Oral contraceptive use and risk of colorectal cancer

To evaluate the relation between oral contraceptives and colon and rectal cancer, we analyzed combined data from two case-control studies conducted in six Italian regions between 1985 and 1996. The studies included 803 women with incident colon cancer, 429 with rectal cancer, and 2,793 controls with acute, nonneoplastic, nondigestive, non-hormone-related disorders. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) from unconditional multiple logistic regression equations, including terms for age, center/study period, education, family history of colorectal cancer, menopausal status, age at menopause, parity, use of hormone replacement therapy, body mass index [weight (kg) per height squared (m2)], and total energy intake. Ever-use of oral contraceptives was inversely associated with colon cancer (OR = 0.63; 95% CI = 0.45-0.87) and rectal cancer (OR = 0.66; 95% CI = 0.43-1.01). Duration of use of oral contraceptives was inversely related to risk of colon but not rectal cancer. This study suggests that women who have ever used oral contraceptives are at lower risk of colon and rectal cancer.

Bioavailability of orally administered sex steroids used in oral contraception and hormone replacement therapy

The concept of bioavailability is discussed with particular references to the sex steroids. Problems encountered in the measurement of bioavailability of these steroids and the various factors that may affect their bioavailability are briefly described. Information regarding the bioavailability of the estrogens and gestogens, some of which are prodrugs, used in oral contraception and hormone replacement therapy is summarized and the implications regarding the clinical use of these steroids are discussed.

[Hormonal contraception and substitution therapy: the importance of progestogen for cardiovascular diseases]

Epidemiological data have demonstrated, that the progestogen component of oral contraceptives is involved in the development of hypertension, ischaemic heart diseases and stroke. It had been suggested, that atherosclerotic lesions due to the unfavourable effect on lipid metabolism of progestogens with androgenic properties, play a causal role. It has, however, been shown, that there is no development of atherosclerosis despite reduced HDL and elevated LDL, presumably because of the induction of hepatic LDL- and remnant-receptors by the strong effect of ethinyl-oestradiol upon the liver. A series of experimental and clinical findings indicates that vasospasms caused by the vasoconstrictory effect of progestogens are involved in the development of arterial thromboses. In postmenopausal women, the additional administration of progestogens to the oestrogen treatment may trigger ischaemic diseases, particularly in the presence of vascular lesions. Oestrogens exercise a pronounced vasodilatory effect and stabilize the vascular tonus--through changes in the responsiveness of endothelium and smooth muscle cells to vasoactive compounds, through modulation of neurotransmitter release from nerve endings, and through direct blocking of calcium channels. The effects depend essentially on an intact endothelium. By a direct action on the vascular wall, progestogens increase the sensitivity of arteries to vasoconstrictory compounds and reduce blood flow. As aldosterone increases the number of beta-adrenergic receptors in the arterial smooth muscle cells and thus act vasodilatorily, it cannot be excluded, that progestogens with high affinity to the aldosterone receptor and antimineralocorticoid properties, may exert a strong vasoconstrictory effect.(ABSTRACT TRUNCATED AT 400 WORDS)

Oral contraceptive-induced lupus erythematosus in a Japanese woman

A case of oral contraceptive-induced lupus erythematosus (LE) was reported. Erythematous skin lesions were noticed on hypothenor sites of palms and acral sites of pedes. Abnormal laboratory findings included an elevated ESR, CRP and weakly positive anti-nuclear antibodies. Skin biopsy specimens from involved skin showed Clq deposits at the dermo-epidermal junction. LE-like symptoms were considered to be induced by oral contraceptives, because her symptoms disappeared after the oral contraceptives were discontinued.

Interactions with oral contraceptives

The interaction of a range of different factors with the pharmacologic activity of oral contraceptives is reviewed. Pharmacokinetic interactions with oral contraceptives may occur (1) during absorption and extrahepatic circulation, (2) by interfering with protein binding, and (3) during hepatic metabolism. The hepatic mixed function oxidase system, which is mainly responsible for the metabolism of oral contraceptives, is affected by several different factors and is easily induced. Nutrition affects the activity of many drugs, but information regarding oral contraceptives is meager. Both pharmacokinetic and pharmacodynamic interactions, which may be synergistic or antagonistic, between the estrogen and gestagen components of oral contraceptives, are important, but there is no correlation between the rate of metabolism of the two components. Evidence suggests that some anticonvulsant, antibiotic, and antibacterial drugs may reduce the efficacy of oral contraceptives. Instances of interactions of other therapeutic agents are reported infrequently. The incidence of serious interactions is low and does not appear to have been reduced with low-dose oral contraceptives, probably because of large intersubject variability in the pharmacokinetics of oral contraceptives.

Gastrointestinal disease and oral contraception

Oral contraceptive steroids play a major role in modern family planning. With the present tendency to decrease the doses of both estrogens and progestogens, any factor that reduces the bioavailability of the lower-dose preparations may have an impact on contraceptive protection. Although ethinyl estradiol, the most commonly used oral estrogen, is liable to an enterohepatic circulation as unchanged drug, the commonly used progestogens are not. At present, no convincing evidence exists in the human subject that disruption of the enterohepatic circulation by antibiotics or antacids does reduce contraceptive efficacy of the pill. Oral contraceptive steroids are mainly absorbed from the small bowel, and contraceptive efficacy depends on its absorptive capacity. Enhanced passage of gastrointestinal contents or impaired absorption may thus contribute to contraceptive failures in patients who have chronic inflammatory disease, diarrhea, ileostomy, or jejunoileal bypass.

The effect of oral contraceptive use and pregnancy on the daily rhythm of cortisol and cortisone

The effect of oral contraceptives and of pregnancy on the daily rhythm of cortisol, and its metabolite cortisone in plasma and saliva has been investigated. In both conditions the total plasma cortisol levels were raised to the same extent, the mean values in saliva in the oral contraceptive users being intermediate between those in pregnancy and in the controls, particularly in the morning. Salivary cortisone levels were more related to salivary cortisol than to total plasma cortisone which exhibited a rather flat daily rhythm. There was a shift in peak values for salivary cortisol and cortisone towards late morning: this may be due to a delay in the daily activation of the hypothalamic-pituitary-adrenal axis in these patients.

Pharmacokinetics of oestrogens and progestogens

There are large inter- and intra-individual variations in the serum concentrations of natural and synthetic sex steroids irrespective of the route of administration. Oral ingestion of steroids has a stronger effect on hepatic metabolism than parenteral administration, as the local concentration in liver sinusoids are 4-5 times higher during the first liver passage. Oestradiol and oestrone are interconvertible, dependent on the local concentrations in liver and target organs, and oestrone sulphate serves as a large reservoir. The oestrone/oestradiol ratio has no physiological significance, as oestrone is only a weak oestrogen. Oestrone is both a precursor and a metabolite of oestradiol. Oestriol is extensively conjugated after oral administration. Therefore, the oestriol serum levels are similar after oral intake of 10 mg and after vaginal application of 0.5 mg oestriol resulting in similar systemic effectiveness. Conjugated oestrogens can easily enter the hepatocytes but are hormonally active only after hydrolyzation into the parent steroids. Ethinylestradiol which exerts strong effects on hepatic metabolism and inhibits metabolizing enzymes, should not be used for hormone replacement therapy. Among the progestogens, the progesterone derivatives have less effects on liver metabolism than the norethisterone derivatives (13-methyl-gonanes and 13-ethyl-gonanes). The highly potent 13-ethyl-gonanes are effective at very low doses, because of a slow inactivation and elimination rate due to the ethinyl group.

Selected aspects of the pharmacokinetics and metabolism of ethinyl estrogens and their clinical implications

Careful studies in an adequate sample of subjects show a very marked degree of variability in the pharmacokinetics of ethinyl estradiol--specifically, in parameters such as area under the curve, half-life, and time to peak. This variability is seen in differences between different populations, as well as from one individual to another. These studies also show variability in area under the curve and other parameters in the same person from time to time. Such differences may equal or exceed the differences between low dose (35 micrograms) and high-dose (50 micrograms) formulations. The levels of plasma ethinyl estradiol produced by a 50 micrograms dose of mestranol are similar to those from 35 micrograms of ethinyl estradiol. Thus a high-dose pill may be no higher than a low-dose pill if the nature of the estrogen is not kept in mind. Qualitative differences in the oxidative metabolites of estrogens may be of significance with respect to oncogenic potential.

Pharmacokinetics of gestagens: some problems

Various approaches to studying the pharmacokinetics of gestagens and the factors that influence derivation of the parameters are described with levonorgestrel used as an example. Published studies of the pharmacokinetics of levonorgestrel are reviewed, and new information is presented regarding intra- and intersubject variation. Differences between various formulations of levonorgestrel are apparent when the formulations are compared in the same subjects. There is also a marked difference in the parameters when derived under single-dose or steady-state conditions. The role of sex hormone-binding globulin in the metabolism of levonorgestrel is questioned. Large intra- and inter-subject variations in the parameters exist, and a subject may show a large month-to-month variation when one levonorgestrel formulation is used and smaller variations when another formulation is used. This wide variability in the pharmacokinetic parameters, problems that arise in the derivation and interpretation of the parameters, the biologic significance of most of these parameters, and their lack of correlation with pharmacodynamic responses severely limit the usefulness of pharmacokinetic studies of the gestagens.

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.

Pharmacology of estrogens and estrogen-induced effects on nonreproductive organs and systems

The classification of estrogens based on chemical structure and origin is presented. The metabolism of endogenous estrogens and the postulated mechanism of action of steroid hormones are reviewed. Specific effects of estrogen on bone, kidney and coagulation are also discussed.

Oral contraceptives and benign tumors of the liver

These discussions are selected from the weekly staff conferences in the Department of Medicine, University of California, San Francisco. Taken from transcriptions, they are prepared by Drs Homer A. Boushey, Associate Professor of Medicine, and David G. Warnock, Associate Professor of Medicine, under the direction of Dr Lloyd H. Smith, Jr, Professor of Medicine and Chairman of the Department of Medicine. Requests for reprints should be sent to the Department of Medicine, University of California, San Francisco, School of Medicine, San Francisco, CA 94143.

Estrogen replacement therapy: indications and complications

Estrogen replacement therapy is one of the most controversial issues in the field of reproductive medicine. Indications for its use include hot flashes, vaginal atrophy, and risk of osteoporosis. Risk of heart disease may also be an indication but this use has not been firmly established. The role of estrogen replacement therapy in aging changes of skin needs clarification. Complications of therapy include endometrial cancer, breast cancer, hypertension, hyperlipidemia, and gallbladder disease. The last three complications presumably result from hepatic actions of estrogen replacement therapy.

Interactions of oestrogens and hours of sleep on cortisol, FSH, LH, and prolactin in hypogonadal women

The effects of conjugated oestrogens 0.625 mg and placebo on adrenal and pituitary hormones were compared in 10 postmenopausal women during their sleep by means of double blind prospective crossover study. On placebo, the women had nocturnal variations in LH, prolactin and cortisol concentrations. However, oestrogen administration selectively blunted LH and prolactin changes, but not the rise in cortisol.

Estrogens and breast cancer: present position

Oestrogen is probably involved in breast cancer in two main ways: (1) in the aetiology of the disease as a promoting substance rather than as a carcinogen; (2) in stimulating the growth of at least some established breast cancers, acting through the oestrogen receptor. Successful modes of endocrine therapy would then be interpreted as interfering with (a) the supply of oestrogen to the tumour (b) the nuclear events in oestrogen action or (c) receptor replenishment.