The aims of this study were to evaluate free levels of fluconazole (FCZ) in the kidneys of healthy and Candida albicansinfected Wistar rats using microdialysis and to establish the relationship between free renal and total plasma levels under both conditions. Microdialysis recovery rates were determined in vitro by dialysis, and retrodialysis recovery rates were determined in vivo by retrodialysis. The recovery rate was around 50%, independent of the method, drug concentration, or condition (in vitro or in vivo) used. FCZ kidney penetration in healthy and infected rats was investigated after the administration of 10 mg/kg of body weight intravenously (i.v.) or 50 mg/kg orally (n ‫؍‬ 6/group) and blood and microdialysate sample harvesting at predetermined time points up to 24 and 18 h, respectively. There were no statistical differences between the area under the free concentration-time curve (AUC 0 -ؕ ) values in plasma and in tissue for either healthy or infected groups for the same dose regimen investigated. The antifungal tissue penetrations were similar for both doses and under all conditions investigated (ranging from 0.77 to 0.84). The unbound fraction of FCZ was concentration independent (86.0% ؎ 2.0%), allowing the prediction of free renal levels using pharmacokinetic parameters obtained from total plasma fitting. The results showed that free renal and free plasma levels are similar in healthy and systemically C. albicansinfected rats. Therefore, free plasma levels are a good surrogate to estimate free FCZ renal concentrations in systemic candidiasis and can be used to optimize dosing regimens for this drug.

Objective:To evaluate the complete pathologic response attained by patients diagnosed with locally advanced breast cancer submitted to neoadjuvant chemotherapy based on the doxorubicin/ cyclophosphamide regimen followed by paclitaxel.Methods:A retrospective cohort of patients with locally advanced breast cancer, admitted to the Hospital de Câncer de Barretos between 2006 and 2008 submitted to the doxorubicin/cyclophosphamide protocol followed by paclitaxel (4 cycles of doxorubicin 60mg/m2 and cyclophosphamide 600mg/m2 every 21 days; 4 cycles of paclitaxel 175mg/m2 every 21 days). The following variables were assessed: age, menopause, performance status, initial clinical staging, anthropometric data, chemotherapy (dose – duration), toxicity profile, post-treatment staging, surgery, pathologic complete response rate, disease-free survival, and pathological characteristics (type and histological degree, hormonal profile and lymph node involvement). Statistical analysis was performed using a 5% level of significance.Results:Of the 434 patients evaluated, 136 were excluded due to error in staging or because they had received another type of chemotherapy. Median age was 50 years, all with performance status 0-1. Median initial clinical size of tumor was 65mm and the median final clinical size of the tumor was 22mm. Fifty-one (17.1%) patients experienced a pathologic complete response. Those with a negative hormonal profile or who were triple-negative (negative Her-2 and hormonal profile) experienced a favorable impact on the pathologic complete response.Conclusion:Neoadjuvant chemotherapy with doxorubicin/ cyclophosphamide followed by paclitaxel provided a pathologic complete response in the population studied in accordance with that observed in the literature. Triple-negative patients had a greater chance of attaining this response.

The aim of this work was to compare the pharmacological properties of levofloxacin and gatifloxacin against Streptococcus pneumoniae by pharmacokinetic/pharmacodynamic (PK/PD) modelling of the time-kill curves employing an E(max) model. An in vitro infection model was used to simulate free pulmonary fluctuating concentrations expected after multiple dosing regimens of both drugs in humans or constant multiples of the minimum inhibitory concentration. PK/PD parameters and PK/PD indices of the simulated dosing regimens were compared. The levofloxacin EC(50) (concentration producing 50% of the maximum effect) (mean ± standard deviation 3.57±2.16 mg/L) was higher than that for gatifloxacin (0.95±0.56 mg/L) when simulating multiple dosing regimens as well as constant concentrations (EC(50,levofloxacin)=2.75±0.45 mg/L; EC(50,gatifloxacin)=1.03±0.52 mg/L). The maximum killing rate constant (k(max)) was not statistically different for both drugs independent of fluctuating (k(max,levofloxacin)=0.40±0.19 h(-1); k(max,gatifloxacin)=0.48±0.15 h(-1)) or constant concentrations (k(max,levofloxacin)=0.34±0.06 h(-1); k(max,gatifloxacin)=0.39±0.23 h(-1)). The PK/PD model was able to describe the effect of levofloxacin and gatifloxacin against S. pneumoniae in vitro for all the simulations investigated. Gatifloxacin was more potent than levofloxacin, but both presented equivalent efficacy. The model can be used for simulating alternative regimens and optimising therapy to treat streptococcal infextions.

A novel LC-MS/MS method was developed for the quantification of vildagliptin in an aqueous matrix. The method was successfully validated, meeting all the requisites of US Food and Drug Administration guide for a bioanalytical method. The developed method presented a limit of quantification of 10 ng/mL and the range of concentration achieved was 10-1875 ng/mL. The injection volume necessary was only 10 μL, and retention time was 4.60 min. The mobile phase employed was methanol-ammonium acetate 5 mm (95:5). The stability of the drug was evaluated in the different conditions through which the samples passed. A pharmacokinetic experiment was conducted with diabetic male Wistar rats, and the concentration of drug in liver was evaluated through a microdialysis technique. The perfusion fluid employed was ultrapure water. The dose administrated was 50 mg/kg and the method allowed the quantification of vildagliptin for more than three half lives, successfully characterizing the pharmacokinetic profile when the developed method was applied. This is the first report on the tissue pharmacokinetics of a DPP-4 inhibitor and could contribute to drug dosage optimization in the future.

No abstract