Mucoadhesive gellan gum hydrogel containing diphenyl diselenide-loaded nanocapsules presents improved anti-candida action in a mouse model of vulvovaginal candidiasis.

The aim of this study was to evaluate the in vitro antifungal action of a diphenyl diselenide-loaded poly(ε-caprolactone) nanocapsules suspension (NC-1) and incorporate it into a gellan gum hydrogel formulation in order to assess its in vivo efficacy in an animal model of vulvovaginal candidiasis. Nanocapsules suspensions containing the compound (NC-1 ∼ 5 mg/mL) or not (NC-B) were prepared by the interfacial deposition of preformed polymer method. To estimate in vitro antifungal effect, the broth microdilution test was applied. The results showed that NC-1 had equal or lower MIC values when compared to free compound against fifteen Candida strains. Following, the hydrogel was prepared by direct thickening of the nanocapsules suspension by gellan gum addition. The animal model of vulvovaginal candidiasis was induced by infecting female Swiss mice with Candida albicans strains. The animals were topically treated with 20 µL of hydrogels (NC-1 and free compound - 0.1 mg of diphenyl diselenide/once a day for seven days) and then the total fungal burden was assessed after the euthanasia. The results showed that the hydrogels presented pH in the acidic range, compound content close to theoretical value, homogeneous particle distribution with nanometric size, high physicochemical and microbiological stability as well as great bioadhesive property. The nano-based presented superior pharmacological action in comparison to the hydrogel containing non-encapsulated diphenyl diselenide. The results demonstrated that the nanoencapsulation maintained the effective antifungal action of diphenyl diselenide. The nano-based hydrogel formulation may be considered a promising approach against vulvovaginal candidiasis.

Development of doxycycline hyclate suppositories and pharmacokinetic study in rabbits.

Doxycycline hiclate is a broad spectrum antibiotic widely used in human and veterinary medicine. The inability to perform the parenteral administration of drugs and the lack of oral preparations can be mentioned as difficulties in the treatment of animals in the domestic environment. In this scenario, the aim of this study was to investigate the bioavailability of the drug by rectal route, to propose a potential suppository formulation containing 25 mg of doxycycline as an alternative to the available injectable formulations. Hydrophilic and lipophilic suppositories were prepared, in polyethylene glycol (S-PEG) or cocoa butter (S-CBT), respectively. The suppositories were prepared and evaluated concerning visual characteristics, content, average weight, melting range, content uniformity and in vitro release. A stability study was performed and the two most stable formulations were submitted to a pharmacokinetic study in rabbits. The bioavailability of the suppositories was compared to the data of the intravenous (i.v.) formulation. PEG suppository showed 49.13% bioavailability and CBT 51.43% with Cmax equal to 2.06 ±â€¯2.96 µg.mL-1 and 1.54 ±â€¯0.28 µg.mL-1, respectively. The data obtained suggest that rectal administration may become another method of administration of doxycycline in the treatment of bacterial infections.

Population pharmacokinetic modeling to establish the role of P-glycoprotein on ciprofloxacin distribution to lung and prostate following intravenous and intratracheal administration to Wistar rats.

Ciprofloxacin (CIP) is indicated for clinical treatment of urinary and respiratory tract infections. Poor infection site penetration and consequent insufficient exposure to the antimicrobial agent may be the reason for some therapeutic failures. Ciprofloxacin is reported as a substrate for efflux transporters, such as P-glycoprotein, which could be related to the presence of sub-therapeutic drug concentration at the infection site. In the present work we evaluated CIP pharmacokinetics (PK) in plasma and lung and prostate tissues of Wistar rats after intravenous (i.v.) and intratracheal (i.t.) dosing (7 mg/Kg) in the presence and absence of P-gp inhibitor tariquidar (TAR, 15 mg/Kg). Microdialysis was applied to determine free tissue concentration-time profiles and the obtained data were analyzed by non-compartmental and population PK (popPK) analysis. A sequential strategy was used to develop the popPK model: characterization of CIP PK in tissues (Tissue model) was performed subsequently to CIP PK modeling in plasma (Plasma model). Two and three compartmental models were used to simultaneously characterize plasma concentrations after i.t. and i.v. dosing; the distribution model was developed by separating the central compartment into venous and arterial compartment and by adding lung and prostate; TAR was identified as a significant covariate for clearance and volume of distribution of central compartment as well as for inter-compartmental clearance. Our results indicate an impact of P-gp on plasma PK, likely by acting on renal active secretion of CIP. Regarding CIP exposure in lung and prostate tissues, our results suggest a complex interplay between drug transporters; P-gp inhibition by TAR was likely counterbalanced by the activity of other efflux/influx transporters, which could not be fully characterized by our model.

Pharmacokinetics of hERG Channel Blocking Voacangine in Wistar Rats Applying a Validated LC-ESI-MS/MS Method.

Herbal preparations from Voacanga africana are used in West and Central African folk medicine and are also becoming increasingly popular as a legal high in Europe. Recently, the main alkaloid voacangine was found to be a potent human ether-à-go-go-related gene channel blocker in vitro. Blockage of this channel might imply possible cardiotoxicity. Therefore, the aim of this study was to characterise voacangine in vivo to assess its pharmacokinetics and to estimate if further studies to investigate its cardiotoxic risk are required. Male Wistar rats received different doses of voacangine as a pure compound and as a hydro-ethanolic extract of V. africana root bark with a quantified amount of 9.71 % voacangine. For the obtained data, a simultaneous population pharmacokinetics model was successfully developed, comprising a two-compartment model for i. v. dosing and a one-compartmental model with two first-order absorption rates for oral dosing. The absolute bioavailability of voacangine was determined to be 11-13 %. Model analysis showed significant differences in the first absorption rate constant for voacangine administered as a pure compound and voacangine from the extract of V. africana. Taking into account the obtained low bioavailability of voacangine, its cardiotoxic risk might be neglectable in healthy consumers, but may have a serious impact in light of drug/drug interactions and impaired health conditions.

Simultaneous Semimechanistic Population Analyses of Levofloxacin in Plasma, Lung, and Prostate To Describe the Influence of Efflux Transporters on Drug Distribution following Intravenous and Intratracheal Administration.

Levofloxacin (LEV) is a broad-spectrum fluoroquinolone used to treat pneumonia, urinary tract infections, chronic bacterial bronchitis, and prostatitis. Efflux transporters, primarily P-glycoprotein (P-gp), are involved in LEV's tissue penetration. In the present work, LEV free lung and prostate interstitial space fluid (ISF) concentrations were evaluated by microdialysis in Wistar rats after intravenous (i.v.) and intratracheal (i.t.) administration (7 mg/kg of body weight) with and without coadministration of the P-gp inhibitor tariquidar (TAR; 15 mg/kg administered i.v.). Plasma and tissue concentration/time profiles were evaluated by noncompartmental analysis (NCA) and population pharmacokinetics (popPK) analysis. The NCA showed significant differences in bioavailability (F) for the control group (0.4) and the TAR group (0.86) after i.t. administration. A four-compartment model simultaneously characterized total plasma and free lung (compartment 2) and prostate (compartment 3) ISF concentrations. Statistically significant differences in lung and prostate average ISF concentrations and levels of kidney active secretion in the TAR group from those measured for the control group (LEV alone) were observed. The estimated population means were as follows: volume of the central compartment (V1), 0.321 liters; total plasma clearance (CL), 0.220 liters/h; TAR plasma clearance (CLTAR), 0.180 liters/h. The intercompartmental distribution rate constants (K values) were as follows: K12, 8.826 h(-1); K21, 7.271 h(-1); K13, 0.047 h(-1); K31, 7.738 h(-1); K14, 0.908 h(-1); K41, 0.409 h(-1); K21 lung TAR (K21LTAR), 8.883 h(-1); K31 prostate TAR (K31PTAR), 4.377 h(-1). The presence of P-gp considerably impacted the active renal secretion of LEV but had only a minor impact on the efflux from the lung following intratracheal dosing. Our results strongly support the idea of a role of efflux transporters other than P-gp contributing to LEV's tissue penetration into the prostrate.

Validation of a sensitive HPLC/fluorescence method for assessment of ciprofloxacin levels in plasma and prostate microdialysate samples from rats.

Chronic bacterial prostatitis treatment consists of broad-spectrum antibiotic therapy for long periods of time. Drug penetration into the prostate makes the treatment a challenged. Ciprofloxacin is one of the most prescribed drugs for this treatment. A liquid chromatography with fluorescence detection method was developed and validated for determining ciprofloxacin concentrations in two different matrices: plasma and prostate microdialysate. Ciprofloxacin was separated on a C18 column eluted with a mobile phase constituted of a mixture of 0.4% aqueous triethylamine:methanol:acetonitrile (75:15:10, v/v/v) and 0.4% aqueous triethylamine:acetonitrile (88:12, v/v) for microdialysate and plasma samples, respectively. Linearity was obtained over a concentration range of 5-1000 ng/mL (microdialysate) and 10-2000 ng/mL (plasma), with coefficients of determination ≥0.9956. Precision was determined from the analysis of six quality control samples and showed RSD values <11.1 and 7.4% for intra and inter-assay precision, respectively. The accuracy ranged from 85.6 to 114.3%. The method was applied to a preliminary pharmacokinetic study to investigate ciprofloxacin concentrations in prostate, sampled by microdialysis, and plasma after a 7 mg/kg intravenous dose to Wistar rats. The method showed high sensitivity using only protein precipitation as plasma sample clean-up and was successfully applied to investigate ciprofloxacin prostate penetration.

Development and validation of a stability-indicating size-indicating size-exclusion LC method for the determination of rhIFN-alpha2a in pharmaceutical formulations.

A size-exclusion LC method was validated for the determination of interferon-a2a (rhlFN-alpha2a) in pharmaceutical formulations without interference from human serum albumin. Chromatographic separation was performed on a BioSep-SEC-S 2000 column (300 x 7.8 mm id). The mobile phase consisted of 0.001 M monobasic potassium phosphate, 0.008 M sodium phosphate dibasic; 0.2 M sodium chloride buffer, pH 7.4, run at a gradient flow rate and using photodiode array detection at 214 nm, was used. Chromatographic separation was achieved with a retention time of 17.2 min, and the analysis was linear over the concentration range of 1.98 to 198 microg/mL (r2 = 0.9996). The accuracy was 101.39%, with bias lower than 1.67%. The LOD and LOQ were 0.87 and 1.98 microg/mL, respectively. Moreover, method validation demonstrated acceptable results for precision and robustness. The method was applied to the assessment of rhlFN-alpha2a and related proteins in biopharmaceutical dosage forms, and the content/potencies were correlated to those given by a validated RP-LC method and an in vitro bioassay. It was concluded that use of the methods in conjunction allows a great improvement in monitoring stability and QC, thereby ensuring the therapeutic efficacy of the biotechnology-derived medicine.

Uncaria tomentosa stimulates the proliferation of myeloid progenitor cells.

ETHNOPHARMACOLOGICAL RELEVANCE: The Asháninkas, indigenous people of Peru, use cat's claw (Uncaria tomentosa) to restore health. Uncaria tomentosa has antioxidant activity and works as an agent to repair DNA damage. It causes different effects on cell proliferation depending on the cell type involved; specifically, it can stimulate the proliferation of myeloid progenitors and cause apoptosis of neoplastic cells. Neutropenia is the most common collateral effect of chemotherapy. For patients undergoing cancer treatment, the administration of a drug that stimulates the proliferation of healthy hematopoietic tissue cells is very desirable. It is important to assess the acute effects of Uncaria tomentosa on granulocyte-macrophage colony-forming cells (CFU-GM) and in the recovery of neutrophils after chemotherapy-induced neutropenia, by establishing the correlation with filgrastim (rhG-CSF) treatment to evaluate its possible use in clinical oncology. MATERIALS AND METHODS: The in vivo assay was performed in ifosfamide-treated mice receiving oral doses of 5 and 15 mg of Uncaria tomentosa and intraperitoneal doses of 3 and 9 µg of filgrastim, respectively, for four days. Colony-forming cell (CFC) assays were performed with human hematopoietic stem/precursor cells (hHSPCs) obtained from umbilical cord blood (UCB). RESULTS: Bioassays showed that treatment with Uncaria tomentosa significantly increased the neutrophil count, and a potency of 85.2% was calculated in relation to filgrastim at the corresponding doses tested. An in vitro CFC assay showed an increase in CFU-GM size and mixed colonies (CFU-GEMM) size at the final concentrations of 100 and 200 µg extract/mL. CONCLUSIONS: At the tested doses, Uncaria tomentosa had a positive effect on myeloid progenitor number and is promising for use with chemotherapy to minimize the adverse effects of this treatment. These results support the belief of the Asháninkas, who have classified Uncaria tomentosa as a 'powerful plant'.

HPLC determination of bezafibrate in human plasma and its application to pharmacokinetics studies.

An isocratic high-performance liquid chromatographic (HPLC) method was developed and validated for the determination of bezafibrate in biological fluids. Bezafibrate was separated on a C(18) analytical column (150 x 4.6 mm i.d., 5 microm particle size) with 0.01 M phosphate buffer (pH 3.5)-acetonitrile-methanol (50:40:10) as mobile phase at a flow rate of 1.0 mL/min. The UV detector was set to 230 nm. Bezafibrate was extracted from human plasma using a simple liquid-liquid extraction with tert-butyl methyl ether. Parameters such as linearity, precision, accuracy, recovery, specificity, and stability were evaluated by method validation studies. All the parameters remained within acceptable limits. The validated procedure was linear in the concentration range of 0.2-50 microg/mL. The proposed method used for individual drug determinations is applicable for therapeutic monitoring purposes as well as for use in pharmacokinetic investigations. As an example, the practical quantification limit for bezafibrate in plasma was about 0.05 microg/mL with precision of 10.2% and accuracy of 112.6%. The method was applied in a study of the pharmacokinetics of bezafibrate in six healthy volunteers, who ingested a single oral dose of 200 mg.

Development and validation of a capillary zone electrophoresis method for assessment of recombinant human granulocyte colony-stimulating factor in pharmaceutical formulations and its correlation with liquid chromatography methods and bioassay.

A capillary zone electrophoresis (CZE) method was validated for the analysis of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and performed on a fused-silica capillary, with detection at 195 nm. The background electrolyte solution consisted of 50 mM sodium tetraborate solution at pH 9. The method was linear in the concentration range of 1-200 microg/mL and the limit of quantitation (LOQ) was 1 microg/mL, with acceptable validation parameters. The method was applied for the analysis of pharmaceutical formulations, and the results were correlated to the reversed-phase HPLC method (RP-HPLC), size-exclusion HPLC method (SE-HPLC) and in vitro bioassay method.