Electrocatalytic detection of estradiol at a carbon nanotube|Ni(Cyclam) composite electrode fabricated based on a two-factorial design

In this work, we have developed a carbon nanotube|Ni(cyclam)-coated glassy carbon electrode to achieve minimal fouling effects and to catalyse the oxidation of the oestrogen, estradiol, during voltammetric detection. This electrode was fabricated by initially applying a Nafion-carbon nanotube mixture, and then electropolymerising Ni(cyclam) complexes on the electrode. During this process, a two-level factorial design was used to optimise experimental parameters including the amount of carbon nanotubes, the concentration of Nafion and the surface coverage of Ni(cyclam). A linear calibration plot between 0.5 and 40 microM estradiol was then obtained in synthetic laboratory standard solutions. Based on a signal-to-noise ratio of 3, a detection limit of 60 nM was estimated, which is below the typical estradiol level measured in a normal menstrual cycle. The electrodes were subsequently applied to the detection of estradiol in protein-free human serum samples. Comparable sensitivity between synthetic laboratory standard solutions and serum samples was obtained, indicating minimal interference effects from the serum matrix.

Indinavir Pharmacokinetics during Different Phases of the Menstrual Cycle in HIV-Infected Women

OBJECTIVE

To characterise the pharmacokinetics of indinavir during different phases of the menstrual cycle in HIV-infected women.

DESIGN

Open-label study.

SETTING

The immunodeficiency clinic at Erie County Medical Center, Buffalo, New York.

PATIENTS

Ten HIV-infected women were enrolled in the study. Eligibility criteria included an acceptable medical history, chemistry profile, complete blood count with differential, lymphocyte profile, urinalysis and history of a regular menstrual cycle. PATIENTS had to be on a stable antiretroviral regimen that included indinavir 800mg taken every 8 hours.

INTERVENTIONS

Blood sampling over an 8-hour period following an 800mg dose of indinavir during the menstrual, follicular and luteal phases of the menstrual cycle.

MAIN OUTCOME MEASURES

Pharmacokinetic parameters in ten HIV-infected women adherent with indinavir 800mg every 8 hours during the menstrual, follicular and luteal phases of the menstrual cycle. Serum estradiol and progesterone levels were also obtained during each menstrual cycle phase.

RESULTS

The peak plasma concentration, plasma concentration 8 hours after administration of a given dose of indinavir, elimination half-life and oral clearance of indinavir were not significantly different across the menstrual cycle phases. Indinavir exposure varied among the female patients with some individuals having similar areas under the concentration-time curve (AUCs) during the three phases while others had notable differences in AUC. Maximum plasma indinavir concentrations were highest during the follicular phase in four subjects, highest during the luteal phase in two individuals, and highest during the menstrual phase in three patients.

CONCLUSIONS

No differences were found in indinavir pharmacokinetics during the menstrual cycle phases. Significant intra- and interpatient variability in indinavir pharmacokinetics were observed; however, indinavir exposure in women did not appear to be excessive compared with pharmacokinetic data obtained from prior studies conducted in men.