevation of PRL secretion may be explained by a slight estrogenic activity of MPA metabolites.

Medroxyprogesterone acetate (MAP) plasma levels after multiple high-dose administration in advanced cancer patients

Medroxyprogesterone acetate plasma levels were measured in advanced cancer patients after multiple PO or IM administration (500, 1000, 2000, 3000, 4000, and 5000 mg/day PO and 500, 1000, 2000 mg/day IM for 30 days). After PO administration, the plasma concentration rises quickly and plateau level is reached in 4-10 days. Discontinuation of the treatment produces a fast decay (t1/2 = 62.4 h) of the drug levels. When medroxyprogesterone acetate is given IM plasma levels, steadily increase and after drug discontinuation no noticeable decay is observed for at least 6 months; plateau plasma levels are about three times higher than after the corresponding PO treatment. Extremely high interpatient variation in bioavailability is present with both administration routes. These data may well rationalize the results of previous clinical trials and will help in planning treatment schedules.

[High dose medroxyprogesteroneacetate in metastasizing breast cancer: correlations between course of the disease and hormone profiles]

Based upon preliminary observations that tumor response to MPA was correlated to cortisol suppression 42 patients were treated with MPA at different dose levels. 1500 mg MPA p.o. almost completely suppressed endogenous cortisol production in 23 out of 23 patients. Consequently, 51 patients with advanced stage metastatic breast cancer were treated with Medroxyprogesteroneacetate (HD-MAP) at a dosage of 1500 mg p.o. daily or 500 mg i.m. on 5 days per week. There were 5 complete and 7 partical remissions, 23 patients with no change and 10 with progressive disease. 7 patients were not evaluable. Clinical results correlated to plasma cortisol and prolactin blood levels bot not to LH, FSH, TSH, TBI, T3, T4, ACTH and aldosterone measurements. There was no patient with relapse and suppressed cortisol or normal prolactin measurements. The development of pituituary resistance to MPA is suggested. HD-MPA was equally effective in estrogen and/or progesterone receptor positive as in receptor negative patients. It is proposed that cortisol and prolactin determinations are useful to monitor for effective MPA treatment and the early detection of MPA resistance.

Plasma concentrations of megestrol acetate and medroxyprogesterone acetate after single oral administration to healthy subjects

Plasma concentrations of megestrol acetate (MA) were measured by radioimmunoassay (RIA) after a single oral dose of 60 mg either in the form of one tablet, or four 15 mg tablets, to 10 women 21-40 years old using a cross-over design. No statistically significant difference between the two preparations was observed with respect to plasma concentrations, the area under the curve from 0 to 24 h or the maximum concentration (c(max)). For comparison, data are presented on the plasma level of medroxyprogesterone acetate (MPA) following a single oral dose of 100 mg given using a cross-over design in two different tablet forms to 10 healthy men, when no significant difference was observed for these parameters. The mean c(max) for MA after 2.6 h was 43.9 ng/ml (range 21.7-87.7 ng/ml), whereas that for MPA at 3.1 h was 13.1 ng/ml (range 4.4-29.5 ng/ml) despite the higher dose. After 24 h immunoreactive MA and MPA ranged from 9.6 to 29.0 ng/ml and from 0.2 to 4.0 ng/ml respectively. Moreover, it was found that petroleum ether extraction gives the most specific result by RIA, although considerable amounts of metabolites are still co-estimated. By comparison with selected ion monitoring using GC-MS, metabolite interference in RIA increases with time after administration of the steroids and is considerably greater for MPA than for MA. It is concluded that after oral administration the relative bioavailability of MA is significantly better than that of MPA.