Solid-state evaluation and polymorphic quantification of venlafaxine hydrochloride raw materials using the Rietveld method.

Venlafaxine hydrochloride (VEN) is an antidepressant drug widely used for the treatment of depression. The purpose of this study was to carry out the preparation and solid state characterization of the pure polymorphs (Forms 1 and 2) and the polymorphic identification and quantification of four commercially-available VEN raw materials. These two polymorphic forms were obtained from different crystallization methods and characterized by X-ray Powder Diffraction (XRPD), Diffuse Reflectance Infrared Fourier Transform (DRIFT), Raman Spectroscopy (RS), liquid and solid state Nuclear Magnetic Resonance (NMR and ssNMR) spectroscopies, Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM) techniques. The main differences were observed by DSC and XRPD and the latter was chosen as the standard technique for the identification and quantification studies in combination with the Rietveld method for the commercial raw materials (VEN1-VEN4) acquired from different manufacturers. Additionally Form 1 and Form 2 can be clearly distinguished from their (13)C ssNMR spectra. Through the analysis, it was possible to conclude that VEN1 and VEN2 were composed only of Form 1, while VEN3 and VEN4 were a mixture of Forms 1 and 2. Additionally, the Rietveld refinement was successfully applied to quantify the polymorphic ratio for VEN3 and VEN4.

Morphology study of progesterone polymorphs prepared by polymer-induced heteronucleation (PIHn).

In this article, morphology of progesterone polymorphs prepared by polymer-induced heteronucleation (PIHn) technique was studied. Hydroxypropyl methylcellulose(HPMC), such as dextran T-500 and gelatin G-9382, polyisoprene (PI), and acrylonitrile/butadiene copolymer (NBR) were used as substrates. The crystallizations were performed by solvent evaporation at room temperature from 0.5, 10, and 40 mg/ml solutions in chloroform and acetone. Progesterone polymorphs were identified by X-ray diffraction. Differential scanning calorimetry and total attenuated reflectance infrared spectroscopy were used as complementary techniques in the identification. Depending on the polymeric matrix and the concentration used, form 1, form 2, or mixture of both polymorphs were obtained. Scanning electron microscopy pictures evidenced difference in morphology and in homogeneity of the two progesterone polymorphs. These polymorphs prepared by PIHn, did not present a distinctive morphology that allows identifying polymorph by its crystal habit. Hence, polymeric matrix induced the crystallization, affecting polymorphism and morphology.

Determination of nimodipine in the presence of its degradation products and overall kinetics through a stability-indicating LC method.

The determination of nimodipine in the presence of its degradation products, formed through photolysis, acidic and alkaline hydrolysis, and the drug degradation kinetics under these conditions, was investigated through a validated liquid chromatography method. Separation was achieved using a Phenomenex Luna C18 column (250 × 4.6 mm i.d., 5 µm) with a mobile phase consisting of acetonitrile-methanol-water (55:11:34, v/v/v), at 0.5 mL/min and with ultraviolet detection at 235 nm. The method was considered to be specific, accurate, precise, robust and linear over the concentration range of 5.0 to 35.0 µg/mL. The drug followed a first-order reaction for both hydrolysis and photolysis in methanol, and zero-order for photolysis in acetonitrile and water. The calculated activation energies were 10.899 and 23.442 kcal/mol for alkaline and acidic hydrolysis, respectively. No degradation was observed under thermal and oxidative stress conditions.

Solid-state characterization and dissolution properties of Fluvastatin sodium salt hydrates.

The present study reports the solid-state properties of Fluvastatin sodium salt crystallized from different solvents for comparison with crystalline forms of the commercially available raw material and United States Pharmacopeia (USP) reference standard. Fluvastatin (FLV) samples were characterized by several techniques; such as X-ray powder diffractometry, differential scanning calorimetry, thermogravimetry, liquid and solid-state nuclear magnetic resonance spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, and scanning electron microscopy. In addition, intrinsic dissolution rate (IDR) of samples was performed in order to study the influence of crystalline form and other factors on rate and extent of dissolution. Three different forms were found. The commercial raw material and Fluvastatin-Acetonitrile (ACN) were identified as "form I" hydrate, the USP reference standard as "form II" hydrate and an ethanol solvate which presented a mixture of phases. Form I, with water content of 4%, was identified as monohydrate.

High-performance column liquid chromatographic method for the simultaneous determination of buclizine, tryptophan, pyridoxine, and cyanocobalamin in tablets and oral suspension.

An HPLC method was developed and validated for the simultaneous determination of buclizine, tryptophan, pyridoxine, and cyanocobalamin in pharmaceutical formulations. The chromatographic separation was carried out on an RP-C18 column using a mobile phase gradient of methanol, 0.015 M phosphate buffer (pH 3.0), and 0.03 M phosphoric acid at a flow rate of 1.0 mL/min and UV detection at 230, 280, and 360 nm, respectively, for buclizine, tryptophan, pyridoxine, and cyanocobalamin. The method validation yielded good results with respect to linearity (r>0.999), specificity, precision, accuracy, and robustness. The RSD values for intraday and interday precision were below 1.82 and 0.63%, respectively, and recoveries ranged from 98.11 to 101.95%. The method was successfully applied for the QC analysis of buclizine, tryptophan, pyridoxine, and cyanocobalamin in tablets and oral suspension.

Liquid chromatographic determination of norfloxacin in extended-release tablets.

A stability indicating reversed-phase liquid chromatography method is developed and validated for the determination of norfloxacin in a new formulation of extended-release tablets. The LC method is carried out on a Luna C(18) column (150 x 4.6 mm) maintained at 40 degrees C. The mobile phase is composed of phosphate buffer (0.04 M, pH 3.0)-acetonitrile (84:16, v/v) run at a flow rate of 1.0 mL/min and detection at 272 nm. The chromatographic separation was obtained within 10 min, and it is linear in the concentration range of 0.05-5 microg/mL. Validation parameters, such as the specificity, linearity, precision, accuracy, and robustness, were evaluated, and results were within the acceptable range. Moreover, the proposed method was successfully applied for the assay of norfloxacin in the developed formulations.

Development and validation of a stability-indicating LC method for the determination of venlafaxine in extended-release capsules and dissolution kinetic studies.

A stability-indicating reversed-phase high-performance liquid chromatography method is developed and validated for the determination of venlafaxine hydrochloride (VEN) in extended-release capsules containing spherical beads and for dissolution studies. The method is carried out on a Luna C(18) column (250 mm x 4.6 mm) maintained at 35 degrees C. The mobile phase is composed of ammonium-acetate buffer 32 mM, adjusted to pH 6.8 with phosphoric acid-acetonitrile-methanol (62:30:8, v/v/v), run at a flow rate of 1.0 mL/min, and detection at 226 nm. Validation parameters such as the specificity, linearity, precision, accuracy, and robustness are evaluated, giving results within the acceptable range. In order to evaluate the best dissolution condition, the dissolution profiles are performed under different conditions, such as media (HCl, water, phosphate buffer), apparatus (I and II), and dissolution rates (50, 75, and 100 rpm). The kinetics release mechanism is evaluated by fitting different models, such as the zero order rate, first order, and Higuchi. Moreover, the proposed method is successfully applied for the assay of VEN in extended-release capsules.

Liquid chromatographic determination of cetirizine in oral formulations.

The development and validation of a reversed-phase liquid chromatographic (LC) method for the determination of cetirizine dihydrochloride in oral formulations are described. An isocratic LC analysis was performed on a reversed-phase C18 column (250 x 4.6 mm id, 5 microm particle size). The mobile phase was 1% orthophosphoric acid solution, pH 3.0-acetonitrile (60 + 40, v/v), pumped at a constant flow rate of 1.0 mL/min. Measurements were made at a wavelength of 232 nm. The calibration curves were linear over the range of 10-30 microg/mL (r2 = 0.9999). The relative standard deviation (RSD) values for intraday precision were 0.94 and 1.43% for tablets and compounded capsules, respectively. The RSD values for interday precision were 0.13 and 0.82% for tablets and compounded capsules, respectively. Recoveries ranged from 97.7 to 101.8% for tablets and from 98.4 to 102% for compounded capsules. No interferences from the excipients were observed. Because of its simplicity and accuracy, the method is suitable for routine quality-control analysis for cetirizine in tablets and compounded capsules.

Determination of omeprazole in bulk and injectable preparations by liquid chromatography.

An accurate, simple, reproducible, and sensitive liquid chromatographic method was developed and validated for the determination of omeprazole in powder for injection and in pellets. The analyses were performed at room temperature on a reversed-phase C18 column of 250 x 4.6 mm id, 5 microm particle size. The mobile phase, composed of methanol-water (90 + 10, v/v), was pumped at a constant flow rate of 1.5 mL/min. Detection was performed on a UV detector at 301 nm. The method was validated in terms of linearity, precision, accuracy, and ruggedness. The response was linear in the range 32-48 microg/mL (r2 = 0.9976). The relative standard deviation values for intra- and interday precision studies were 1.22 and 1.56% for injectable and 2.13 and 2.45% for pellets, respectively. Recoveries ranged between 95.81 and 100.48%.