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Objective: The purpose of this study was to determine whether interactions between non-rifamycin antibiotics and hormonal contraceptives result in decreased effectiveness or increased toxicity of either therapy., Study Design: We searched MEDLINE, Embase, clinicaltrials.gov, and Cochrane libraries from database inception through June 2016. We included trials, cohort, case-control, and pharmacokinetic studies in any language that addressed pregnancy rates, pharmacodynamics, or pharmacokinetic outcomes when any hormonal contraceptive and non-rifamycin antibiotic were administered together vs apart. Of 7291 original records that were identified, 29 met criteria for inclusion., Study Appraisal and Synthesis Methods: Two authors independently assessed study quality and risk of bias using the United States Preventive Services Task Force evidence grading system. Findings were tabulated by drug class., Results: Study quality ranged from good to poor and addressed only oral contraceptive pills, emergency contraception pills, and the combined vaginal ring. Two studies demonstrated no difference in pregnancy rates in women who used oral contraceptives with and without non-rifamycin antibiotics. No differences in ovulation suppression or breakthrough bleeding were observed in any study that combined hormonal contraceptives with any antibiotic. No significant decreases in any progestin pharmacokinetic parameter occurred during co-administration with any antibiotic. Ethinyl estradiol area under the curve decreased when administered with dirithromycin, but no other drug., Conclusion: Evidence from clinical and pharmacokinetic outcomes studies does not support the existence of drug interactions between hormonal contraception and non-rifamycin antibiotics. Data are limited by low quantity and quality for some drug classes. Most women can expect no reduction in hormonal contraceptive effect with the concurrent use of non-rifamycin antibiotics., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: To provide guidelines for health care providers on the use of contraceptive methods to prevent pregnancy and on the promotion of healthy sexuality., Outcomes: Overall efficacy of cited contraceptive methods, assessing reduction in pregnancy rate, safety, and side effects; the effect of cited contraceptive methods on sexual health and general well-being; and the availability of cited contraceptive methods in Canada., Evidence: Medline and the Cochrane Database were searched for articles in English on subjects related to contraception, sexuality, and sexual health from January 1994 to December 2015 in order to update the Canadian Contraception Consensus published February-April 2004. Relevant Canadian government publications and position papers from appropriate health and family planning organizations were also reviewed., Values: The quality of the evidence is rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care. Recommendations for practice are ranked according to the method described in this report., Summary Statements: RECOMMENDATIONS., (Copyright © 2017 The Society of Obstetricians and Gynaecologists of Canada/La Société des obstétriciens et gynécologues du Canada. Published by Elsevier Inc. All rights reserved.)

Background: With dramatic improvements in life expectancy for cystic fibrosis (CF) patients, contraception for women with CF has become an important issue. There are theoretical concerns that hormonal contraceptive use among women with CF may impact disease severity or risk for other adverse health outcomes, including thrombosis and poor bone health, as well as concerns that malabsorption or altered drug metabolism might impact contraceptive effectiveness., Objective: To evaluate evidence on the safety and effectiveness of contraceptive methods among women with CF., Search Strategy: We searched the PubMed database for all articles published from database inception through October 2015., Selection Criteria: We included studies that examined measures of disease severity, other health outcomes or indicators of contraceptive effectiveness among women with CF initiating or continuing a contraceptive method., Results: Seven studies met our inclusion criteria. Three observational studies of fair to poor quality suggest that use of oral contraceptives (OCs) does not negatively impact CF disease severity, defined as changes in pulmonary function, number of exacerbations or need for intravenous antibiotics. Three small studies of poor quality reported on contraceptive failure among women with CF using combined hormonal contraceptives (combined OCs, patch or ring). One pregnancy was reported in a patch user out of 43 hormonal contraceptive users across all studies. One pharmacokinetic study reported that women with CF achieve steroid hormone plasma concentrations similar to healthy women after ingestion of combined OCs., Conclusions: Limited evidence suggests that hormonal contraceptive use does not negatively impact disease severity among women with CF and that hormonal contraceptive effectiveness is not impaired by CF. Studies were limited by small sample sizes and short duration of follow-up. No studies examined the effect of hormonal contraception on thrombosis or bone health among women with CF., (Published by Elsevier Inc.)

Objective: To examine whether the co-administration of hormonal contraceptives (HC) and psychotropic drugs commonly used to treat anxiety and/or depression results in safety or efficacy concerns for either drug., Methods: We searched PubMed and Cochrane libraries for clinical or pharmacokinetic (PK) studies that examined co-administration of any HC with psychotropic drugs [selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), oral benzodiazepines, bupropion, mirtazapine, trazadone, buspirone, hydroxyzine, monoamine oxidase inhibitors (MAOIs), or atypical antipsychotics] in reproductive aged women., Results: Of 555 articles identified, 22 articles (18 studies) met inclusion criteria. We identified 5 studies on SSRIs, four on TCAs, one on bupropion, three on atypical antipsychotics and five on oral benzodiazepines. No articles met inclusion criteria for SNRIs, mirtazapine, trazadone, buspirone, hydroxyzine or MAOIs. Overall, clinical studies did not demonstrate differences in unintended pregnancy rates when HCs were administered with and without psychotropic drugs or in psychotropic drug treatment outcomes when psychotropic drugs were administered with and without HCs. PK studies did not demonstrate changes in drug exposure related to contraceptive safety, contraceptive effectiveness or psychotropic drug effectiveness for most classes of psychotropic drugs. However, limited PK data raise concern for HCs increasing systemic exposure of amitriptyline and imipramine (both TCAs), theoretically posing safety concerns., Conclusion: Limited quality and quantity evidence on use of psychotropic drugs and HCs suggests low concern for clinically significant interactions, though no data exist specifically for non-oral formulations of HC. Given the high frequency of use for both HCs and psychotropic drugs among reproductive-age women in the US, this review highlights a need for further research in this area., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Despite several drawbacks, the Pearl Index continues to be the most widely used statistical measure of contraceptive failure. However, Pearl indices reported in studies of newer hormonal contraceptives appear to be increasing., Study Design: We searched PubMed and Medical Intelligence Solutions databases for prospective trials evaluating oral contraceptive (OC) efficacy to examine potential factors that could contribute to increasing Pearl indices., Results: Numerous potential factors were identified, including an increased rate of failures of newer OCs, deficiencies in methods of calculating contraceptive failure rates, differences in study design and changes in patient populations resulting in increased rates of contraceptive failures due to the inappropriate or inconsistent use of the method., Conclusions: The two most likely important contributors to the increase in Pearl indices are more frequent pregnancy testing with more sensitive tests and less adherent study populations. Because study populations appear to be increasingly representative of the likely actual users once the product is marketed, we can expect to see even higher failure rates in ongoing and future studies. This result poses challenges for companies and regulatory agencies., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Background: This study analyzes levels of progesterone, estradiol, norethindrone (NET) and ethinyl estradiol (EE) in serum and levels of NET in cervical mucus on the last day of the hormone-free interval (HFI) in users of 24/4 [norethindrone acetate (NETA)/EE-24] vs. 21/7 (NETA/EE-21) regimens., Study Design: This was a randomized controlled, crossover, equivalency trial. Subjects were randomized to receive NETA/EE-24 or NETA/EE-21 for 2 months and then switched between study drugs. Blood and cervical mucus samples were obtained on Days 12-16 and on the last day of the HFI., Results: From April 2010 to November 2011, 32 subjects were enrolled with 18 subjects completing all study visits. There were no statistically significant differences in either day 12-16 (p=.54) or last hormone-free day (p=.33) cervical mucus NET concentrations between the regimens. On the last day of the HFI, median serum progesterone levels did not differ significantly; however, users of NETA/EE-24 had higher levels of serum NET (p<.001) and users of NETA/EE-21 had higher levels of serum estradiol (p=.01)., Conclusion: This data supports the fact that inhibition of the pituitary-ovarian axis occurs during oral contraceptive use and during the HFI. We demonstrated that a reduced HFI of 4 days resulted in better suppression of the ovarian hormone production, thereby reducing the risk of ovulation and potential contraceptive failure., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Background: We evaluated the effects of cytochrome P450 3A4 (CYP3A4) induction and inhibition on steady-state pharmacokinetics of the components of a novel oral contraceptive (OC) containing estradiol valerate (E₂V) and dienogest (DNG)., Study Design: CYP3A4 induction was assessed in an open-label, one-arm study. Sixteen healthy postmenopausal women received E₂V 2 mg/DNG 3 mg (days 1-17) and concomitant rifampicin (600 mg, days 12-16). Ratios of the area under the serum concentration-time curve between 0 and 24 h [AUC(0-24 h)] and maximum serum concentration (C(max)) of E₂ and DNG on days 17 and 11 (after and before rifampicin intervention) are presented. CYP3A4 inhibition was investigated in an open-label, parallel-group study in 24 healthy postmenopausal women receiving E₂V 2 mg/DNG 3 mg (days 1-14) and concomitant ketoconazole (400 mg, n=12) or erythromycin (500 mg three times daily, n=12) on days 8-14. Mean ratios of AUC(0-24 h) and C(max) of E₂ and DNG on days 7 and 14 are presented., Results: Concomitant administration of rifampicin decreased systemic drug exposure and yielded geometric mean ratios for E₂C(max) and AUC(0-24 h) of 75% and 56%, respectively. Corresponding mean ratios for DNG were 48% and 17%, respectively. Ketoconazole coadministration increased systemic drug exposure and yielded ratios of E₂ of 165% and 157%, respectively, and ratios of DNG of 194% and 286%, respectively. Erythromycin coadministration also resulted in increased mean C(max) and AUC(0-24 h) of both E₂ and DNG. Geometric mean ratios of C(max) and AUC(0-24 h) for E₂ were 151% and 133%, respectively. Corresponding ratios for DNG were 133% and 162%, respectively., Conclusions: Significant drug-drug interactions are apparent when CYP3A4 modulators are coadministered with the components of a novel OC containing E₂V/DNG. Coadministration of CYP3A4 modulators should be avoided where possible, and another type of contraception should be used when coadministration of CYP3A4 inducers like rifampicin is unavoidable., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Many guidelines regarding the daily management of regular oral hormonal contraceptive methods have been proposed worldwide. Some of them may even appear to be conflicting. The search for the maximal contraceptive protection leads to a low acceptance of these guidelines, probably because of their complexity and their apparent discrepancy. We are deeply convinced that simplicity and pragmatism of guidelines should pave the way to both their better acceptance and compliance and, consequently, to their improved real-life effectiveness. We have considered physiology and pharmacodynamics before proposing the following rules for an effective management of hormonal contraceptive failures. We conclude that the risk of unwanted pregnancy is higher in case of a unique contraception misuse/a delayed start during the first week of the contraceptive cycle (or in case of multiple days of contraceptive misuses during the following weeks) for a combined contraception or at every cycle day for a non anti-ovulatory progestin only contraception. In such risky situations, we firmly recommend the restart of the regular contraceptive method and the use of condoms for the following 72 hours, provided no sexual intercourse has occurred during the past 5 days before the contraceptive failure. If sexual intercourse has occurred during the past 5 days before the contraceptive failure, we firmly recommend the intake of an emergency contraception, ulipristal acetate, the restart the regular contraceptive method and in this case, the use of condoms for, at least, the following 7 days., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

The effect of obesity on drug metabolism and pharmacokinetics is poorly understood, and this is particularly true in regard to contraceptive steroids. This article will review the known and theoretical physiologic and pharmacologic interactions between obesity and contraceptive steroids., (Copyright © 2010 Elsevier Inc. All rights reserved.)

The purpose of this study was to develop smart polymer based controlled delivery systems to deliver steroidal hormones after single subcutaneous (s.c.) injection at predetermined rates over extended period of time. In vivo absorption and pharmacokinetics of levonorgestrel (LNG) and testosterone (TSN) were investigated from the thermosensitive and phase sensitive polymeric controlled delivery systems. A selective, reliable, and rapid method for determination of serum LNG concentration was developed using high-performance liquid chromatography-tandom mass spectrometry with atmospheric pressure chemical ionization interface (HPLC-MS-MS with APCI), while TSN in serum samples was detected and quantified by a competitive immunoassay. The delivery systems controlled the absorption of LNG in rabbits up to 6 weeks from thermosensitive and approximately 4 weeks from phase sensitive polymeric delivery systems. In vivo study of TSN delivery systems in castrated rabbits controlled the release of TSN for at least 2 months from both thermosensitive and phase sensitive polymers. Thermosensitive and phase sensitive polymer formulations significantly (p < 0.05) increased relative bioavailability of steroidal hormones compared to control. In conclusion, thermosensitive and phase sensitive polymer based delivery systems controlled the release in vivo in rabbits for longer duration after single s.c. injection., ((c) 2010 Wiley-Liss, Inc. and the American Pharmacists Association)

Nearly 50 years ago, the introduction of Enovid (norethynodrel 10 microg and mestranol 150 microg), which provided convenient and reliable contraception, revolutionized birth control. Reports of interactions between oral contraceptives (OCs) and other drugs began to trickle into the literature. At first, these drug interactions appeared to be random and unrelated. Increased understanding of P450 enzymes and phase II reactions of sulfation and glucuronidation has permitted preliminary categorization and assessment of the clinical relevance of these drug interactions.

Two semi-automated, relatively high throughput methods using ultra performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) were developed for the simultaneous determination of ethinyl estradiol (EE) in combination with either 19-norethindrone (NE) or levonorgestrel (LN) in human plasma. Using 300 microL plasma, the methods were validated over the concentration ranges of 0.01-2 ng/mL and 0.1-20 ng/mL for EE and NE (or LN), respectively. The existing methods for the determination of the oral contraceptives in human plasma require large volumes of plasma (> or =500 microL), and sample extraction is labor-intensive. The LC run time is at least 6 min, enabling analysis of only about 100 samples a day. In the present work the throughput was greatly improved by employing a semi-automated sample preparation process involving liquid-liquid extraction and derivatization with dansyl chloride followed by UPLC separation on a small particle size column achieving a run time of 2.7 min. The validation and actual sample analysis results show that both methods are rugged, precise, accurate, and well suitable to support pharmacokinetic studies where approximately 300 samples can be extracted and analyzed in a day.

This open-label, randomized study compared the pharmacokinetics of ethinylestradiol (EE) from the contraceptive vaginal ring NuvaRing (15 microg EE/day), the transdermal patch (20 microg EE/day) and a combined oral contraceptive (COC) containing 30 microg EE. After 2-8 weeks of synchronization by COC treatment, subjects were randomized to 21 days of treatment with NuvaRing, patch or COC. Analysis of area under the EE concentration-versus-time curve (AUC) during 21 days of treatment showed that exposure to EE in the NuvaRing group was 3.4 times lower than in the patch group (p < .05) and 2.1 times lower than in the pill group (p < .05). Serum EE levels of subjects showed much lower variation with NuvaRing than with the patch or the COC. Thus, exposure to EE was significantly lower with NuvaRing than with the patch and pill methods, demonstrating that NuvaRing is a low-estrogen-dose contraceptive method that also results in low estrogen exposure.

Presently, the lowest effective estrogen dose available as a combination oral contraceptive (OC) in the United States is 20 microg of ethinyl estradiol (EE) with different progestins. Twenty micrograms of EE coupled with levonorgestrel results in fewer side effects and cycle control comparable with higher-dose pills. Differences between therapeutically equivalent and brand-name, low-dose oral contraceptives, with respect to the bioavailability of hormones, may interfere with contraceptive efficacy and increase breakthrough bleeding. One of the most common reasons why women discontinue OCs is increased breakthrough bleeding. Because after OC discontinuation most women switch to a less-effective method, or no method, of contraception, an increase in breakthrough bleeding could ultimately result in an increase in unintended pregnancy. Thus, substituting a therapeutically equivalent for a brand-name low-dose oral contraceptive may have significant clinical and economic effects on individual and public health.

Written guidelines for the preclinical testing of contraceptive steroids have not been revised since 1968 despite the fact that many important changes have been implemented by the FDA's Division of Metabolism and Endocrine Drug Products. This paper describes the new preclinical testing requirements and the rationale for their implementation.

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 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.

Serum levels of 3-ketodesogestrel and ethinyl estradiol were analyzed by radioimmunoassay in a balanced crossover study with two tablet formulations containing desogestrel (0.150 mg) and ethinyl estradiol (0.030 mg) in 25 women under steady-state conditions after 21 days of treatment. The pharmacokinetic properties of desogestrel were characterized by the following parameters: (1) maximum serum concentration, (2) time to maximum serum concentration, (3) total area under the serum concentration versus time curve, and (4) serum half-life of elimination. The interindividual variation in these parameters was comparable with that observed with other contraceptive combinations containing ethinyl estradiol and norethisterone, levonorgestrel, or gestodene. The serum distribution of contraceptive progestogens is known to be determined by their affinity to sex hormone-binding globulin and the concentration of sex hormone-binding globulin. We analyzed the structural features that determine binding to sex hormone-binding globulin. The 18-methyl group increased and the 11-methylene group weakened the binding to sex hormone-binding globulin. The double bond at C-15 reinforced the binding only when combined with an 18-methyl group. Therefore, the binding of levonorgestrel (the 18-methyl derivative of norethisterone) and gestodene (the delta-15,18 methyl derivative of norethisterone) to sex hormone-binding globulin was much stronger than that of 3-keto-desogestrel and norethisterone.

Oral contraceptive steroids may undergo enterohepatic circulation, but it is relevant for only estrogens, because these compounds can be directly conjugated in the liver. Animal studies show convincing evidence of the importance of the enterohepatic circulation, but studies in humans are much less convincing. The importance of the route and the rate of metabolism of ethinyl estradiol are reviewed. Some antibiotics have been reported anecdotally to reduce the efficacy of oral contraceptive steroids, but controlled studies have not confirmed this observation. Although gut flora are altered by oral antibiotics, the blood levels of ethinyl estradiol are not reduced, and one antibiotic at least (cotrimoxazole) enhances the activity of ethinyl estradiol.

A number of oral contraceptive steroids undergo first-pass metabolism in the gastrointestinal mucosa. Ethinyl estradiol (mean systemic bioavailability 40% to 50%) is extensively metabolized, principally to a sulfate conjugate. In vivo studies that use portal vein catheterization and the administration of radiolabeled ethinyl estradiol have shown that the fraction of steroid metabolized in the gut wall is 0.44. In vitro studies with jejunal biopsy samples or larger pieces of jejunum or terminal ileum mounted in Ussing chambers have indicated that more than 30% of added ethinyl estradiol is sulfated. The progestogen desogestrel is a prodrug that is converted to the active metabolite 3-ketodesogestrel. Substantial first-pass metabolism of desogestrel occurs in the gut mucosa, with evidence from Ussing chamber studies for the formation of the active metabolite. Another progestogen, norgestimate, is also metabolized by the gut wall in vitro of which the principal metabolite is the deacetylated product, norgestrel oxime. It seems very likely that this will also occur in vivo. Drug interactions occurring in the gut wall have been reported with ascorbic acid (vitamin C) and paracetamol.

The time-dependent alterations in the serum concentrations of ethinyl estradiol, gestodene, and 3-keto-desogestrel during treatment with 30 micrograms of ethinyl estradiol + 75 micrograms of gestodene or 30 micrograms of ethinyl estradiol + 150 micrograms of desogestrel were investigated during 12 months. The levels of gestodene and 3-keto-desogestrel increased between days 1 and 21 of each cycle, reaching maximal levels during the third and sixth cycles. The serum concentrations of gestodene were fourfold to fivefold higher than those of 3-keto-desogestrel. The ethinyl estradiol levels increased significantly between days 1 and 10 during each cycle and were significantly higher by 70% during intake of ethinyl estradiol/gestodene compared with ethinyl estradiol/desogestrel, although the dose was identical. Intake of gestodene, in addition to 35 micrograms of ethinyl estradiol + 2 mg of cyproterone acetate, caused a rise in ethinyl estradiol levels. During treatment with ethinyl estradiol/gestodene and an additional 150 micrograms of levonorgestrel, there was a continuous increase in gestodene levels, although sex hormone-binding globulin level did not change. During treatment with 30 or 35 micrograms of ethinyl estradiol and 75 micrograms of gestodene, 150 micrograms of desogestrel, or 2 mg of cyproterone acetate, there were large intraindividual and interindividual variations in the steroid levels and ratios of estrogen: progestogen levels. There was no correlation with the occurrence of intermenstrual bleedings. It is concluded that ethinyl estradiol and nortestosterone derivatives may inhibit steroid-metabolizing enzymes in the liver, which results in a rise in the serum levels of contraceptive steroids. The cause of the large intraindividual variations is as yet unknown, but it is probably from changes in steroid metabolism.

Our knowledge of the peculiarities of prohormones is rather limited, both pharmacologically and clinically. Generalizations cannot be made except that the lapse of time until peak blood values of the active drug have been reached are always greater after intake of the prodrug than after intake of the drug. This finding is presumably of no clinical importance. If pharmacokinetic differences are limited to the phase of distribution, bioequivalence may be assumed. If, on the other hand, the area under the curve during the elimination phase is smaller for the prodrug than for the drug, the potency of the former should be decreased. A shift in the spectrum of endocrine actions as a result of the biotransformation of the prodrug into the active drug is rather the exception than the rule, and so is a change in side effects. If there are major differences in this respect, metabolic pathways in addition to those leading to the respective active drug must also be taken into consideration.

Results from two clinical pharmacokinetic studies are given. The first study was an observational study in oral contraceptive users who took either a combination of gestodene and ethinyl estradiol (pill A, Femovan) or desogestrel and ethinyl estradiol (pill B, Marvelon). A total of 69 women (39 receiving pill A and 30 receiving pill B) were evaluated to determine serum ethinyl estradiol, sex hormone-binding globulin, corticosteroid-binding globulin, and cortisol levels. Samples were obtained on 1 day during the tenth to twenty-first days of pill intake. All women received the respective oral contraceptive for at least 3 months. The test power was such that an 80% difference of 1 standard deviation of each target variable would have been detected (alpha = 0.05; beta = 0.1). No statistically significant differences were found in sex hormone-binding globulin, corticosteroid-binding globulin, or cortisol serum levels between both groups. Time and height of maximum ethinyl estradiol levels were identical as was the area under the curves. Ex vivo protein-binding analysis of the progestins revealed a free portion of 0.6% for gestodene and 2.5% for 3-ketodesogestrel as the active metabolite of desogestrel. Sex hormone-binding globulin-bound portions were much higher for gestodene (75.3% +/- 9.1%) than for 3-ketodesogestrel (31.6% +/- 12%). The remaining fractions were bound to albumin. In a second study, ethinyl estradiol-bioequivalence from pills A and B was investigated in 18 women in a controlled, single-dose, randomized, crossover design. The area under the ethinyl estradiol serum levels were identical up to 4 hours after pill intake between both treatments. According to the relatively low variation in data in this group of women, a 10% difference in ethinyl estradiol-availability could have been detected. Both studies indicate that the pharmacokinetics of ethinyl estradiol were independent of the concomitantly administered progestin, that is, desogestel and gestodene.

A radioimmunoassay for the determination of gestodene (17-ethinyl-13-ethyl-17 beta-hydroxy-4,15-gonadien-3-one) in human plasma is described with regard to procedure, specificity, accuracy and reproducibility. Antiserum was raised against gestodene-3-O-(carboxymethyl)oxime-BSA in rabbits and [9,11-3H]-gestodene tracer was used with a specific radioactivity of 2.16 TBq/mmol. The final antiserum dilution was 1: 200,000. RIA was performed according to routine methods using diethylether plasma extracts and the charcoal separation technique. Cross-reactivity of antiserum with cortisol, 17 beta-estradiol, progesterone, testosterone and ethinylestradiol was less than 0.03%; levonorgestrel exhibited a 5% cross-reactivity. No cross-reactivity with metabolites of gestodene or ethinylestradiol was found. Accuracy and precision of the assay were tested using human plasma samples spiked with 1, 5 and 10 ng/ml gestodene. Accuracy was within 94 to 104% of the nominal values. Within-assay and between-assay coefficients of variation were in the range of 4.7-6.5% and 10.3-13.1%, resp. This RIA was used to follow plasma gestodene levels after single oral administration of 75 micrograms of gestodene combined with 30 micrograms ethinylestradiol as tablet and coated tablet in a cross-over design in 6 female test subjects. Plasma gestodene levels were equivalent after both treatments.

Serial studies were conducted in five women under norgestrel + EE-2 after interrupting 11-34 months of regular use of the medication. A venous blood and an endometrial sample were simultaneously obtained from each subject between the 22nd and 25th day of the pseudocycle (last month of contraception) and on the same days of the following three cycles under no treatment for the measurement of EE-2 content. Values during and after the first month of no medication were: plasma = 85 +/- 6 versus 218 +/- 36 (pg/ml; P less than 0.001) and endometrium = 93 +/- 10 versus 29 +/- 7 (ng/g wet tissue; P less than 0.001). A decrement of circulating EE-2 from 346 pg/ml in the first month with no medication to 14 pg/ml in the third month off the treatment was observed. The EE-2 endometrial uptake of 93 +/- 10 (last month of steroidal ingestion) decreased to 29 +/- 7, 7 +/- 2 and 4 +/- 0.9 ng/g wet tissue in the following three months of no treatment. In 3/15 instances after interrupting contraception, circulating EE-2 was below the detection limit of the assay, while endometrial EE-2 uptake was in the range of 3-19 ng/g wet tissue. These data confirm our apparent controversial report that EE-2 plasma levels increased during the first month after interrupting medication and support the presence of the exogenous estrogen in plasma and endometrium after interrupting the steroidal contraceptive for three months.

The serum concentrations of ethinylestradiol (EE) during the first 4 h and 24 h after intake of an oral contraceptive containing 30 micrograms EE and 75 micrograms gestodene (EE/GSD) were compared to those after intake of a preparation containing the same EE dose and 150 micrograms desogestrel (EE/DG) in each of 11 women on days 1, 10, and 21 of their 1st, 3rd, 6th, and 12th cycles. There were great interindividual variations, but during treatment with EE/GSD the EE levels were higher and the EE peaks occurred by 30 min later than during treatment with EE/DG. The areas under the EE serum concentration-versus-time curves (AUC) between 0 and 4 h were higher by 37% (p less than 0.03) and between 0 and 24 h higher by 70% (p less than 0.002) during treatment with EE/GSD. During each treatment cycle, the EE levels rose between day 1 and 10. The serum levels of corticosteroid-binding globulin (CBG), which is known to be influenced only by the estrogenic component of the combination pill, increased significantly (p less than 0.01) during each treatment cycle. CBG was elevated on day 21 of the 6th and 12th cycle by 150 to 155% and by 120 to 130% with EE/GSD and EE/DG, respectively. The difference between the two drugs was significant (p less than 0.02). During the pill-free intervals of 7 days between the treatment cycles, the CBG levels decreased but were still elevated by 85% with EE/GSD and 50% with EE/DG at the beginning of the following cycle as compared to the control cycle. The serum levels of cortisol were also significantly more elevated (p less than 0.05) during treatment with EE/GSD as compared to EE/DG. Despite the same EE dose during treatment, the higher EE levels with EE/GSD as compared to EE/DG seem to be due to a retardation of the inactivation and elimination of EE caused by the progestogen component. The rise in the EE levels during each cycle seems to be due to a reduction in the oxidative metabolism by EE itself.

We have examined the pharmacokinetic parameters derived from the analysis of plasma ethinyl estradiol (EE) and norethindrone levels after administration of a single dose of three bioequivalent norethindrone-1mg/mestranol (ME)-50 micrograms formulations (Ortho-NovumR 1/50, NorinylR 1/50 and Norcept-MR 1/50) and three norethindrone-1mg/ethinyl estradiol-35 micrograms formulations (Ortho-Novum 1/35R, NorinylR 1/35, Norcept-ER 1/35) in a randomized crossover design involving 24 women for the 35 micrograms and 27 women for the 50 micrograms agents. Differences between the AUC-EE of pairs from the same manufacturer (1 + 35 and 1 + 50) were not significantly different, indicating that 50 micrograms of mestranol was equivalent to 35 micrograms ethinyl estradiol with respect to this pharmacokinetic parameter. The Cmax values were also similar. Inter-individual coefficients of variation (C.V.) for the AUC-EE were 47% and 57% for the 1 + 35 and 1 + 50 agents, respectively. Intra-individual C.V.s were 41% and 42%, respectively. For norethindrone, the AUC was larger with the 1 + 50 formulations than with the 1 + 35 group (87.9 vs. 72.8 pg hr/ml). Additionally, the Cmax values were larger for the 1/50 group (17.7 vs. 14.0). Since the amount of norethindrone in the two dosage groups was the same, this difference in the pharmacokinetics between the 35 micrograms EE and the 50 micrograms ME formulations remains unexplained. The inter-individual C.V. averaged 56% for both dosage groups. The intra-individual C.V.s were 17% and 46% for the 1 + 35 and 1 + 50 groups, respectively. The large variation in blood levels of ethinyl estradiol and norethindrone between and within individuals may overshadow clinical differences attributable to differences in dosage.