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J Trussell - One of the best experts on this subject based on the ideXlab platform.
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Short communication Minimum effectiveness of the levonorgestrel Regimen of emergency contraception
2004Co-Authors: Elizabeth G Raymond, J Trussell, Douglas J. Taylor, Markus J. SteinerAbstract:The standard method for estimating the effectiveness of emergency contraceptive pills (ECPs) uses external data to calculate the proportion of expected pregnancies averted by the treatment. Because these data may not be applicable to ECP study populations, this approach could result in substantial overestimation of effectiveness. We used data from two published randomized trials of the levonorgestrel and Yuzpe ECP Regimens to calculate the minimum effectiveness of the levonorgestrel Regimen. Conservatively assuming that the Yuzpe Regimen was entirely ineffective in these trials, we estimate that the levonorgestrel Regimen prevented at least 49% of expected pregnancies (95% confidence interval: 17%, 69%). Because physiologic data suggests that the Yuzpe Regimen does, in fact, have some efficacy, the effectiveness of the levonorgestrel Regimen is likely to be higher than our minimum estimate. © 2004 Elsevier Inc. All rights reserved.
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Minimum effectiveness of the levonorgestrel Regimen of emergency contraception
Contraception, 2004Co-Authors: Elizabeth G Raymond, J Trussell, Douglas J. Taylor, Markus J. SteinerAbstract:The standard method for estimating the effectiveness of emergency contraceptive pills (ECPs) uses external data to calculate the proportion of expected pregnancies averted by the treatment. Because these data may not be applicable to ECP study populations, this approach could result in substantial overestimation of effectiveness. We used data from two published randomized trials of the levonorgestrel and Yuzpe ECP Regimens to calculate the minimum effectiveness of the levonorgestrel Regimen. Conservatively assuming that the Yuzpe Regimen was entirely ineffective in these trials, we estimate that the levonorgestrel Regimen prevented at least 49% of expected pregnancies (95% confidence interval: 17%, 69%). Because physiologic data suggests that the Yuzpe Regimen does, in fact, have some efficacy, the effectiveness of the levonorgestrel Regimen is likely to be higher than our minimum estimate.
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Extending the time limit for starting the Yuzpe Regimen of emergency contraception to 120 hours.
Obstetrics and gynecology, 2003Co-Authors: Charlotte Ellertson, Margaret Evans, Sue Ferden, Clare Leadbetter, Aileen Spears, Karen Johnstone, J TrussellAbstract:Abstract Objective Current protocols state that the Yuzpe Regimen of emergency contraception can be initiated up to 72 hours after unprotected intercourse. The purpose of this study was to determine whether the window for emergency hormonal contraception can be extended to 120 hours. Methods In an observational study, we tracked 111 women who requested emergency contraception between 72 and 120 hours after unprotected sex but refused postcoital copper intrauterine devices (IUDs), preferring instead the Yuzpe Regimen. We compared failure rates for this group with rates among 675 otherwise similar women who started the same therapy within 72 hours. Results Both perfect use (1.9%) and typical use (3.6%) failure rates were low among women presenting between 72 and 120 hours after unprotected intercourse. These rates did not statistically differ from failure rates for the standard Yuzpe Regimen (2.0% during perfect use and 2.5% during typical use). Our small sample size of 111, however, gave us just 25% power to detect a doubling in the failure rates (2% to 4%) and 59% power to detect a tripling in the failure rates (2% to 6%). Conclusion The 72-hour cutoff for the Yuzpe Regimen of emergency contraception appears needlessly restrictive. Women who request this therapy more than 72 hours after unprotected sex should be allowed to receive it, particularly if they decline postcoital insertion of a copper IUD and would otherwise have no options for reducing pregnancy risk.
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Extending the time limit for starting the Yuzpe Regimen of emergency contraception to 120 hours
Obstetrical & Gynecological Survey, 2003Co-Authors: Charlotte Ellertson, Margaret Evans, Sue Ferden, Aileen Spears, Karen Johnstone, Clare Ledbetter, J TrussellAbstract:In conjunction with a study of modifications to the Yuzpe Regimen of emergency contraception delivered with 72 hours of unprotected intercourse, the authors conducted a second prospective trial that investigated the efficacy of the Regimen beyond 72 hours. Both trials accepted women aged 16-45 years (in the United States, 18-45 years) with regular menstrual cycles who had unprotected intercourse between 10 days before and 6 days after expected ovulation and who refused a copper intrauterine device. Participants had to be willing to abstain from unprotected intercourse during the study cycle and willing to return for a follow-up visit. The Yuzpe Regimen used consisted of 100 μg of ethanol estradiol plus 1.0 mg of norgestrel repeated after 12 hours. Study patients were women who presented 4-5 days after unprotected intercourse (n = 111); women enrolled in the first trial served as control subjects (n = 675). Overall, 3.7% (4 of 111) of women treated in the extended time period became pregnant compared with 2.5% of control subjects (17 of 675), but the difference was not significant. It was determined that 2 (1.9%) study patients and 12 (2.5%) patients in the control group had followed the Regimen perfectly. Women who strayed from the prescribed standard 2-dose Regimen were considered typical users. Perfect use of the Regimen within 1-3 days prevented 77% expected pregnancies in women who received no intervening therapy after unprotected intercourse, and perfect use within 3-4 days prevented 73% of expected pregnancies.
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Effectiveness of the Yuzpe Regimen of emergency contraception by cycle day of intercourse: implications for mechanism of action.
Contraception, 2003Co-Authors: J Trussell, Charlotte Ellertson, Laneta DorflingerAbstract:Abstract Objective The purpose of this study was to provide evidence about the mechanism of action of the Yuzpe method of emergency contraception by examining effectiveness by cycle day of intercourse relative to ovulation. Methods Through a literature search, we identified eight studies that present the number of women treated and outcome of treatment by cycle day of unprotected intercourse relative to expected day of ovulation. Using five sets of external estimates of conception probabilities by cycle day of intercourse among women not using contraception, we assessed and compared the effectiveness of the Yuzpe Regimen by whether intercourse occurred on or before the second day before ovulation or afterward, and whether intercourse occurred on or before the first day before ovulation or afterward. Results In 36 of the 45 pairs of estimates of effectiveness, based on eight separate studies and the eight studies combined and five different sets of conception probabilities by cycle day, effectiveness was higher—and in most cases substantially higher—when intercourse occurred on or before the second day before ovulation (day −2) than when it occurred later. When data were stratified by whether intercourse occurred on or before the day before ovulation (day −1), effectiveness was greater when intercourse occurred early in 43 of 45 pairs. Conclusions These results suggest that one hypothesized mechanism of action of the Yuzpe method, inhibiting implantation of a fertilized egg, is unlikely to be the primary mechanism of action.
Elizabeth G Raymond - One of the best experts on this subject based on the ideXlab platform.
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Short communication Minimum effectiveness of the levonorgestrel Regimen of emergency contraception
2004Co-Authors: Elizabeth G Raymond, J Trussell, Douglas J. Taylor, Markus J. SteinerAbstract:The standard method for estimating the effectiveness of emergency contraceptive pills (ECPs) uses external data to calculate the proportion of expected pregnancies averted by the treatment. Because these data may not be applicable to ECP study populations, this approach could result in substantial overestimation of effectiveness. We used data from two published randomized trials of the levonorgestrel and Yuzpe ECP Regimens to calculate the minimum effectiveness of the levonorgestrel Regimen. Conservatively assuming that the Yuzpe Regimen was entirely ineffective in these trials, we estimate that the levonorgestrel Regimen prevented at least 49% of expected pregnancies (95% confidence interval: 17%, 69%). Because physiologic data suggests that the Yuzpe Regimen does, in fact, have some efficacy, the effectiveness of the levonorgestrel Regimen is likely to be higher than our minimum estimate. © 2004 Elsevier Inc. All rights reserved.
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Minimum effectiveness of the levonorgestrel Regimen of emergency contraception
Contraception, 2004Co-Authors: Elizabeth G Raymond, J Trussell, Douglas J. Taylor, Markus J. SteinerAbstract:The standard method for estimating the effectiveness of emergency contraceptive pills (ECPs) uses external data to calculate the proportion of expected pregnancies averted by the treatment. Because these data may not be applicable to ECP study populations, this approach could result in substantial overestimation of effectiveness. We used data from two published randomized trials of the levonorgestrel and Yuzpe ECP Regimens to calculate the minimum effectiveness of the levonorgestrel Regimen. Conservatively assuming that the Yuzpe Regimen was entirely ineffective in these trials, we estimate that the levonorgestrel Regimen prevented at least 49% of expected pregnancies (95% confidence interval: 17%, 69%). Because physiologic data suggests that the Yuzpe Regimen does, in fact, have some efficacy, the effectiveness of the levonorgestrel Regimen is likely to be higher than our minimum estimate.
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Emergency contraception.
Annals of Internal Medicine, 2002Co-Authors: David A Grimes, Elizabeth G RaymondAbstract:Emergency contraception is used to prevent pregnancy after a coital act not adequately protected by a regular method of contraception. In contrast to early medical abortion, emergency contraception prevents a pregnancy from starting and does not disrupt an established pregnancy. The most commonly used approaches consist of two oral doses of contraceptive steroids. The levonorgestrel-only Regimen (levonorgestrel, 0.75 mg, repeated in 12 hours) appears to be more effective and better tolerated than the Yuzpe Regimen (ethinyl estradiol, 100 microg, and levonorgestrel, 0.5 mg, repeated in 12 hours). In the largest randomized, controlled trial to date, levonorgestrel prevented about 85% of pregnancies that would have occurred without its use. Hormonal emergency contraception has no known medical contraindications, although it is not indicated for suspected or confirmed pregnancy. However, if hormonal emergency contraception is inadvertently taken in early pregnancy, neither the woman nor the fetus will be harmed. Nausea and vomiting associated with the Yuzpe Regimen can be reduced by prophylactic use of meclizine. A strong medical and legal case exists for making hormonal emergency contraception available over the counter, as has happened in countries other than the United States. Easier access to and wider use of emergency contraception could dramatically lower the high rates of unintended pregnancy and induced abortion in the United States.
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Effect of the Yuzpe Regimen of emergency contraception on markers of endometrial receptivity
Human reproduction (Oxford England), 2000Co-Authors: Elizabeth G Raymond, Laurie P. Lovely, Mario Chen-mok, Markku Seppälä, Robert J. Kurman, Bruce A. LesseyAbstract:This exploratory study was designed to determine whether treatment with the Yuzpe Regimen of emergency contraception altered endometrial integrin expression or other markers of uterine receptivity. Nineteen parous women were followed for two menstrual cycles. In the second cycle, each participant took 100 mg ethinyl oestradiol and 1 mg norgestrel on the day of the urinary luteinizing hormone (LH) surge and repeated the dose 12 h later. In both cycles, endometrial biopsy, phlebotomy and vaginal sonogram were performed 8-10 days after the urinary LH surge. No significant difference was found between untreated and treated cycles in most measures of endometrial histology or in endometrial expression of beta3 integrin subunit, leukaemia inhibitory factor, glycodelin, or progesterone receptors assessed by immunohistochemical techniques. Five statistically significant changes were noted in treated cycles: a reduction in endometrial MUC-1 expression, an increase in endometrial oestrogen receptor, lower luteal phase serum oestrogen concentration, reduced endometrial thickness, and greater proportion of glandular supranuclear vacuoles. The relationship of these findings to the contraceptive action of the Yuzpe Regimen is unclear.
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Meclizine for prevention of nausea associated with use of emergency contraceptive pills: a randomized trial.
Obstetrics and gynecology, 2000Co-Authors: Elizabeth G Raymond, Mitchell D. Creinin, Kurt T. Barnhart, Amy E Lovvorn, R Wesley Rountree, J TrussellAbstract:Objective: We conducted a randomized trial to determine whether pretreatment with meclizine reduces the incidence of nausea and vomiting associated with the Yuzpe Regimen of emergency contraception. Methods: We randomly assigned 343 women aged 18–45 years who were not at risk for pregnancy to pretreatment with 50 mg of meclizine, placebo, or no drug 1 hour before the first of two doses of emergency contraceptive pills. We asked participants to complete three questionnaires over the following 48 hours. Results: The incidence of nausea was 47% in the group pretreated with meclizine and 64% in the other two groups (relative risk adjusted for center 0.7, 95% confidence intervals 0.6, 0.9 for comparisons of meclizine with both placebo and no drug). The severity of nausea and the incidence of vomiting were also significantly lower in the meclizine pretreatment group than in the other two groups. Drowsiness was reported by about twice as many women in the meclizine pretreatment group (31%) than in the other two groups (13% in the placebo group, 16% in the no-pretreatment group; P < .01 for both comparisons). Conclusion: Meclizine is effective for preventing nausea and vomiting associated with the Yuzpe Regimen of emergency contraceptive pills. Women using this drug should be cautioned to anticipate drowsiness.
Charlotte Ellertson - One of the best experts on this subject based on the ideXlab platform.
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Extending the time limit for starting the Yuzpe Regimen of emergency contraception to 120 hours.
Obstetrics and gynecology, 2003Co-Authors: Charlotte Ellertson, Margaret Evans, Sue Ferden, Clare Leadbetter, Aileen Spears, Karen Johnstone, J TrussellAbstract:Abstract Objective Current protocols state that the Yuzpe Regimen of emergency contraception can be initiated up to 72 hours after unprotected intercourse. The purpose of this study was to determine whether the window for emergency hormonal contraception can be extended to 120 hours. Methods In an observational study, we tracked 111 women who requested emergency contraception between 72 and 120 hours after unprotected sex but refused postcoital copper intrauterine devices (IUDs), preferring instead the Yuzpe Regimen. We compared failure rates for this group with rates among 675 otherwise similar women who started the same therapy within 72 hours. Results Both perfect use (1.9%) and typical use (3.6%) failure rates were low among women presenting between 72 and 120 hours after unprotected intercourse. These rates did not statistically differ from failure rates for the standard Yuzpe Regimen (2.0% during perfect use and 2.5% during typical use). Our small sample size of 111, however, gave us just 25% power to detect a doubling in the failure rates (2% to 4%) and 59% power to detect a tripling in the failure rates (2% to 6%). Conclusion The 72-hour cutoff for the Yuzpe Regimen of emergency contraception appears needlessly restrictive. Women who request this therapy more than 72 hours after unprotected sex should be allowed to receive it, particularly if they decline postcoital insertion of a copper IUD and would otherwise have no options for reducing pregnancy risk.
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Extending the time limit for starting the Yuzpe Regimen of emergency contraception to 120 hours
Obstetrical & Gynecological Survey, 2003Co-Authors: Charlotte Ellertson, Margaret Evans, Sue Ferden, Aileen Spears, Karen Johnstone, Clare Ledbetter, J TrussellAbstract:In conjunction with a study of modifications to the Yuzpe Regimen of emergency contraception delivered with 72 hours of unprotected intercourse, the authors conducted a second prospective trial that investigated the efficacy of the Regimen beyond 72 hours. Both trials accepted women aged 16-45 years (in the United States, 18-45 years) with regular menstrual cycles who had unprotected intercourse between 10 days before and 6 days after expected ovulation and who refused a copper intrauterine device. Participants had to be willing to abstain from unprotected intercourse during the study cycle and willing to return for a follow-up visit. The Yuzpe Regimen used consisted of 100 μg of ethanol estradiol plus 1.0 mg of norgestrel repeated after 12 hours. Study patients were women who presented 4-5 days after unprotected intercourse (n = 111); women enrolled in the first trial served as control subjects (n = 675). Overall, 3.7% (4 of 111) of women treated in the extended time period became pregnant compared with 2.5% of control subjects (17 of 675), but the difference was not significant. It was determined that 2 (1.9%) study patients and 12 (2.5%) patients in the control group had followed the Regimen perfectly. Women who strayed from the prescribed standard 2-dose Regimen were considered typical users. Perfect use of the Regimen within 1-3 days prevented 77% expected pregnancies in women who received no intervening therapy after unprotected intercourse, and perfect use within 3-4 days prevented 73% of expected pregnancies.
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Effectiveness of the Yuzpe Regimen of emergency contraception by cycle day of intercourse: implications for mechanism of action.
Contraception, 2003Co-Authors: J Trussell, Charlotte Ellertson, Laneta DorflingerAbstract:Abstract Objective The purpose of this study was to provide evidence about the mechanism of action of the Yuzpe method of emergency contraception by examining effectiveness by cycle day of intercourse relative to ovulation. Methods Through a literature search, we identified eight studies that present the number of women treated and outcome of treatment by cycle day of unprotected intercourse relative to expected day of ovulation. Using five sets of external estimates of conception probabilities by cycle day of intercourse among women not using contraception, we assessed and compared the effectiveness of the Yuzpe Regimen by whether intercourse occurred on or before the second day before ovulation or afterward, and whether intercourse occurred on or before the first day before ovulation or afterward. Results In 36 of the 45 pairs of estimates of effectiveness, based on eight separate studies and the eight studies combined and five different sets of conception probabilities by cycle day, effectiveness was higher—and in most cases substantially higher—when intercourse occurred on or before the second day before ovulation (day −2) than when it occurred later. When data were stratified by whether intercourse occurred on or before the day before ovulation (day −1), effectiveness was greater when intercourse occurred early in 43 of 45 pairs. Conclusions These results suggest that one hypothesized mechanism of action of the Yuzpe method, inhibiting implantation of a fertilized egg, is unlikely to be the primary mechanism of action.
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Modifying the Yuzpe Regimen of emergency contraception: a multicenter randomized controlled trial.
Obstetrics and gynecology, 2003Co-Authors: Charlotte Ellertson, Tara Shochet, Kelly Blanchard, Anne Webb, Alison Bigrigg, Sue Haskell, J TrussellAbstract:Abstract Objective Emergency contraceptives can prevent unintended pregnancy after unprotected intercourse. The best-studied Regimen (“Yuzpe”) consists of ordinary combined oral contraceptives containing levonorgestrel and ethinyl estradiol. Women traditionally take one dose within 72 hours after unprotected intercourse, and a second dose 12 hours later. Historically, half experience nausea and a fifth vomit. The purpose of this study was to determine whether 1) women could use combined oral contraceptives other than those containing levonorgestrel and 2) eliminating the second dose improves comfort and convenience. Methods Women presenting within 72 hours after unprotected intercourse were randomized to receive 1) standard two-dose Yuzpe, 2) a variant of Yuzpe substituting norethindrone for levonorgestrel, or 3) only the first dose of Yuzpe, followed 12 hours later by a placebo. Results Perfect-use failure rates were low in all groups and did not differ in a statistically significant way (standard Yuzpe 2.0% [n = 589], norethindrone–ethinyl estradiol 2.7% [n = 547], single dose of Yuzpe 2.9% [n = 546]). Typical-use failure rates were slightly higher but similarly did not differ significantly. Side effects were similar across groups, except that women taking the single dose reported half the vomiting. Taking the pills with food did not seem to reduce nausea or vomiting, and the pills were not more effective when started sooner after unprotected intercourse. Conclusion Oral contraceptives containing norethindrone–ethinyl estradiol work approximately as well for emergency contraception as levonorgestrel–ethinyl estradiol formulations and should be offered when first-line therapies are not available.
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Estimating the effectiveness of emergency contraceptive pills.
Contraception, 2003Co-Authors: J Trussell, Helena Von Hertzen, Charlotte Ellertson, Margaret Evans, Sue Ferden, Anne Webb, Allison Bigrigg, Clare LeadbetterAbstract:Abstract Objective We use new estimates of conception probabilities by cycle day of intercourse, where cycle day is measured with day 1 being the first day of bleeding in a cycle, to propose a new approach for estimating the effectiveness of emergency contraceptive pills (ECPs). We use this new approach to examine the absolute effectiveness and the cost-effectiveness of ECPs and whether ECPs are more effective the sooner after unprotected intercourse they are initiated. Methods Using the new set of conception probabilities, we employ data from two recent clinical trials of ECPs, one from the Population Council and the other from the World Health Organization (WHO), to examine the effectiveness of the combined ECP Regimen. Results The expected pregnancy rate among typical users was 6.2% in the Population Council trial and 7.4% in the WHO trial based on conception probabilities by cycle day relative to the day of ovulation. Based on conception probabilities by cycle day relative to the first day of bleeding, the expected pregnancy rates dropped to 5.4% and 5.2%, respectively. The two trials yield conflicting evidence regarding whether effectiveness declines with treatment delay. Conclusions Our results suggest that the absolute levels of effectiveness for the Yuzpe Regimen of emergency contraception and the cost-effectiveness of this Regimen have probably been overstated when based on conception probabilities by cycle day relative to day of ovulation.
Frank Z. Stanczyk - One of the best experts on this subject based on the ideXlab platform.
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Comparison of vaginal and oral administration of emergency contraception.
Fertility and sterility, 2005Co-Authors: Eliran Mor, Peyman Saadat, Richard J. Paulson, Robert L. Reid, Sari Kives, Emily White, Frank Z. StanczykAbstract:Objective To compare the physiologic effects of vaginally and orally administered emergency contraception. Design Prospective, open-label, crossover study. Setting University research center. Patient(s) Nine regularly menstruating volunteers. Intervention(s) Five subjects received 1,000 μg of levonorgestrel with 200 μg of ethinyl E 2 (twice the standard Yuzpe Regimen dose) vaginally, and the standard Yuzpe Regimen dose orally 1 week later. Four subjects received 1,500 μg of levonorgestrel (twice the standard Plan B Regimen dose) vaginally and received the standard Plan B dose orally 1 week later. Serum samples were obtained at baseline and at frequent intervals after each dose. Main Outcome Measure(s) Serum gonadotropin, hepatic globulin, and androgen levels measured at baseline, at the time of peak levonorgestrel, and 24 hours later. Result(s) Gonadotropin, hepatic globulin, and androgen levels were suppressed to a similar degree among the four Regimens, with a return to baseline levels after 24 hours. Conclusion(s) We conclude that high doses of levonorgestrel found in emergency contraception Regimens lead to a transient direct suppression of gonadotropin, hepatic globulin, and androgen levels. This effect is similar after vaginal and oral administration of emergency contraception. Therefore, the vaginal route of administration of emergency contraception Regimens may be as efficacious as the oral route.
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Bioavailability of the Yuzpe and levonorgestrel Regimens of emergency contraception: vaginal vs. oral administration.
Contraception, 2005Co-Authors: Sari Kives, Frank Z. Stanczyk, Philip M. Hahn, Emily White, Robert L. ReidAbstract:Abstract Separate crossover studies compared the bioavailability of oral vs. vaginal routes of administration for the Yuzpe ( n =5) and levonorgestrel Regimens ( n =4) of emergency contraception. Twice the standard dose of the Yuzpe Regimen (200 ��g of ethinyl estradiol, 1000 ��g of levonorgestrel) or the levonorgestrel Regimen (1500 ��g of levonorgestrel) was self-administered vaginally. One week later, each subject received orally the standard dose of the assigned medication. Serial blood samples were collected over 24 h and assayed for levonorgestrel and ethinyl estradiol (for the Yuzpe Regimen only). Paired t tests were used to compare oral vs. vaginal administration for maximum concentration ( C max ), time to maximum concentration ( T max ) and area under the curve over 24 h (AUC 0���24 ). Relative bioavailability (vaginal/oral) was derived from AUC 0���24 . Vaginal administration of double the standard dose of the Yuzpe Regimen resulted in a lower C max (vaginal=5.4 vs. oral=14.6 ng/mL, p=.038) and a later T max (5.9 vs. 2.0 h, p=.066) for levonorgestrel, compared to oral administration. Corresponding ethinyl estradiol concentrations were higher (786 vs. 391 pg/mL, p=.039) and peaked later (4.0 vs. 1.9 hr, p=.154) with vaginal administration. Relative bioavailabilities for levonorgestrel and ethinyl estradiol were 58% and 175%, respectively. Similarly, vaginal administration of the levonorgestrel Regimen resulted in a lower C max (vaginal=5.4 vs. oral=15.2 ng/mL, p=.006) and a later T max (7.4 vs. 1.3 h, p=.037) for levonorgestel, compared to oral administration. The relative bioavailability was 62%. Our preliminary data suggest that vaginal administration of these emergency contraception Regimens appears to require at least three times the standard oral dose to achieve equivalent systemic levonorgestrel concentrations.
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Alterations in gonadotropin levels following oral and vaginal administration of the Yuzpe Regimen and Plan B for emergency contraception.
Fertility and Sterility, 2002Co-Authors: Eliran Mor, Peyman Saadat, S. Kives, Chunying Zhang, Richard J. Paulson, Robert L. Reid, Frank Z. StanczykAbstract:There is increasing use of the Yuzpe Regimen [500g levonorgestrel (LNG)/100g ethinyl estradiol] and Plan B (750g LNG) for emergency contraception. These Regimens are believed to act by delay of ovulation in conjunction with a local effect on the endometrium; however the exact mechanism of action is unknown. Furthermore data regarding vaginal administration of both Regimens are lacking. The objective of this study was to determine the effects of Plan B and Yuzpe Regimens administered orally or vaginally on serum gonadotropin levels at peak and nadir LNG levels. There was no significant difference in LH and FSH suppression between Plan B and the Yuzpe Regimens suggesting that when high doses of LNG are used (Plan B) the addition of EE as in the Yuzpe Regimen contributes little to further gonadotropin suppression. Vaginally administered Plan B and Yuzpe Regimens did not differ significantly from the same Regimens administered orally in suppression of LH and FSH suggesting that vaginal administration of such Regimens may be as efficacious as oral ones in delaying ovulation. (excerpt)
Joseph B. Stanford - One of the best experts on this subject based on the ideXlab platform.
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Postfertilization effect of hormonal emergency contraception. Ann Pharmacother 2002;36:465-70
2016Co-Authors: Chris Kahlenborn, Joseph B. Stanford, Walter L LarimoreAbstract:Emergency contraception (EC) consists of hormones ormechanical devices used within 72 hours of sexual in-tercourse with the intent of preventing pregnancy. In the late 1960s and early 1970s, women used high-dose estro-gens such as diethylstilbestrol as EC.1 This treatment was replaced in 1974 by combination high-dose oral contra-ceptives (OCs) (e.g., ethinyl estradiol/levonorgestrel) used within a 12-hour interval (i.e., the Yuzpe Regimen) and, in later years, by Plan B, which consists of 2 levonorgestrel tablets.2 The intrauterine device, danazol (danocrine), and mifepristone have also been studied and promoted as EC, but the Yuzpe Regimen remains the most prevalent form of EC in the US and Europe.3 The question as to whether hormonal EC sometimes acts after fertilization to prevent implantation, called a postfertilization effect (i.e., early abortion), is important and could have far-reaching implications given the differ-ing attitudes in regard to its use and related issues such as informed consent, emergency department rape protocols, and conscience clauses. Postfertilization effect refers to any effect that reduces the survival rate of the zygote/em-bryo after fertilization, usually prior to clinical recognition of pregnancy. We use the term early abortion synonymous-ly with postfertilization effect. We recognize that some physicians,4 geneticists, and ethicists have arbitrarily de-fined human life as beginning after implantation, thereby eschewing the possibility of an early abortion prior to im-plantation. However, we recognize the traditional defini-tion of pregnancy: “the gestational process, comprising th
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False risk attribution results in misleading assessment of the relationship between suppression of ovulation and the effectiveness of the Yuzpe Regimen for emergency contraception.
Contraception, 2003Co-Authors: Rafael T. Mikolajczyk, Joseph B. StanfordAbstract:These estimated effectiveness rates are based on the study of Croxatto et al.and accepted parameters for the probability of pregnancy during the fertile window. The weighted scenarios are the most realistic in terms of likely coital patterns for most users of emergency contraception. All scenarios yield effectiveness estimates that are considerably lower than estimated effectiveness for clinical performance of the Yuzpe Regimen of 74% (95% confidence interval 63% to 79%) [15]. As illustrated in Table 2 these results are robust across a variety of underlying presumptions about the fertilizability of ova released with abnormal or unknown LH patterns. Therefore mechanisms other than disturbance of ovulation must be active to account for the clinical effectiveness of the Yuzpe Regimen of emergency contraception. (excerpt)
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postfertilization effect of hormonal emergency contraception
Annals of Pharmacotherapy, 2002Co-Authors: Chris Kahlenborn, Joseph B. Stanford, Walter L LarimoreAbstract:OBJECTIVE:To assess the possibility of a postfertilization effect in regard to the most common types of hormonal emergency contraception (EC) used in the US and to explore the ethical impact of this possibility.DATA SOURCES AND STUDY SELECTION:A MEDLINE search (1966–November 2001) was done to identify all pertinent English-language journal articles. A review of reference sections of the major review articles was performed to identify additional articles. Search terms included emergency contraception, postcoital contraception, postfertilization effect, Yuzpe Regimen, levonorgestrel, mechanism of action, Plan B.DATA SYNTHESIS:The 2 most common types of hormonal EC used in the US are the Yuzpe Regimen (high-dose ethinyl estradiol with high-dose levonorgestrel) and Plan B (high-dose levonorgestrel alone). Although both methods sometimes stop ovulation, they may also act by reducing the probability of implantation, due to their adverse effect on the endometrium (a postfertilization effect). The available evide...
