Estimating systemic exposure to ethinyl estradiol from an oral contraceptive.

OBJECTIVE: This study was conducted to compare single-dose pharmacokinetics of ethinyl estradiol in an oral contraceptive with steady-state values and to assess whether any simpler measures could provide an adequate proxy of the "gold standard" 24-hour steady-state area under the curve (AUC) value. Identification of a simple, less expensive measure of systemic ethinyl estradiol exposure would be useful for larger studies that are designed to assess the relationship between an individual's ethinyl estradiol exposure and side-effects. STUDY DESIGN: We collected 13 samples over 24 hours for pharmacokinetic analysis on days 1 and 21 of the first cycle of a monophasic oral contraceptive that contained 30 µg ethinyl estradiol and 150 µg levonorgestrel in 17 nonobese healthy white women. We also conducted an abbreviated single-dose 9-sample pharmacokinetic analysis after a month washout. Ethinyl estradiol was measured by liquid chromatography-tandem mass spectrometry. We compared results of a full 13-sample steady-state pharmacokinetic analysis with results that had been calculated with the use of fewer samples (9 or 5) and after the single doses. We calculated Pearson correlation coefficients to evaluate the relationships between these estimates of systemic ethinyl estradiol exposure. RESULTS: The AUC, maximum, and 24-hour values were similar after the 2 single oral contraceptive doses (AUC; r=0.92). The steady-state 13-sample 24-hour AUC value was correlated highly with the average 9-sample AUC value after the 2 single doses (r=0.81; P=.0002). This correlation remained the same if the number of single-dose samples was reduced to 4, taken at time 1, 2.5, 4, and 24 hours. The 24-hour value at steady-state was correlated highly with the 24-hour steady-state AUC value (r=0.92; P<.0001). The average of the 24-hour values after the 2 single doses was also correlated quite highly with the steady-state AUC value (r=0.72; P=.0026). CONCLUSION: Limited blood sampling, including results from 2 single doses, gave highly correlated estimates of an oral contraceptive user's steady-state ethinyl estradiol exposure.

Adolescent vaccine co-administration and coverage in New York City: 2007-2013.

OBJECTIVES: To investigate adolescent vaccination in New York City, we assessed tetanus, diphtheria, and acellular pertussis (Tdap), meningococcal conjugate (MCV4), and human papillomavirus (HPV) vaccine uptake, vaccine co-administration, and catch-up coverage over time. METHODS: We analyzed data from the Citywide Immunization Registry, a population-based immunization information system, to measure vaccine uptake and co-administration, defined as a Tdap vaccination visit where MCV4 or HPV vaccine was co-administered, among 11-year-olds. Catch-up vaccinations were evaluated through 2013 for adolescents born 1996 to 2000, by birth cohort. HPV vaccination among boys included data from 2010 to 2013. RESULTS: Adolescent vaccine administration was greatest during the back-to-school months of August to October and was highest for Tdap. Although MCV4 uptake improved over the study years, HPV vaccine uptake among girls stagnated; boys achieved similar uptake of HPV vaccine by 2012. By 2013, 65.4% had MCV4 co-administered with Tdap vaccine, whereas 28.4% of girls and 25.9% of boys had their first dose of HPV vaccine co-administered. By age 17, Tdap and MCV4 vaccination coverage increased to 97.5% and 92.8%, respectively, whereas ≥1-dose and 3-dose HPV vaccination coverage were, respectively, 77.5% and 53.1% for girls and 49.3% and 21.6% for boys. Age-specific vaccination coverage increased with each successive birth cohort (P < .001). CONCLUSIONS: From 2007 to 2013, there were greater improvements in Tdap and MCV4 vaccination than HPV vaccination, for which co-administration with Tdap vaccine and coverage through adolescence remained lower. Parent and provider outreach efforts should promote timely HPV vaccination for all adolescents and vaccine co-administration.