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Results for “Medroxyprogesterone Acetate--pharmacodynamics”

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At least 19 recordsLinked to original sources
PubMed1984

Return of ovulation following a single injection of depo-medroxyprogesterone acetate: a pharmacokinetic and pharmacodynamic study.

The effect of a single dose of 150 mg of depo-medroxyprogesterone acetate (DMPA) on pituitary, ovarian and endometrial function was assessed in relation to the peripheral levels of the compound in 8 women. The levels of medroxyprogesterone acetate (MPA), follitropin (FSH), lutropin (LH), prolactin, estradiol (E2) and progesterone ( Prog .) were measured 3 times a week during a pretreatment (control) cycle and then daily during postinjection weeks 14-17, 22-25 and 30-33. An endometrial biopsy specimen was obtained during postinjection weeks 17, 25 and 33. In three out of 8 subjects the daily hormone assays carried out during postinjection weeks 30-33 indicated anovulatory periods; in these subjects peripheral blood was drawn daily during postinjection weeks 46-49 and a fourth endometrial biopsy was taken during week 49.

Adult↗
PubMed1995

A comparative study on the return to ovulation following chronic use of once-a-month injectable contraceptives.

A comparative study was undertaken involving 21 Mexican women who discontinued the use of medroxyprogesterone acetate 25 mg plus oestradiol cypionate 5 mg (Cyclofem) and norethisterone enanthate 50 mg plus oestradiol valerate 5 mg (Mesigyna) to assess the time required for the return to menses and ovulation. All subjects were exposed to once-a-month injectable contraceptives for two years and were followed for 120 days after the last injection. The urinary concentration of oestrone glucuronide and pregnanediol glucuronide was determined daily in all subjects beginning one month after the last injection. The results disclosed that ovulatory cycles were documented after 120 days of the last injection in six women of each studied group. Similar endometrial bleeding patterns were observed in both groups, indicating that the two drugs have alike pharmacokinetic and pharmacodynamic effects.

Adult↗
PubMed1990

High progesterone receptor concentration in a variant of the ZR-75-1 human breast cancer cell line adapted to growth in oestrogen free conditions.

Culture of ZR-75-1 human breast cancer cells for 5 days in the absence of oestrogens (phenol red-free medium supplemented with dextran coated charcoal stripped 5% fetal calf serum) resulted in a slowing of growth rate and loss of progesterone receptors. Oestradiol at 10(-9) M markedly stimulated growth and progesterone receptor synthesis over a 5-day period. While medroxyprogesterone acetate (10(-10) to 10(-6) M) inhibited growth of ZR-75-1 cells growing in complete medium, in the short-term absence of oestrogens low concentrations were growth stimulatory. Cells deprived of oestrogens for 5 days retained sensitivity to growth inhibition by 4-hydroxy tamoxifen. ZR-75-1 cells were also adapted to growth in the absence of oestrogens over a 5-month period. These cells (ZR-PR-LT) failed to express binding sites characteristic of the type 1 oestrogen receptor but progesterone receptor expression was at a level normally associated with oestrogen induction. Adapted cells were growth inhibited by oestradiol, 4-hydroxy tamoxifen and medroxyprogesterone acetate, but despite elevated progesterone receptor expression the progestin was only marginally more inhibitory than in the parent line. Our data indicate a poor quantitative relationship between response to progestins in vitro and progesterone receptor concentration and support previous findings that acquisition of an oestrogen independent phenotype does not necessarily result in resistance to anti-oestrogens.

Antineoplastic Agents↗
PubMed1992

Concentration of fat, protein, lactose and energy in milk of mothers using hormonal contraceptives.

Energy, protein, lactose and fat were studied in the milk of mothers who were using different types of contraceptives. One hundred and eleven mothers made up the following groups. C: control (barrier and natural methods, or sterilization), n = 22; combined pill: LDP (low dose pill (levonorgestrel 0.15 mg + ethinylestradiol 0.03 mg)), n = 12 and MDP (medium dose pill (levonorgestrel 0.25 mg + ethinylestradiol 0.05 mg)), n = 13; MP (minipill (norethindrone 0.35 mg)), n = 37; DMPA (injectable progesterone (depot medroxiprogesterone acetate 150 mg)), n = 17; and IUD (plastic or copper intrauterine device), n = 10. The mean stages of lactation were, respectively, 15, 17, 5, 9, 5 and 9 weeks. The mean duration of observation for the study groups ranged from 2 to 4 weeks. Milk samples were collected before and after initiation of treatment (mean = 20 days; range = 14-103 days). The stage of lactation and the interval of nursing before sampling were recorded so that statistical account could be taken of these uncontrollable sources of variability. When incorporated as covariates, they showed that no significant differences existed between the groups tested, either before or after treatment.

Adult↗
PubMed1989

Opioidergic regulation of LH pulsatility in women with polycystic ovary syndrome.

Women with polycystic ovary syndrome (PCO) display disordered patterns of LH pulsatility and may have an impairment of opioidergic regulation of GnRH-LH. In order to ascertain if these patterns reflect an inherent hypothalamic abnormality or a functional state consequent to the acyclicity of sex steroids, LH pulsatility and gonadotrophin responses to naloxone were examined in six PCO women before and after treatment with incremental daily doses of a progestogen, medroxyprogesterone acetate (MPA), for 10 days to determine (i) if progestogen treatment would alter the LH pulse pattern to resemble that of the luteal phase; and (ii) if the conversion to a luteal phase LH pulse pattern by MPA would involve the induction of opioidergic regulation. LH pulsatility and FSH levels were determined by blood sampling at 10 min intervals for 8 h before and after MPA treatment during a saline infusion on the control day and during a naloxone infusion (1.6 mg/h) on the following day. Basal levels of oestradiol, oestrone, androstenedione, testosterone, and dehydroepiandrosterone-sulphate were measured before and after MPA. All six PCO women responded to MPA administration with a significant reduction in LH pulse frequency (P less than 0.005), an increase in LH pulse amplitude (P less than 0.0025), and an increase in LH pulse duration (P less than 0.025), without changes in mean LH, mean FSH, androgen, or oestrogen levels. Thus, a luteal phase LH pulse pattern was induced by MPA. Naloxone reversed the MPA-induced changes in LH pulsatility, indicating that these responses involved the induction of central opioidergic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Comparative assessment of the effects of subdermal levonorgestrel implant system and long acting progestogen injection method on lipid metabolism.

In order to compare the effects of two type of long-acting progestogen contraceptive methods with subdermal levonorgestrel (LNG) implants and depot-medroxyprogesterone acetate (DMPA) injections on lipid metabolism, a clinical cohort study was performed by requiring 25 women in each group adopting either LNG implant or DMPA injection method voluntarily. After 6 months of use, serum levels of triglycerides, total cholesterol, HDL-cholesterol and LDL-cholesterol were determined and compared between the two groups of acceptors. The mean of total cholesterol in LNG implant acceptors was significantly lower than that in DMPA injection acceptors. The mean values of HDL-cholesterol in LNG implant acceptors (41.7 +/- 7.7 mg/dl) and in DMPA injection acceptors (45.0 +/- 9.0 mg/dl) were in the normal range without significant difference between the two groups. The mean value of triglycerides did not differ significantly between LNG implant acceptors (77.6 +/- 25.1 mg/dl) and DMPA injection acceptors (91.0 +/- 30.3 mg/dl). Serum concentrations of lipid fractions such as HDL-cholesterol and LDL-cholesterol in LNG implant acceptors were relatively low compared to those in DMPA injection acceptors. Since there was a comparable reduction in both total-and HDL-cholesterol levels in the LNG implant group, the ratio of total-to HDL-cholesterol, which is thought to be a factor in determining the risk of coronary artery disease, remained in the normal range (2 +/- 4.5). This suggests that the use of these two contraceptive methods with progestogens does not alter the risk of development of coronary artery disease.

Adolescent↗
PubMed1978

Effects of a long-acting progestin on reproductive function in female mice.

The duration of activity of a long-acting progestin, medroxyprogesterone acetate, was compared using three tests for progestational activity: the induction of stromal mitosis in the endometrium, implantation of blastocysts and inhibition of ovulation. The duration of activity was similar in each test and was longer when higher doses were given.

Animals↗
PubMed1977

Adrenocortical involution in rats during oestrus synchronisation with medroxyprogesterone.

Daily treatment of female rats with medroxyprogesterone acetate in aqueous suspension resulted in adrenocortical atrophy. The doses given were those used for oestrus synchronisation. Intramuscular injections of 2-0 mg medroxyprogesterone acetate were used to investigate the atrophic process. Adrenocortical involution was associated with extensive single cell deletion (apoptosis). It is suggested that theses changes were due to suppression of pituitary ACTH secretion. The cytological changes support the concept that single cell death plays an important role in organ remodelling. Biochemical determinations of DNA, RNA, protein and dry matter, and histological examination, did not reveal significant changes in the liver.

Adrenal Cortex↗
PubMed1977

Effects of long-acting steroid contraceptives on ovarian and uterine histology of rats.

Subcutaneous injection of single doses (5 to 20 mg/kg) of DMPA or NE in virgin female rats caused reduction in number and diameter of CL, and increase in number of atretic and cystic follicles in the ovary. Histological examination of the endometrium of these animals showed low cubiodal cells with sparse distribution of low columnar cells, glands with atrophic changes and compact uterine stroma with or without patches of oedema. The results suggest regressive and atrophic changes in the ovary and endometrium.

Animals↗
PubMed1982

Long acting injectable hormonal contraceptives.

Injectable hormonal preparations can be highly effective and satisfactory contraceptives. The two main preparations available today are depot medroxy progesterone acetate (DMPA) and norethisterone oenanthate (NET-OEN), but several other approaches are currently under clinical trial. Injectable contraceptives have some unique advantages which give them justifiably wide appeal amongst many groups of women. However, they do have a number of disadvantages including invariable menstrual disturbance and a delay in the return of fertility. One formulation of DMPA, Depo-Provera, is probably the most extensively investigated single hormonal contraceptive ever made. These studies indicate that it is remarkably safe and does not face any more unresolved issues than the combined pill, intrauterine device or tubal sterilization. However, for a number of disparate emotional and political reasons it has attracted the attention of several consumer and feminist groups, who have waged a prolonged and quite unjustified campaign against it. It is to be hoped that future debate will be conducted on a more informed, rational and less emotional basis. Injectable contraceptives should have an important place in the family planning armamentarium of all countries, and current developments should lead to a decrease in concerns about presently available agents. This should further increase the widespread acceptability of this approach to contraception.

Animals↗