Synthesis, characterization and enzyme inhibitory activity of new pyrazinamide iron complexes.

The present paper deals with synthesis, characterization and amylase inhibitory activity of pyrazinamide (PYZ) with iron in its both (II) and (III) oxidation states. The synthesized complexes were characterized on the basis of IR, UV, 1H-NMR, 13C-NMR, elemental analysis and SEM. Changes in IR data shows that PYZ form complex with octahedral geometry and binding sites are ring nitrogen and carbonyl group, wherein two sides are satisfied with two chloride ions. SEM images indicate the crystalline state and surface morphology of PYZ and its complexes. Elemental analysis proves the composition of complexes. Pyrazinamide and the complexes showed no significant effect on amylase activity but the activity was inhibited in the presence of ferrous chloride.

Facile LC-UV methods for simultaneous monitoring of ciprofloxacin and rosuvastatin in API, formulations and human serum.

An efficient, selective and cost-effective liquid chromatographic assay was developed and validated for the simultaneous quantification of ciprofloxacin and rosuvastatin in Active Pharmaceutical Ingredients (API), pharmaceutical formulations and in human serum. The chromatographic system consisted of mobile phase methanol-water, 90:10 v/v at pH 3.0 adjusted with o-phosphoric acid, pumped at 1.0 mL/min through a prepacked Purospher Star C18 (5 µm, 25 × 0.46 cm) column and effluent was monitored at the isosbestic point (255 nm) as well as at the λmax of individual drugs (243 and 271 nm). The method was validated over a linear concentration range of 0.25-15 µg/mL for ciprofloxacin and 0.33-20 µg/mL for rosuvastatin (r(2) ≥ 0.999). The ranges of reliable response (limits of detection and quantitation) for ciprofloxacin were 3-15 and 9-45 ng/mL and 17-29 and 52-88 ng/mL, respectively, for rosuvastatin in all API, pharmaceutical formulations and human serum. Analytical recovery from human serum was >98% and relative standard deviation (RSD) was <2. The accuracies were 97.13-102.55 and 97.41-101.31% and precisions in RSD were 0.04-1.90 and 0.02-1.23% for ciprofloxacin and rosuvastatin, respectively. No matrix interferences, ion suppression/enhancement and carry-over were detected. The total assay run time was less than 5 min. In another study, for optimum performance the detector was programmed for multiwavelength scanning at the absorption maxima of each component. Consequently, the linearity range was improved and limit of detection and quantitation values were down to 1-4 and 4-12 ng/mL for ciprofloxacin and 3-5 and 9-15 ng/mL for rosuvastatin, respectively. The validation parameters fitted ICH guidelines through the isosbestic and individual λmax approach. The small sample volume and simplicity of preparation make this method suitable for use in human serum samples, pharmaceutical formulations, quality control, drug-drug interaction studies, clinical laboratories, drug research centers and forensic medical centers.

Liquid chromatographic method for the simultaneous determination of captopril, piroxicam, and amlodipine in bulk drug, pharmaceutical formulation, and human serum by programming the detector.

A highly sensitive LC method with UV detection has been developed for the simultaneous determination of coadministered drugs captopril, piroxicam, and amlodipine in bulk drug, pharmaceutical formulations, and human serum at the isosbestic point (235 nm) and at individual λmax (220, 255, and 238 nm, respectively) by programming the detector with time to match the individual analyte's chromophore, which enhanced the sensitivity with linear range. The assay involved an isocratic elution of analytes on a Bondapak C18 (10 µm, 25 × 0.46 cm) column at ambient temperature using a mobile phase of methanol/water 80:20 at pH 2.9 and a flow rate of 1.0 mL/min. Linearity was found to be 0.25-25, 0.10-6.0, and 0.20-13.0 µg/mL with correlation coefficient >0.998 and detection limits of 7.39, 3.90, and 9.38 ng/mL, respectively, whereas calibration curves for wavelength-programmed analysis were 0.10-6.0, 0.04-2.56, and 0.10-10.0 µg/mL with correlation coefficient >0.998 and detection limits of 5.79, 2.68, and 3.87 ng/mL, respectively. All the validated parameters were in the acceptable range. The recovery of drugs was 99.32-100.39 and 98.65-101.96% in pharmaceutical formulation and human serum, respectively, at the isosbestic point and at individual λmax . This method is applicable for the analysis of drugs in bulk drug, tablets, serum, and in clinical samples without interference of excipients or endogenous serum components.

RP-LC method for the simultaneous determination of gliquidone, pioglitazone hydrochloride, and atorvastatin in formulations and human serum.

The objective of this research was to develop and validate a rapid, economical, and sensitive HPLC method for quantitative determination of gliquidone, pioglitazone hydrochloride, and atorvastatin in tablets and serum. Due to drug combination of these formulations, there has been a need for a reliable quantitative method to determine these drugs in commercial samples and human serum. The chromatographic separation was carried out at ambient temperature with a mobile phase consisting of methanol-water (90 + 10, v/v), with pH adjusted to 3.50 with phosphoric acid. The pump was operated at a flow rate of 1 mL/min, and all analytes were detected at 235 nm. The method was linear over the concentration range of 5-50 microg/mL for all the drugs. The LOD of gliquidone, pioglitazone hydrochloride, and atorvastatin was 0.30, 1.30, and 0.57 microg/mL and LOQ was 0.98, 4.28, and 1.90 microg/mL, respectively. The proposed method was successfully applied to the determination of these drugs in commercial tablets and human serum. The established method was validated with respect to specificity, linearity, precision, accuracy, and ruggedness.

Development and validation of stability-indicating HPLC method for the simultaneous determination of paracetamol, tizanidine, and diclofenac in pharmaceuticals and human serum.

A method is described for the simultaneous determination of paracetamol, tizanidine, and diclofenac in mixtures. The method was based on HPLC separation of the three drugs followed by UV detection at 254 nm. The separation was carried out on a Hypersil ODS, C18 (250 x 4.6 mm id, 10 microm particle size) column using the mobile phase aqueous 0.2% ammonium carbonate-methanol (60 + 40, v/v) at a flow rate of 1 mL/min. The linear regression analysis data were used for the regression curve in the range of 170-10 000 ng/mL for paracetamol, 120-10 000 ng/mL for tizanidine, and 20-10 000 ng/mL for diclofenac. No chromatographic interference from tablet excipients was found. In order to check the selectivity of the proposed method, degradation studies were carried out using hydrolysis (acid, basic, and neutral), thermolysis, and oxidation. The developed method, after being validated in terms of precision, robustness, recovery, LOD, and LOQ, was successively applied to the analysis of pharmaceutical formulations and human serum.

Cleaning validation of ofloxacin on pharmaceutical manufacturing equipment and validation of desired HPLC method.

Inadequate cleaning of a pharmaceutical manufacturing plant or inadequate purging of the individual pieces of equipment used in multi-product manufacturing or equipment not dedicated to individual products may lead to contamination of the next batch of pharmaceutics manufactured using the same equipment. Challenges for cleaning validation are encountered especially when developing sensitive analytical methods capable of detecting traces of active pharmaceutical ingredients that are likely to remain on the surface of the pharmaceutical equipment after cleaning. A method's inability to detect some residuals could mean that either the method is not sensitive enough to the residue in question or the sampling procedure is inadequate. A sensitive and reproducible reversed-phase, high-performance liquid chromatographic method was developed for the determination of ofloxacin in swab samples. The method for determining ofloxacin residues on manufacturing equipment surfaces was validated in regard to precision, linearity, accuracy, specificity, limit of quantification, and percent recovery from the equipment surface, as well as the stability of a potential contaminant in a cleaning validation process. The active compound was selectively quantified in a sample matrix and swab material in amounts as low as 0.55 ng/mL. The swabbing procedure using cotton swabs was validated. A mean recovery from stainless steel plate of close to 85% was obtained. Chromatography was carried out on a pre-packed Merck (Dermstadt, Germany) Lichrospher model 100 Rp-18 (5.0 microm, 250 mm X 4.0 mm) column using a mixture of sodium lauryl sulfate (0.024% aqueous solution), acetonitrile, and glacial acetic acid (500:480:20,v/v) as the mobile phase at a flow rate of 1.5 mL/min with a column temperature of 35 degrees C and 294 nm detection. The assay was linear over the concentration range of 2 ng/mL to 2000 ng/mL (R approximately 0.99998). The method was validated for accuracy and precision. The stability of ofloxacin in the swab samples was also assessed. In regard to the 10-ppm acceptance criteria in the succeeding batch, the calculated limit was 437 microg/cm2 while according to the 0.1% dosing approach the calculated value was 116 microg/cm2. The calculated recovery values from swab samples were below these acceptable limits during three consecutive cleaning trials. This confirms that the desired level of cleanliness is achieved using the current cleaning procedures, which were consequently validated.

In vitro interactions of captopril with H2-receptor antagonists.

Captopril is effective in the treatment of hypertension of all grades of severity. H2-receptors antagonists block gastric acid secretion and some cardiovascular effects of histamine. In view of the fact that, simultaneous administration of both drugs may alter the antihypertensive effect of captopril, present paper deals with the in vitro availability studies of captopril in presence of commonly used H2-receptor antagonists like cimetidine, ranitidine and famotidine. In order to simulate various pH levels in GI tract and to find out the kinetics and energetics of captopril-H2-receptor antagonist interactions, these studies were carried out in buffers of pH 4, 7.4 and 9 at 37 degrees C and at elevated temperatures. These studies clearly indicate that most of the H2-receptor antagonists bind to captopril, forming charge-transfer complexes. As a result, the availability of captopril was affected by the concurrent administration of H2-receptor antagonists. Accordingly coadministration of both the drugs should be avoided.

Fosinopril H(2)-receptor antagonists interaction studies by derivative spectroscopy.

Fosinopril sodium, a phosphinic acid derivative is an angiotensin converting enzyme (ACE) inhibitor, which had been employed for the treatment of hypertension and congestive heart failure; long tem use of ACE inhibitor often result in stress ulcers due to which H(2) receptor antagonists are also concurrently prescribed. The later compete with histamine for H(2) receptors and block gastric acid secretion and some cardiovascular effects of histamine. Our studies are focused on the in vitro availability of fosinopril in presence of commonly used H(2) receptor antagonists. Derivative spectroscopy has been employed for the quantitation of fosinopril and H(2) receptor antagonists followed by linear regression analysis. These studies were carried out in buffers of pH 7.4 and 9 at 37, 48 and 60( masculine)C. Stability constant and thermodynamic function had also been calculated in order to evaluate the reaction mechanism. Commonly prescribed H(2) receptor antagonists like cimetidine, ranitidine and famotidine were used in these studies. Present study clearly indicated that most of the H(2) receptor antagonists studied decreased the availability of fosinopril which conclude that availability of fosinopril can be affected by the concurrent administration of H(2) receptor antagonists.

In vitro availability of ofloxacin in presence of metals essential to human body.

The significance of interaction between ofloxacin and metals ions was evaluated in this study. The absorption of ofloxacin can be negatively affected by concomitant administration of agents containing metal cations. Current studies examine alterations of ofloxacin availability by metal cations and is limited to conventional metal-containing agents such as antacids and mineral supplements. The in vitro availability of ofloxacin was studied in presence of metal ions as magnesium, calcium, chromium, manganese, ferric, ferrous, cobalt, nickel, copper, zinc and cadmium in their salt form in simulated gastric juice, buffers of pH 7.4 and 9 at 37 degrees C by using a modified B.P 2002 dissolution apparatus. UV/VIS (Shimadzu 1601) spectrophotometer was used to analyze the drug by measuring absorbance at 294 nm in simulated gastric juice and at 288 nm in pH 7.4 and 9. The result showed that availability of ofloxacin slightly changed in presence of all metals in all these dissolution mediums.

A validated method for the analysis of diltiazem in raw materials and pharmaceutical formulations by rp-HPLC.

A simple, selective and rapid reversed phase high performance liquid chromatographic (HPLC) method for the analysis of diltiazem (DTZ) in bulk material and pharmaceutical formulations has been developed and validated. Sample was resolved on a Hypersil, ODS, C-18(150x4.6 mm, 5 micron) column. The mobile phase consisted of methanol-water (80:20 v/v, pH 3.1 adjusted with phosphoric acid) was delivered at a flow rate of 0.5 ml/min at ambient temperature and the retention time was about 2.6 minutes with symmetrical peaks. Studies were performed on an HPLC system equipped with a UV/visible detector at 236 nm. Flurbiprofen (FLR) was used as an internal standard. The developed method gave good resolution between diltiazem and internal standard. The method is specific to DTZ and able to resolve the drug peak from formulation excepients. The calibration curve was linear over the concentration range of 0.195-50 mg/ml (R2=0.999). The proposed method is accurate (the accuracy results were 94.1-99.39 for diltiazem recoveries), precise (The intraday and interday precision CVs were 0.035-2.2 %) and linear within the desired range. The lower limits of detection for DTZ was found to be 0.0184 microg/ml and the quantitation limit was about 0.056 microg/ml and therefore could be employed as a more convenient and efficient option for the analysis of diltiazem and its related compounds in drug substance and formulations.

In vitro activity of cefadroxil, cephalexin, cefatrizine and cefpirome in presence of essential and trace elements.

Evidences supporting the introduction of metallic elements in several biological processes are rapidly accumulating. Likewise, many drugs possess modified toxicological and pharmacological properties when in the form of metal complexes. In order to ascertain the role of various essential and trace element complexation on the antibacterial activity of various cephalosporins, the synergistic or antagonistic behavior of cefadroxil, cephalexin, cefatrizine and cefpirome in presence of essential and trace elements has been studied and compared with the parent drug. The essential and trace elements comprised of magnesium, calcium, chromium, manganese, ferric, cobalt, nickel, copper, zinc and cadmium in the form of their chloride. These studies were carried out by observing the minimum inhibitory concentration (MIC) using agar dilution method and compared with the MIC'S of the standard cephalosporins against various species of Gram (+) and Gram (-) microorganisms such as Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus faecalis, Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhi and Shigella dysenteriae. Different dilutions of cephalosporins and salts of essential and trace elements were used in these studies. The ratio of the drug and metal salts was 1:1 and the reactions were carried out at two different temperatures as 37 degrees C and 60 degrees C in order to study the complex formation. The aim of our study was on one hand to evaluate the changes in microbiological activity of the standard cephalosporins after in vitro metal interactions to study the synergetic or antagonistic behavior of the later through the difference in MICs values of these cephalosporins and on the other hand to access the bioassay directed extent of drug metal complexations. Our investigation reveal that interaction of above cephalosporins with essential and trace elements cause antagonistic effect in many cases which was shown by decrease in antimicrobial activity of cephalosporins and MIC values were increased.

Review: nanoparticles in delivery of cardiovascular drugs.

Everything in nature is built upward from the atomic level to define limits and structures to everything. Nanomedicines marked the field of medicine from nanobiotechnology, biological micro-electromechanical systems, microfluidics, biosensors, drug delivery, microarrays to tissue microengineering. Since then nanoparticles has overcome many challenges from blood brain barrier to targeting tumors. Where solid biodegradable nanoparticles were a step up liposome, targeting nanoparticles opened a whole new field for drug delivery. In this article, we attempt to discuss how the pioneered technique is serving in the drug delivery to cardiovascular system and how with the manipulation of their properties, nanoparticles can be made to fulfill desired function. Also how nanocarriers are improving molecular imaging to help improve diagnosis and treatment of cardiovascular disease is focused in this article.

Cephradine antacids interaction studies.

The present work comprises of interaction studies of cephradine with antacids. Cephradine is included among the first generation cephalosporin, which is active against a wide range of Gram positive and Gram-negative bacteria including penicillinase-producing staphylococci. Since the presence of complexing ligand may affect the bioavailability of a drug in blood or tissues, therefore, in order to study the probable interaction of cephradine with antacids all the reaction conditions were simulated to natural environments. Antacids are commonly used in patients complaining of GI irritations. The behavior of cephradine in presence of seven antacids i.e., simethicone, magaldrate, magnesium carbonate, magnesium hydroxide, magnesium trisilicate, sodium bicarbonate and aluminium hydroxide was studied by using standard dissolution apparatus. Cephradine was monitored both by UV and by high performance liquid chromatography. The results revealed that antacids containing polyvalent cations retarded the in vitro availability of cephradine. Moreover, these studies indicated that cephradine was strongly adsorbed on antacids; magnesium trisilicate and simeco tablets (powdered) exhibited relatively higher adsorption capacities.

In vitro interaction studies of diltiazem with NSAID's using UV spectrophotometry and RP-HPLC techniques.

Diltiazem (DTZ) is a well-known cardiovascular drug used clinically in the treatment of angina pectoris and hypertension. Present paper deals with the in vitro availability studies of DTZ in presence of commonly used nonsteroidal anti-inflammatory drugs (NSAID's) like diclofenac sodium, flurbiprofen, mefenamic acid and meloxicam. Simultaneous administration of both types of drugs may alter the antihypertensive effect of DTZ. These studies were carried out using BP 2005 dissolution test apparatus in simulated human body environments at body temperature and at elevated temperature in order to study the kinetics and energitics of these interactions. Both the drug in each case were analyzed either by measuring the absorbance of aliquots on a UV/VIS spectrophotometer, or by RP-HPLC method. Present study clearly indicated that most of the NSAID's studied bind to DTZ forming charge transfer complexes, evident from the high availability of DTZ. Hence, concurrent administration of NSAID's with DTZ is not recommended.

Fabrication of solid nanoparticles for drug delivery.

The use of nanoparticles in biotechnology presents a growing interest for the numerous possibilities offered by combining the world of materials, with its advanced technologies and their diverse properties, and the biological world, with its elaborate molecular architectures, properties and functions. Different nanoparticles are attractive for their intrinsic properties of optical transparency, controllable porosity, chemical inertness and biocompatibility. Various synthetic methods have been developed for preparing nanoparticles with well-controlled sizes and shapes. Research in nanotechnology and biopharmaceutics or collectively nanomedicine has recently taken a new dimension, with amazing variety of methods for fabrication of nanoparticles. It is now possible to enhance or control drug delivery, this is required in case of poorly soluble drug, or drugs to cross blood brain barrier (BBB). Moreover, this technique can also be utilized for targeted delivery of drugs. There are number of methods reported in literature for the fabrication of nanoparticles. These include Sol-Gel technique, spraying the drug solution in vacuum, solvent diffusion or precipitation method. The former two techniques are mostly used to fabricate porous nanoparticles. Present paper reviews these techniques so as to give an idea to those planning to start with the fabrication of nanoparticles in a particular area of interest.

Optimization of levofloxacin analysis by RP-HPLC using multivariate calibration technique.

A rapid and sensitive reverse phase high performance liquid chromatographic (RP-HPLC) method for the analysis of levofloxacin from bulk materials, dosage formulations and human serum is described. This isocratic method employs, a Nucleosil, C18 (10 microm, 25 cm x 0.46 cm) column with a mobile phase of water and acetonitrile (6:5), where in phosphoric acid was used to adjust the pH to 2.9 and propylparaben as an internal standard. Optimization of levofloxacin analysis was carried out using multivariate calibration technique and detector response was recorded at five different wave lengths. A linear response (r > 0.9999) was observed in the range of 40 to 10000 ng ml(-1). The method shows good recoveries, intra and inter-day relative standard deviations were less than 1.2 %. Validation parameters as specificity, accuracy and robustness were also determined. The method can conveniently be used for analysis of levofloxacin pharmacokinetic levels in human serum and pharmaceutical formulations.

Multivariate calibrations in UV spectrophotometric analysis.

Calibration allows the user to relate instrumental measurements to the sample of interest. Multivariate calibration allows for the analysis of several measurements from several samples or specimens. The method contributes to the two steps procedure where step one involves the calibration of data and second step involves the prediction that are made or based on the calibration. In calibration, indirect measurements are made from samples where the amount of the analyte has been predetermined, usually by an independent assay or technique. These measurements, along with the predetermined analyte levels, comprise a group known as the calibration set. This set is used to develop a model that relates the amount of sample to the measurements by the instrument. In some cases, the construction of the model is simple due to a certain relationship, such as Beer's Law in the application of UV spectroscopy. Unlike spectroscopy, other cases can be much more complex, and it is in these cases where construction of the model is time-consuming step. Once the model is constructed, it can predict analyte levels based on measurements of new samples. It can be used to separate samples from interferences without the need of highly selective measurements for the analyte. Calibration techniques (used in the calibration step) differ in determining coefficient values for the preceding or similar equations.

Simultaneous determination of cefazolin or ceftizoxime in presence of ascorbic acid from pharmaceutical formulation and human serum by RP-HPLC.

A rapid, sensitive and specific RP-HPLC method involving HPLC-UV detection was developed and validated for simultaneous determination and quantification of cefazoline or ceftizoxime in presence of ascorbic acid. Chromatography was carried out on a pre-packed Kromasil 100, C(18) (5 microm 25 x 0.46 cm) column using acetonitrile: water (60:40; v/v) as mobile phase at a flow rate of 0.75 ml/minute and effluent were monitored at 265 nm for cefazoline and ascorbic acid while at 270 nm for ceftizoxime. The assay was linear over the concentration range of 0.05-100 microg/ml. The method is convenient for determination of cefazoline or ceftizoxime in presence of ascorbic acid with percent recovery ranging from 99.0-100.0% with an inter and intra day CV <3%. The method does not require more than 8 minutes for analysis with good peak resolution and low LOD 0.1 microg/ml and LOQ 0.3 microg/ml.

The berberis story: Berberis vulgaris in therapeutics.

Barberry has played a prominent role in herbal healing for more than 2,500 years. Berberis vulgaris is a common garden bush, native to Europe and the British Isles, naturalized in North America, seems to have history as old as human race. Anthropologists believe in a ritual practice or sacred object, especially by Native Americans that it works as a supernatural power or as preventive or remedy of illness. It is a deciduous shrub having yellow flowers and scarlet colored fruit in the form of berries. Twenty two alkaloids have been reported so far from root, stem leaves and fruit of this plant, which are of medicinal importance. As a herbal remedy it has no match in serving human race since ancient times. It is the most widely used drug in Homeopathic system of medicine for kidney pain and for removal of kidney stones. In this article, we present countless blessings of nature encountered through this herb which are worthy of recording.

In vitro availability studies of enoxacin in presence of H2 receptor antagonists.

Enoxacin is a second-generation quinolone with increased antibacterial activity both in potency as well as in terms of broad spectrum against a wide range of clinically important pathogens over the first generation quinolones and produces its effect by inhibiting bacterial enzyme DNA gyrase. There are a number of drug interactions reported for enoxacin. On the other hand H2-receptor antagonists block gastric acid secretion and some cardiovascular effects of histamine. As the later drugs are used for a long-term therapy, they may be coadministered with other drugs. In present study in vitro release of enoxacin in presence of cimetidine, ranitidine and famotidine has been studied on a B.P. 2003 dissolution test apparatus and compared with the availability of enoxacin and H2-receptor antagonists alone. The interacting drugs were analyzed spectrophotometrically. These studies were carried out in simulated gastric juice, simulating empty stomach, simulated intestinal juice (pH 9) and buffers of pH 7.4 simulating blood pH at 37 degrees C. In order to support these interaction studies, the effect of H2-receptor antagonists on the antibacterial efficacy (MIC) of enoxacin was also studied by turbidity method and compared with parent drug against Staphylococcus aureus, Streptococcus pyogens, Streptococcus pneumoniae, Enterococcus, Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis and Bacillus subtilis. On the basis of these results, it is suggested that enoxacin should be coadministered with care along with H2-receptor antagonists especially in case of ranitidine, although chances of adverse reactions are rare but decrease in MIC of enoxacin may result in delayed effect or require prolonged use of the drug.