A novel breath test to directly measure use of vaginal gel and condoms.

We assessed the feasibility of a breath test to detect women's single or concurrent use of vaginal products by adding ester taggants to vaginal gel and condom lubricant. Healthy non-pregnant women were enrolled into a two-day cohort (N = 13) and a single-day cohort (N = 12) in San Francisco. Within each cohort, women were randomized (5:1) to tagged or untagged products, and inserted in a clinical setting: 4 mL of tenofovir placebo gel (ten tagged with 15 mg 2-pentyl acetate; three untagged), and an artificial phallus with a lubricated condom (11 tagged with 15 mg 2-butyl acetate; two untagged), on two separate days (two-day cohort) or concurrently (single-day cohort). Using a portable mini-gas chromatograph, the presence/absence of taggants was determined in breath specimens collected prior to, and at timed intervals following product exposure. Demographic, clinical and product use experience data were collected by structured interview. All participants completed all visits and inserted their assigned products. At 5 min post-insertion, the breath test was 100% accurate in identifying insertion of the tagged (or untagged) gel and/or condom. The half-life in breath of the two esters tested was <1 h with large variability between individuals, taggants and cohorts. Overall, among those receiving tagged product, six mild and two moderate product-related AEs were reported. All were transient and resolved spontaneously. Additional sensations included taste in mouth (N = 4) and scent (N = 5). The tagged products were well tolerated. This breath test has the potential to accurately and objectively monitor adherence to vaginal gel and condom used separately or concurrently.

HPLC method validation for the quantification of lomustine to study pharmacokinetics of thermosensitive liposome-encapsulated lomustine containing iohexol for CT imaging in C6 glioma rats.

To study the pharmacokinetics of the novel lomustine liposome, a specific, simple, and reliable high-performance liquid chromatography with ultraviolet detection (HPLC/UV) method for quantification of lomustine in rat plasma was established and validated. The calibration curve was linear over the concentration range of 0.05-5 µg/mL with the linearity (r (2)) being ≥0.9994. The intra- and inter-day precision was less than 5.87 and 10.47%, respectively, and the accuracy was within ±7.95%. The validated method has been successfully applied to a pharmacokinetic study of thermosensitive liposome-encapsulated lomustine containing iohexol and lomustine solution after intravenous administration to C6 glioma rats. Population pharmacokinetic (PPK) analysis was performed using NONMEM program for the plasma concentration versus time data. A one-compartment model with first-order elimination was established and proved to be the best description of the lomustine profile. Bootstrap analysis (n = 1,000) was executed to evaluate the stability and robustness of the model. The pharmacokinetic parameters of lomustine liposome containing iohexol and lomustine solution in rats were simulated using the final PPK model: t (1/2), AUC(0-∞), C (max) were 0.28 ± 0.12, 0.19 ± 0.08, and 0.30 ± 0.13 h; 2.37 ± 0.76, 1.32 ± 0.42, and 0.90 ± 0.29 mg h/L; 5.15 ± 2.22, 3.91 ± 1.90, and 1.87 ± 0.35 µg/mL for heated, non-heated, and control group, respectively. The result indicated that thermosensitive liposome-encapsulated lomustine containing iohexol for CT imaging had different pharmacokinetic characteristics than lomustine solution. Compared with non-heated group, the bioavailability of lomustine was obviously increased in C6 glioma rat plasma.