Ana Maria Bergold

Development and validation of discriminating method of dissolution for fosamprenavir tablets based on in vivo data

The aim of this work is to develop and validate a dissolution test for fosamprenavir tablets (Telzir(®)) based on in vivo data. The appropriate conditions were determined after testing sink conditions in dissolution medium, rotation speed and stability of the drug. In vivo release profiles were obtained from the literature. The fraction (and percentage) of dose absorbed (FA) was calculated by deconvolution, using the Wagner-Nelson method. For this formulation, the best dissolution conditions were achieved using a USP apparatus 1 900 ml of medium containing HCl 0.01 M at a rotation speed of 75 rpm. Under these conditions a significant linear relationship between fraction of drug absorbed versus dissolved was obtained (R(2)=0.984) and a level-A IVIVC was established. The in vitro dissolution samples were analyzed using a HPLC method and the validation was performed according to USP protocol. The method showed accuracy, precision, linearity and specificity within the acceptable range. The discriminatory power of the dissolution method was challenged. The kinetics of dissolution was determined using model-dependent methods. The dissolution profiles were best described by the Hixson-Crowell model. The dissolution test was validated and could be applied to evaluate the dissolution profile of fosamprenavir tablets.

Development and validation of dissolution test for lopinavir, a poorly water-soluble drug, in soft gel capsules, based on in vivo data

The objective of the present study was to develop and validate a dissolution test for lopinavir soft gel capsules (Kaletra), using a simulated absorption profile based on in vivo data. Different conditions such as surfactant concentration, apparatus and rotation speed were evaluated. In vivo release profiles were obtained from the literature. The fraction (and percentage) of dose absorbed (FA) was calculated by using Wagner-Nelson method. The best in vitro dissolution profile was obtained using Apparatus 2 (paddle) at 25 rpm, 1000 ml of medium with 2.3% of sodium lauryl sulfate and pH 6.0. Under these conditions a level-A in vitro-in vivo correlation (IVIVC) was obtained (r = 0.997). The in vitro dissolution samples were analyzed using a HPLC method and the validation was performed according to USP protocol. The method showed accuracy, precision, linearity and specificity within the acceptable range. Both the HPLC method and the in vitro dissolution method were validated and could be used to evaluate the release profile of lopinavir soft gel capsules.

Assay of sertraline in tablets and drug substance by liquid chromatography.

A high-performance liquid chromatography isocratic procedure was developed for the assay of sertraline in drug substance and tablets. The chromatographic system consists of a RP-8 column (125 x 4 mm, 5 microm), a mobile phase composed of acetonitrile and sodium phosphate buffer, pH 5.5 (7:3), flow rate of 1.0 ml.min(-1) and UV detection at 270 nm. The method validation yielded good results. The coefficient of variation varied between 0.19 and 1.04% and accuracy of 99.18% was found. Calibration curve was linear between 0.5 and 2.5 mg x ml(-1); its correlation coefficient was 0.9999.

From Bacteria to Antineoplastic: Epothilones A Successful History

Malignancies are a major cause of morbidity and mortality worldwide. Cancer is a cell disease, characterized by a deviation of the control mechanisms of proliferation and differentiation of cells. Among the treatments available, chemotherapy is often the first choice. Epothilones are a new class of anticancer drugs that act by interacting with cellular microtubules interrupting the proliferation of cancer cells. Many synthetic and semi-synthetic analogues of epothilones have been prepared aiming improvement in effectiveness and tolerability, based on QSAR studies. These analogues have been effective for treatment of tumors resistant to first-line treatments. Six new epothilones are being subjected to clinical trials. Ixabepilone (Ixempra®) was approved by FDA in 2007, patupilone is in phase III clinical trial for ovarian and peritoneum cancer. Sagopilone, desoxiepothilone and KOS-1584 are in phase II clinical trials, for the treatment of recurrent glioblastoma and advanced metastatic breast cancer, metastasic breast cancer and metastatic pulmonary cancer, respectively. Desoxiepothilone reached only phase II trials and BMS-310705 reached phase III/IV trials, but were not approved for clinical use due to adverse effects such as neurotoxicity and severe diarrhea, which were dose-limiting. Furthermore, the low t1/2 (40h) in comparison with other class analogues, does not recommend the clinical use of this derivative. Some other synthetized epothilones presented antineoplastic activity in vitro, but are not yet submitted to clinical studies. Neuropathies and diarrhea are adverse effects presented by some substances of this class of anticancer drugs.

UV-Derivative Spectrophotometric Determination of Ritonavir Capsules and Comparison with LC Method

Abstract An ultraviolet-derivative spectrophotometric method (UV-D) has been proposed as an alternative to a previously described liquid chromatographic (LC) method for the quantitative determination of ritonavir in soft gelatin capsules. The spectrophotometric method is based on recording the second-derivative spectra for ritonavir at 222.3 nm of its solutions in methanol. The linear dynamic range was 10.0–30.0 µg · mL−1 with a correlation coefficient of 0.9995. Mean recoveries were between 99.2% and 100.2% for the tested capsules samples. Mean intra- and interassay relative standard deviations (RSDs) were less than 2.0%. The statistic analysis showed that LC and UV-D methods were equivalent to assay ritonavir capsules.

Multivariate Optimization for Extraction of Pyrethroids in Milk and Validation for GC-ECD and CG-MS/MS Analysis

A simple and inexpensive method based on solvent extraction followed by low temperature clean-up was applied for determination of seven pyrethroids residues in bovine raw milk using gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) and gas chromatography with electron-capture detector (GC-ECD). Sample extraction procedure was established through the evaluation of seven different extraction protocols, evaluated in terms of analyte recovery and cleanup efficiency. Sample preparation optimization was based on Doehlert design using fifteen runs with three different variables. Response surface methodologies and polynomial analysis were used to define the best extraction conditions. Method validation was carried out based on SANCO guide parameters and assessed by multivariate analysis. Method performance was considered satisfactory since mean recoveries were between 87% and 101% for three distinct concentrations. Accuracy and precision were lower than ±20%, and led to no significant differences (p < 0.05) between results obtained by GC-ECD and GC-MS/MS techniques. The method has been applied to routine analysis for determination of pyrethroid residues in bovine raw milk in the Brazilian National Residue Control Plan since 2013, in which a total of 50 samples were analyzed.

CHEMOMETRIC EVALUATION OF DARIFENACIN HYDROBROMIDE USING A STABILITY-INDICATING REVERSED-PHASE LC METHOD

A set of chemometric tools including in silico simulation and design of experiments (DOE) was used to develop and validate an RP-LC/UV method for darifenacin hydrobromide. Retention factor (k′) from darifenacin and resolution (R) between darifenacin and degradation product were assessed by an exploratory study using organic modifier type, organic modifier content, mobile phase pH, flow rate, and column oven temperature as factors in a full factorial 25 design. The significant factors (organic modifier content, mobile phase pH, and column oven temperature) were selected and applied in a central composite design (CCD) with axial points positioned in α = 1.681. The optimum condition was obtained with Derringers desirability. The validation was performed with a C8 (150 mm × 4.6 mm, 5 µm) column, wavelength 205 nm, 1.1 mL · min−1 flow rate, mobile phase with acetonitrile (MeCN) and orthophosphoric acid (OPA) 0.01% (v/v) pH 3.0 in a ratio 28:72 and column maintained at room temperature (25 ± 1°C). Forced decomposition was performed in agreement with the guidelines and collected data were confirmed with LC-MS/MS. The obtained k′ and R were 3.22 and 2.62, respectively. Additionally a Plackett-Burman design was done to study robustness, and the results agreed with the guideline requirements for a stability-indicating method.

A review of analytical methods for the determination of four new phosphodiesterase type 5 inhibitors in biological samples and pharmaceutical preparations

The introduction of oral phosphodiesterase type 5 inhibitor therapy in 1998 revolutionized the treatment of erectile dysfunction. Erectile dysfunction is the most common sexual problem in men. It often has a profound effect on intimate relationships and quality of life. The analysis of pharmaceuticals is an important part of the drug development process as well as for routine analysis and quality control of commercial formulations. Whereas the determination of sildenafil citrate, vardenafil and tadalafil are well documented by a variety of methods, there are few publications about the determination of udenafil, lodenafil carbonate, mirodenafil and avanafil. The paper presents a brief review of the action mechanism, adverse effects, pharmacokinetics and the most recent analytical methods that can determine drug concentration in biological matrices and pharmaceutical formulations of these four drugs.

Comparative Validation Study to Assay Milnacipran Hydrochloride in Capsules by a Stability-Indicating LC and a Second Order Derivative UV Spectroscopic Methods

A selective stability-indicating LC method and a second order derivative UV spectroscopic method (UV-D 2 ) were developed to assay milnacipran in pharmaceutical formulation. The LC method was developed with a Nucleosil C8 analytical column and a mobile phase consisting of acetonitrile, water and triethylamine (at 210 nm). The validation of UV-D 2 (zero-crossing method) was based on recording the second-derivative spectra for milnacipran hydrochloride at 268.5 nm of its solutions in 0.1 N HCl and the parameters specificity, linearity, precision, and accuracy were evaluated to both methods. The linear dynamic range was 20–100μg-mL -1 (R 2 ≥0.999). The validation data showed that both methods are reproducible, providing an accurate (98.5% to 101.6%) and precise (RSD ≤ 1.0%) quantitation of milnacipran in capsules. The methods proposed showed satisfactory results and were statistically equivalent.

Development and validation of a bioanalytical method for five antidepressants in human milk by LC–MS

The use of medications during lactation is a common practice; however, pharmacological treatments impose serious doubts to both professionals and nursing mothers regarding the safety of drugs used during this period. Most of drugs are excreted in breast milk and there is great variability in the amount of analytes that can be received by the infant. Dilemmas about breastfeeding arise most commonly in relation to postpartum depression. Depression is a major clinical problem during the postpartum period and the vulnerability to onset or recurrence of depressive symptoms increases the possibility of psychotropic drug use during lactation. Selective inhibitors of serotonin reuptake are commonly prescribed for the treatment of depressive disorders, including fluoxetine, sertraline, citalopram, and paroxetine. A validated bioanalytical method using liquid chromatography coupled to mass spectrometry was developed and validated for determination of antidepressants in human milk following protein precipation. The bioanalytical method was successfully applied to assess milk samples from nursing mothers. From found concentrations, infant absolute (4.36-12.26μg/kg/day) and relative dose (0.60-2.90%,) were estimated and low values were obtained indicating safe use during laction. However, other factors such as complemantary feeding and hepatic or renal disorders in the infant should be considered.