***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND This study was conducted to compare ovarian activity of an oral contraceptive containing drospirenone ( drsp ) 3 mg plus ethinylestradiol ( EE ) 20 mcg administered in 24/4 regimen compared with the conventional 21/7 regimen , during intended use and following predefined dosing errors . STUDY DESIGN Women aged 18 - 35 years who ovulated or had a follicular diameter of > or=15 mm on or before Day 23 during a pretreatment cycle were admitted into this double-blind , r and omized study . Participants underwent 3 treatment cycles with drsp 3 mg/EE 20 mcg in a 24/4 ( n=52 ) or a 21/7 ( n=52 ) regimen . In the third treatment cycle , the initial three pills in both groups were replaced with placebos .  Ovarian activity was classified using the Hoogl and scale during pretreatment and during Cycles 2 and 3 . RESULTS Suppression of ovarian activity was more pronounced with the 24/4 regimen -- the odds ratio for a lower Hoogl and score ( i.e. , greater ovarian suppression ) with the 24/4 regimen compared with the conventional 21/7 regimen were 6.01 ( 95 % CI : 2.29 - 17.94 ) and 3.06 ( 95 % CI : 1.44 - 6.65 ) for Cycles 2 and 3 , respectively . More women in the 24/4 regimen group had no ovarian activity 87.8 % vs. 56.0 % during Cycle 2 and 55.1 % vs. 30.0 % during Cycle 3 . The 24/4 regimen was associated with a more consistent suppression ( less fluctuation ) of endogenous estradiol . CONCLUSION The drsp 3 mg/EE 20 mcg oral contraceptive in a 24/4 regimen was associated with greater ovarian suppression ( despite intentional dosing error ) , which results in decreased hormonal fluctuations , and may increase contraceptive efficacy with the low-dose formulation OBJECTIVE : To estimate whether women receiving daily text-message reminders have increased oral contraceptive pill adherence compared with women not receiving reminders . METHODS : This r and omized controlled trial estimated whether there was an effect of daily text-message reminders on oral contraceptive pill adherence of new oral contraceptive pill users . Pill-taking was tracked for 3 months by an electronic monitoring device with wireless data collection . During the study period , participants assigned the intervention received a daily reminder text message .  Eighty-two women were assigned r and omly to detect a 1.6±2.0 pill difference ( 90 % power , 5 % & agr ; , 15 % dropout ) . RESULTS : Participants were 79 % white , non-Hispanic , 99 % high school graduates , and 99 % nulliparous with a mean age of 22 years . Most reported condom use  with past coital activity , and more than half reported prior emergency contraception use . The mean number of missed pills per cycle did not differ significantly between the groups : 4.9±3.0 for the text-message group and 4.6±3.5 for the control group ( P=.60 ) . The number of missed pills per cycle increased over the course of the study , but this pattern did not increase differentially between the groups . Adherence recorded by the electronic monitoring device indicated much poorer adherence than that recorded by patient diaries . Despite poor pill-taking , there were no pregnancies . CONCLUSION : Daily text-message reminders did not improve oral contraceptive pill adherence . Although the lack of benefit may be attributed to the frequent use of alternative reminder systems in the control group , the rate of missed pills when measured objective ly was still very high in both groups . CLINICAL TRIAL REGISTRATION : Clinical trials.gov , www . clinical trials.gov , NCT00733707 . LEVEL OF EVIDENCE : OBJECTIVE To compare ovulation inhibition and ovarian activity with 21-day and 24-day regimens of a low-dose combined oral contraceptive ( COC ) containing 60 microg of gestodene and 15 microg of ethinyl estradiol . DESIGN Interventional observational study . SETTING Reproductive medicine unit . PATIENT(S ) Fifty-eight healthy volunteers aged 18 - 35 years . INTERVENTION(S ) Ovarian activity was monitored every other day with the use of ultrasound to measure the diameters of follicle-like structures and blood sample s to measure serum concentrations of 17beta-E2 and progesterone . Subjects were observed for five cycles : pretreatment and posttreatment control cycles and three cycles in which the COC was administered for either 21 or 24 days of each cycle . MAIN OUTCOME MEASURE(S ) Occurrence of ovulation and evidence of ovarian activity . RESULT ( S ) The study was completed by 27 ( 90 % ) of the 30 subjects who received the 24-day regimen and by 24 ( 79 % ) of the 28 subjects who received the 21-day regimen . Ovulation was inhibited in all cycles in the 24-day group and in 74 of 75 cycles in the 21-day group . Luteinized unruptured follicles were seen in no cycles with the 24-day regimen and in 6 ( 8 % ) of 75 cycles with the 21-day regimen . Mean ovarian follicular development and serum 17beta-E2 and progesterone levels were lower in the 24-day group . CONCLUSION ( S ) The 24-day regimen is an innovative strategy for maintaining effective ovulation inhibition at ultra-low doses of contraceptive steroids Objectives The primary objective of this analysis was to characterise the steady-state pharmacokinetics ( PK ) of ethinylestradiol ( EE ) and drospirenone ( DRSP )  in a r and omised Phase III study that investigated the contraceptive efficacy and safety of three different regimens of EE 20 µg/DRSP 3 mg . Methods Non-linear mixed-effects modelling was used to develop population PK models for EE and  DRSP . EE and DRSP serum concentrations were determined in blood sample s obtained from approximately 1100 healthy young women on two occasions during the first cycle ( Week 3 ) and after 6 months ( Week 27 ) of EE 20 µg/DRSP 3 mg use . EE 20 µg/DRSP 3 mg was administered as a flexible extended regimen [ 24–120 days ’ active hormonal intake followed by 4 days with no tablet intake ( tablet-free interval ) ] , a conventional 28-day cyclic regimen ( 24 days ’ active hormonal intake followed by 4 days of placebo tablets ) or a fixed extended regimen ( 120 days ’ uninterrupted active hormonal intake followed by a 4-day tablet-free interval ) over 1 year . Results The population PK of EE and DRSP in this population were successfully described using the developed population models . All three regimens led to similar steady-state drug exposure during long-term treatment . Only minor changes ( ≤8 % ) in the steady-state PK of EE and DRSP were observed between Week 3 and Week 27 of an extended regimen . Body weight ( BW ) and age had a small , statistically significant impact on the PK of EE and DRSP ( BW only ) in a covariate analysis , however , these changes were not considered to be clinical ly relevant . Conclusions Extending the established 24/4-day regimen of EE 20 µg/DRSP 3 mg does not change the known steady-state PK of EE and DRSP , suggesting that the clinical efficacy is also similar . This is in line with the published clinical results from this study 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 r and omized 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 BACKGROUND Unscheduled bleeding may affect satisfaction and compliance with extended oral contraceptive ( OC ) regimens . The bleeding patterns of two variants of a flexible dosing regimen design ed to manage intracyclic bleeding problems during extended cycles were compared with that of a conventional OC regimen . STUDY DESIGN This was a 1-year , open-label , active-controlled , Phase 3 study conducted in the USA . Healthy women ( 18 - 45 years ) received an ethinylestradiol ( EE ) 20 mcg/drospirenone 3 mg OC in two flexible extended regimens or in a conventional 24/4 ( i.e. , 28-day ) regimen . The primary regimen [ management of intracyclic bleeding ( flexible(MIB ) ) regimen ] was an extended dosing regimen that required subjects to initiate 4-day tablet-free intervals after 3 days of breakthrough bleeding/spotting . An alternative extended regimen [ active period control ( flexible(APC ) ) regimen ] allowed subjects to initiate a 4-day tablet-free interval irrespective of the occurrence of bleeding . Bleeding profiles were compared between treatments . Efficacy and safety outcomes were also assessed . RESULTS The full analysis set comprised 1864 women ( flexible(MIB ) , N=1406 ; flexible(APC ) , N=232 ; conventional 24/4 , N=226 ) . Over 1 year , subjects in the flexible(MIB ) group experienced significantly fewer ( mean±SD , 40±30 ) bleeding/spotting days than those in the conventional 24/4 group ( 52±35 ) . The corresponding value in the flexible(APC ) group was 47±33 days . The pregnancy rate in the flexible(MIB ) group was 1.65 per 100 woman-years ( 95 % confidence interval , 0.96 - 2.65 ) . All three regimens were well tolerated . CONCLUSION A flexible(MIB ) dosing regimen of EE 20 mcg/drospirenone 3 mg is associated with good contraceptive efficacy and fewer bleeding/spotting days than the conventional 24/4 regimen BACKGROUND The study was conducted to evaluate follicular development and hormone patterns with three oral contraceptive ( OC ) regimens before , during and after the 7-day hormone-free interval ( HFI ) or 7-day ethinyl estradiol (EE)-supplemented interval . STUDY DESIGN The study is a single-center , open-label , prospect i ve , r and omized trial to evaluate pituitary-ovarian suppression with three OC regimens containing identical hormones : 30 mcg of EE and 150 mcg of levonorgestrel ( LNG ) . METHODS After a st and ard 21/7 OC baseline cycle , subjects were r and omized to one of three treatment groups : ( 1 ) three 21/7-day cycles of 150 mcg LNG/30 mcg EE for 21 days followed by 7 days of placebo ( n=10 ) ; ( 2 ) one 84/7-day cycle of 150 mcg LNG/30 mcg EE for 84 days followed by 7 days of placebo ( n=12 ) and ( 3 ) one 84/7EE-day cycle of 150 mcg LNG/30 mcg E 
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Results There is considerable inter- and intra-individual variation in the absorption and metabolism of COCs .
This risk increases in typical users whenever the CFI is prolonged : late restarts are a common reason for pill omissions .
Shortening or eliminating the CFI improves contraceptive efficacy using the lowest doses available , without evidence to date of compromised safety .
Conclusions There is no scientific evidence to support a 7-day CFI and it should be replaced either by a continuous flexible regimen , or extended regimens with a shortened CFI , prescribed first-line .
In women preferring a monthly ‘ bleed ’ , a 4-day CFI similarly provides a greater safety margin when pills are omitted