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At least 253 records · Page 14Linked to original sources
PubMed1987

Pharmacokinetics of contraceptive steroids in patients with cystic fibrosis.

The pharmacokinetics of the commonly used contraceptive steroids ethinyloestradiol and levonorgestrel were investigated after oral and intravenous administration in six women with cystic fibrosis. The results were compared with data obtained from healthy women of similar age. The total body clearance of ethinyloestradiol was significantly higher in the patients with cystic fibrosis (0.61 (SD 0.19) l/h/kg) than in control women (0.32 (0.16) l/h/kg; p less than 0.02). In addition, the oral bioavailability of ethinyloestradiol was greater in women with cystic fibrosis than in controls (76.9% (11.7%) compared with 47.3% (7.5%); p less than 0.001). As a result of these two changes, the area under the plasma concentration--time curve after an oral dose of ethinyloestradiol was similar in patients and controls. The pharmacokinetics of levonorgestrel did not differ significantly between patients with cystic fibrosis and healthy women. The data suggest that women with cystic fibrosis will receive similar contraceptive protection from these steroids as do healthy women.

Adult↗
PubMed1991

Pharmacokinetics of levonorgestrel in 18 women after 1 month of treatment with a triphasic oral contraceptive.

A triphasic levonorgestrel (LNG)- and ethinylestradiol-containing oral contraceptive was administered to 18 women. Plasma samples were obtained throughout a treatment cycle just before drug administration and on the last treatment day (day 21), several plasma samples were collected from each individual up to 48 h postadministration. LNG was determined by radioimmunoassay in all plasma samples. In addition, the concentration of sex-hormone-binding globulin (SHBG) was determined in plasma samples collected from the same subjects during treatment, as well as during a pre- and a posttreatment cycle. During the treatment cycle, plasma levels of LNG determined just before drug administration increased and reached steady state at about day 16. This increase was due to an increased dose of LNG according to the triphasic dose regimen, a concomitantly ethinylestradiol-induced increase in SHBG and due to pharmacokinetic accumulation, since LNG had a terminal half-life of approximately 28.5 h and the dosing interval was 24 h. Steady-state levels and pharmacokinetic parameters of LNG determined on the last day of treatment were in good accordance with previously published results.

Adolescent↗
PubMed1984

Benzodiazepine drug-drug interactions commonly occurring in clinical practice.

Pharmacokinetic drug-drug interactions which involve currently available benzodiazepines may be classified into two major categories: interactions which affect benzodiazepine rate of absorption, and interactions which affect clearance and, therefore, elimination half-life. Ethanol is the prototype for absorptive interactions. Concurrent ethanol use and oral ingestion of benzodiazepine derivatives uniformly slows the rate but does not change the extent of benzodiazepine absorption. Interactions which affect benzodiazepine clearance affect only those derivatives which are oxidatively metabolized or cleared as a function of hepatic blood flow (high first-pass clearance). Conjugated benzodiazepines are not implicated in such interactions. Rifampin and chronic ethanol use induce benzodiazepine oxidation, while cimetidine, oral contraceptives, ethanol (acute ingestion), disulfiram, isoniazid, and propranolol inhibit benzodiazepine oxidation. In addition, ethanol, cimetidine and isoniazid decrease first-pass hepatic extraction of triazolam, enhancing its systemic availability and decreasing oral clearance. The pharmacokinetic consequence of induction of benzodiazepine oxidation is higher clearance and decreased steady-state concentrations during chronic dosing. Conversely, inhibition of benzodiazepine oxidation decreases clearance and increases steady-state benzodiazepine concentrations during chronic dosing. Because a correlation of benzodiazepine plasma concentration and pharmacological effect is not established, the pharmacodynamic consequences of these interactions are not currently well characterized.

Anti-Anxiety Agents↗
PubMed1998

Gabapentin does not interact with a contraceptive regimen of norethindrone acetate and ethinyl estradiol.

Anticonvulsants that induce hepatic metabolism increase clearance of oral contraceptive hormones and thereby cause contraceptive failure. Gabapentin is not metabolized in humans and has little liability for causing metabolic-based drug-drug interactions. In healthy women receiving 2.5 mg norethindrone acetate and 50 microg ethinyl estradiol daily for three consecutive menstrual cycles, concurrent gabapentin administration did not alter the steady-state pharmacokinetics of either hormone. Thus, gabapentin is unlikely to cause contraceptive failure.

Acetates↗
PubMed1983

Drug control of steroid metabolism by the hepatic endoplasmic reticulum.

In this review evidence is provided for the interaction between various drugs and steroid hormones in man and between drugs and progestogens in experimental animals. The mechanism by which these drug interactions occur are of fundamental biochemical and pharmacological interest. The importance of practical clinical considerations of drug-steroid interactions has also been discussed. In particular, considering the present tendency to lower the dose of progestogen and estrogen in most contraceptive preparations, any factor that reduces the bioavailability of the steroid hormones becomes very important. Other drugs and environmental chemicals may interact with these steroids and thereby diminish their efficacy. Clinical studies have reported that the most important interfering drugs are some anticonvulsants and antibiotics, and the antituberculosis compound rifampicin. Anticonvulsants and antituberculotics affect microsomal enzyme induction in the liver or interfere with enzyme systems in the gut wall. The action of antibiotics is connected with the pharmacokinetics of contraceptive steroids by an interaction with their enterohepatic circulation. Some environmental factors such as smoking, alcohol, and other dietary variations, and concurrent hepatic disease may modify the disposition of circulating endogenous steroids and exogenous contraceptive steroids. These effects may alter their response accordingly. In our studies drug treatments of rats reduced serum progesterone level irrespective of whether a potent inducer (phenobarbital, 4-methylcoumarin) or a hepatotoxin (carbon tetrachloride, coumarin, alpha-naphthylisothiocyanate) was administered. These treatments affected hepatic progesterone content. Phenobarbital and carbon tetrachloride reduced serum level, but the hepatic incorporation was enhanced by phenobarbital and reduced by carbon tetrachloride. The opposite actions were selective; phenobarbital raised the oxidative pathway of progesterone metabolism but did not modify the reductive pathway. This drug also enhanced progesterone 16 alpha-, 6 beta-, and 20 alpha-hydroxylase, but did not alter delta 4 - 5 alpha-reductase. In contrast, carbon tetrachloride inhibited hydroxylase and enhanced reductase activities. The effects of these test compounds on progesterone-metabolizing enzymes in isolated microsomes in vitro were similar to the in vivo results. It is concluded that the action of various drugs on serum and liver progesterone levels and metabolism is probably related to changes manifest in the function of the hepatic endoplasmic reticulum.

Animals↗
PubMed1987

Mineral deposits formation in bioactive IUD's.

Mineral organic deposits have been observed in inert IUDs. The authors studied the presence of these deposits in bioactive IUDs. Inert, progesterone, and copper-releasing IUDs were removed at 12,24, and 36 months postinsertion. When the devices were cut between their vertical (body) and horizontal (arms) branches, both parts were processed independently. After laxly bound organic material was eliminated, the devices were extracted at 60 degrees Celsius for 90 minutes with 3N HC1, and finally all undissolved material was dissolved in 1N NaOH. In each fraction, protein and inorganic ions were measured. Mineral organic deposits were formed in all types of IUDs. The deposits increased with time in utero in a characteristic device-dependent pattern. The deposits were essentially made of proteins, sodium, and calcium ions and were higher on the inert Lippes Loop D (7.0 +or- 2.4 mg proteins; 2.8 +or- 0.85 mg calcium, and 0.138 +or- 0.048 mg sodium/device); less in the copper IUD (5.7 +or- 1.36 mg proteins, 0.89 +or- 0.12 mg calcium, and 0.180 +or- 0.046 mg sodium/device at 24 months); and even less in the progesterone-releasing IUDs (1.6 +or- 1.3 mg protein, 0.235 +or- 0.028 mg calcium, and 0.262 +or- 0.063 mg sodium/device).

Calcium↗
PubMed1991

Changes in the plasma levels of proteins C and S in young women on low-dose oestrogen oral contraceptives.

The physiological importance of proteins C and S as natural anticoagulants is demonstrated by the increased risk of thromboembolic disease among subjects with hereditary deficiency of both proteins. In the present study the effects were evaluated of low-dose oestrogen oral contraceptives (OC) on the plasma levels of immunological protein S, as free (PS-f), and in reversible complex with C4b-binding protein as well as functional protein C (PC) in a homogeneous group of 20 young healthy women. The participants were randomly given either gestodene (75 micrograms) or desogestrel (150 micrograms) in combination with ethinyl oestradiol (30 micrograms). Blood samples were taken prior to the initiation of the treatment and at the end of the sixth 21-day treatment cycle. The mean concentration of both free and bound PS fell significantly, the decrease still being within the reference range. Conversely, the plasma values for PC rose to a statistically significant extent. There were no significant differences between the two OCs. Hypothetically, the changes in PS-f (active fraction) might be conducive to a procoagulant state, which the increased PC may compensate. The reverse effect of two OCs on the activity of the protein C-protein S anticoagulant system might suggest a different regulation of their synthesis.

Adult↗
PubMed1989

Glucose and insulin levels after six months of treatment with a triphasic oral contraceptive containing ethinyl estradiol and norethindrone.

A prospective study of carbohydrate metabolism was done on 33 women who used a triphasic oral contraceptive (OC) containing ethinyl estradiol and norethindrone for six months. A three-hour oral glucose tolerance test was administered before and after the OC usage, and both the blood glucose and insulin levels were determined. A significant decrease in the fasting glucose level was found with treatment. All other glucose values and insulin levels were unchanged.

Adult↗
PubMed1989

Clinicopathological problems of the local tissue effect of IUDs containing copper. III. Cytochemical study of the endometrial scrapings.

The clinicopathological problems of the tissue effect of copper-containing IUDs are discussed. In the third part of their series, authors present the cytochemical analysis of the endometrial scrapings. For the investigations, dithizone, salicylaldoxime, rubeanic acid as well as dimethylglyoxime were used. The reaction precipitate, the copper dithizone complex, could be visualized partly intracellularly and intramitochondrially and partly interstitially. The technical problems of copper demonstration are also dealt with.

Copper↗
PubMed1986

Antacid does not reduce the bioavailability of oral contraceptive steroids in women.

The bioavailability of contraceptive steroids was studied in 12 women who were given an antacid and a contraceptive pill simultaneously. They were given a single pill containing ethinyl estradiol (EE2) 30 micrograms in combination with either norethisterone (NET) acetate 1 mg (n = 6), or levonorgestrel (LNg) 150 micrograms, (n = 6). Blood samples were collected up to 24 hours. Four weeks later the same pill was administered along with a single tablet of antacid (magnesium trisilicate 0.5 g and dried aluminum hydroxide 0.25 g) and blood samples were collected as before. Serum levels of NET, LNg and EE2 were measured by radioimmunoassay. No effect of antacid administration on bioavailability of any contraceptive steroid was observed as judged by peak levels and areas under concentration-time curve (AUC). Incidentally, significantly higher serum concentrations of EE2 were observed when it was administered in combination with NET than with LNg. The possible reasons for this finding are discussed.

Adult↗