LC-MS/MS Validation Analysis of Trastuzumab Using dSIL Approach for Evaluating Pharmacokinetics.

Quantitative targeted proteomics based approaches deploy state-of-the-art Liquid chromatography tandem mass spectrometry LC-MS technologies and are evolving as a complementary technique to standard ligand-binding based assays. Advancements in MS technology, which have augmented the specificity, selectivity and sensitivity limits of detection and freedom from antibody generation, have made it amicable towards various clinical applications. In our current work, a surrogate peptide based quantitative proteomics assessment is performed by selecting specific signature peptides from the complementary determining region CDR region of trastuzumab (Herclon®, Roche products in India). We developed a double Stable Isotope Label (dSIL) approach by using two different surrogate peptides to evaluate the proteolytic digestion efficiency and accurate quantification of the target analyte peptide of Herclon® in human serum. Method validation experiments were meticulously performed as per bioanalytical method validation guidelines. The dSIL approach, using an LC-MS/MS based quantification assay demonstrated good linearity over a range of 5-500 µg/mL of Herclon®, and validation experimental data is in compliance with bioanalytical regulatory guidelines.

Chirality--a new era of therapeutics.

To develop the newer pharmaceuticals and to spur the strong growth, being a general property of 'handedness', chirality plays a major role. The Easson-Stedman principle shows the differences in the biological activity between enantiomers resulted from selective reactivity of one enantiomer with its receptor. It helps to improve the pharmacokinetic properties and to remove undesirable side effects by virtue of the unique activity of enantiomers. Racemic switching and marketing drug combinations are used as tools for drug life-cycle management and to redevelop racemic mixtures as single enantiomers.

Dynamic instability at liquid/vapor interface far from equilibrium.

Attempt has been made to elucidate the mechanism of electric potential oscillations at oil-aqueous solution interface involving adsorption at oil-vapor interface on a semi-theoretical basis. The mechanism stipulates adsorption of ammonia, amines and pheromones at the liquid-vapor interface followed by transfer of ions through membrane-aqueous solution interface and subsequent interaction of ammonium (amine) ions and carbocations from pheromones with diffusing halide ions from the bulk. Relationship of the above mechanism with sensing mechanism of smell by olfactory nerves has also been pointed out.

Cyclodextrin based ternary system of modafinil: Effect of trimethyl chitosan and polyvinylpyrrolidone as complexing agents.

Modafinil is an approved drug for the treatment of narcolepsy and have a strong market presence in many countries. The drug is widely consumed for off-label uses and currently listed as a restricted drug. Modafinil has very low water solubility. To enhance the aqueous solubility of modafinil by the formation of a ternary complex with Hydroxypropyl-ß-cyclodextrin and two hydrophilic polymers was the main objective of the present study. Pyrrolidone (PVP K30) and a water soluble chitosan derivative, trimethyl chitosan (TMC) were studied by solution state and solid state characterization methods for their discriminatory efficiency in solubility enhancement of modafinil. Phase solubility study depicted the highest complexation efficiency (2.22) of cyclodextrin derivative in the presence of TMC compared to the same in the presence of PVP K30 (0.08) and in the absence of any polymer (0.92). FT-IR analysis of binary and ternary complex expressed comparable contribution of both polymers in formation of inclusion complex. The thermal behaviour of binary and ternary complex, involving individual polymers disclosed the influence of TMC on polymorphism of the drug. DSC study revealed efficiency of TMC to prevent conversion of metastable polymorphic form to stable polymorphic form. Ternary complex, involving TMC enhanced water solubility of the drug 1.5 times more compared to the binary complex of the drug whereas PVP K30 reduced the Solubility.

Chiral chromatographic separation of beta-blockers.

A novel amide based chiral stationary phase m-[(+)-alpha-methyl benzyl carboxamide] XAD-4 has been synthesized by covalently linking R(+)-1-phenylethylamine to chloroformoyl Amberlite XAD-4 under weak alkaline conditions. The synthesized resin has been primarily characterized by m.p., elemental analysis and FT-IR and 13C NMR spectra. beta-Blockers viz. atenolol, metoprolol, and propranolol were successfully separated into their enantiomers using a mixture of sodium acetate-acetic acid buffer (pH 4.1):acetonitrile (4:6, v/v) solution using the synthesized resin. Hydrogen bonding and pi-pi interactions are supposed to be the major analyte-chiral stationary phase interactions.

Chitosan as a suitable nanocarrier material for anti-Alzheimer drug delivery.

Chitosan, a biocompatible natural polysaccharide is frequently reported carrier material in targeted drug delivery to treat neurodegenerative disorders. Chitosan and its biodegradable products exert its bioactivities on nerve cells and blood brain barrier at the molecular level, which are beneficial in anti-Alzheimer therapy. Flexibility of surface modification, the ability to get attached with varieties of ligand molecules and the formation of the stable nano complex in physiological condition make chitosan an adorable material for delivery of anti-Alzheimer drugs and siRNA to the brain. The success rate of nose to brain delivery of anti-Alzheimer drugs enhances when chitosan used as a carrier material. This review covers direct and indirect anti-Alzheimer effects of chitosan, surface modification strategies to augment permeation from the blood-brain barrier structure, different ligands reported for brain targeting of chitosan nanoparticles containing anti Alzheimer drugs, blood compatibility and widely utilized chitosan nanoparticle fabrication techniques. Key intellectual claims are also condensed through patents to appraise chitosan as an attractive polymer for brain targeted nanoformulation which is currently facing oversight by regulatory agencies and manufacturers.

Separation and trace estimation of benzidine and its macromolecular adducts using supercritical fluid chromatography.

A sensitive, rapid, selective and reproducible method has been developed to measure blood plasma levels of benzidine (BZ) and its acetylated metabolite, N-OH-N,N'-diacetylbenzidine (N-OH-DABZ), using supercritical fluid chromatography (SFC) for the first time. Benzidine and N-OH-N,N'-diacetylbenzidine were extracted from the plasma using ether. Separation was done on a Nucleosil (250 mm x 4.6 mm) 10 microm, Nucleosil-RP-C18 column with 7.4% (v/v) methanol-modified supercritical fluid carbon dioxide (2.5 ml min(-1)) as mobile phase. The column temperature was 45 degrees C and the outlet pressure was set at 8.83 MPa. The detection was done using a UV-Vis detector set at 280 nm. The limit of quantification was 0.10 ng ml(-1) (BZ) and 0.14 ng ml(-1) (N-OH-diacetylbenzidine) using 1 ml plasma specimen. The mean extraction recovery of BZ was found to be 98.6%. The SFC method was directly compared to a published HPLC-UV method. With respect to speed, organic solvent usage, sensitivity, specificity and accuracy, SFC was found to be superior. The method has been successfully used to estimate the BZ, N-OH-diacetylbenzidine levels in blood plasma of the animals who were administered 15 microg kg(-1) body weight of benzidine.Further, this method has been also applied for the detection and quantification of benzidine DNA and hemoglobin adducts from the blood and tissue samples of the benzidine dosed animals.

Effect of binders on sulfamethoxazole tablets.

Five batches of sulfamethoxazole tablets were prepared using different binders [starch, acacia, ethyl cellulose sodium carboxymethylcellulose, and povidone (1-vinyl-2-pyrolidinone polymer, PVP)] with water in 3% (dry basis) concentration. Comparative data show that granules prepared with PVP have the best flow properties and minimum angle of repose, percentage fines, and compressibility, while granules of sodium carboxymethylcellulose could not be compressed into well-defined tablets. Tablets containing starch as a binder possess all the quality features. Tablets from acacia, however, give a poor dissolution profile. Ethyl cellulose has less effective granule formation, leading to poor quality tablets. Rank correlation with respect to solubility and absorption characteristics according to granulating agent in the formation is: starch greater than ethyl cellulose greater than PVP greater than acacia.

Thermodynamic proton-ligand and metal-ligand stability constants of some drugs.

The thermodynamic proton-ligand (pKa) and metal-ligand stability constants of clioquinol, clofibrate, nitrofurazone, and tetracycline with Cu2+, Zn2+, Mn2+, Mg2+, and Ca2+ have been determined at 35 degrees C in 50% ethanol-water media. An empirical pH correction for mixed-aqueous media has been applied. The metal-ligand stability constants were determined by following the Bjerrum Calvin titration technique as applied by Agrawal to mixed-aqueous solvents. The effect of the basicity of the ligand and the order of stability constants is discussed. The stability constants of the divalent metals follow the order: Cu2+ greater than Zn2+ greater than Mn2+ greater than Mg2+ greater than Ca2+ with all the drugs.

Sulfa drugs: thermodynamic proton-ligand and metal-ligand stability constants.

The thermodynamic proton-ligand stability constants of sulfa drugs have been determined in different mole fractions of dioxane (0.083-0.174) at 25 and 35 +/- 0.1 degrees C. Empirical corrections to pH meter readings in mixed aqueous media have been applied. The pKa varies linearly with the mole fraction of dioxane. Numerical equations expressing this linear relationship have been obtained using the method of least squares, and relevant correlation coefficients have been calculated. The thermodynamic parameters delta G degrees, delta H degrees, and delta S degrees are calculated. The effect of solvent and the change in free energy from mixed aqueous media, delta, is discussed. The thermodynamic metal-ligand stability constants of Cu(II), Pd(II), and Ce(IV) with sulfa drugs in 50% aqueous dioxane at 35 +/- 0.1 degrees C have been determined. The effect of basicity of the ligand and the order of the stability constant is discussed.

Gravimetric determination of cadmium with N-phenylbenzohydroxamic acid.

A quantitative gravimetric determination of cadmium in presence of Ag(+), Be(2+), Pb(2+), Mn(2+), Ni(2+), Cu(2+), Zn(2+), Hg(2+), Pd(2+), Ga(3+), Al(3+), Bi(3+), Sb(3+), La(3+), Ti(4+), Zr(4+), V(5+), Mo(6+) and U(6+) was made by selective precipitation with N-phenylbenzohydroxamic acid from a solution containing 6-15 mg of cadmium acetate at pH 5.8-6.5. The precipitate was weighed directly after drying at 110-120 degrees . The cadmium complex is curdy white, granular and melts at 225 degrees. The analytical results indicate the complex to be (C(13)H(10)NO(2))(2)Cd.

Correction factors for the glass electrode in aqueous dioxan.

The conversion factors for obtaining the hydrogen ion concentration from pH measurements at different mole fractions of dioxan in water at 25, 30 and 35 degrees are reported.

Spectrophotometric determination of clofibrate.

A sensitive method for the rapid and accurate determination of clofibrate by hydroxamic acid formation is described. Hydroxylamine hydrochloride is reacted with clofibrate in alkaline medium to give 4-chlorophenoxyisobutyrohydroxamic acid, which forms a purple complex with iron(III) in acidic medium. Common excipients do not interfere.

Stability constants of some bivalent metal complexes of N-phenyl-o-tolylbenzohydroxamic acid.

The stability constants of the Cu(2+), Zn(2+), Ni(2+) and Mu(2+) complexes of N-phenyl-o-methoxybenzohydroxamic acid at 30 degrees in 50% v/v aqueous dioxan are: log K(1) 10.45, 8.16, 7.52, 6.33; log K(2) 8.90, 6.70, 6.01, 5.59 (for the ions in the order given).

Solvent extraction, spectrophotometric and inductively coupled plasma atomic emission spectroscopic (ICP-AES) determination of lanthanum(III) with crown hydroxamic acid.

A new crown hydroxamic acid, 5,14-N,N'-hydroxyphenyl-4,15-dioxo-1,5,14,18-tetraaza hexacosane (NHDTAHA) for the extraction and spectrophotometric determination of lanthanum(III) is described. Lanthanum(III) forms a yellow coloured complex with NHDTAHA, which is extracted with chloroform, having molar absorptivity 7.7 x 10(3) 1 mol(-1) per cm at 372 nm. The system obeys Beer's law in the range 1.2-20 ppm of lanthanum. The extract is directly aspirated for ICP-AES measurements, the limits for estimation are 5-140 ppb of lanthanum. Lanthanum has been determined in monazite sand and standard samples.

Separation and gravimetric determination of rare earths with N-m-Tolyl-m-nitrobenzohydroxamic acid.

N-m-Tolyl-m-nitrobenzohydroxamic acid is used as a reagent for separation and gravimetric determination of Ce(3+), La(3+), Pr(3+), Nd(3+), Sm(3+) and Gd(3+). By proper control of pH and use of masking agents these metal ions can be separated from several others and determined gravimetrically. The complexes can be weighed as (C(14)H(11)N(2)O(4))(3)M after drying.

Thermodynamic dissociation constants of N-phenylbenzohydroxamic acids and benzohydroxamic acid.

Thermodynamic association constants of benzohydroxamic acid and several ortho-substituted N-phenylbenzohydroxamic acids have been determined by pH titration in aqueous dioxan media at 25 degrees and 35 degrees . Empirical pH corrections for mixed aqueous media have been applied. The pK(a) values do not vary linearly with the reciprocal of dielectric constant of the medium, but a plot of pK(a) vs. the mole fraction of dioxan is linear at a given temperature. Values of DeltaG degrees , DeltaH degrees and DeltaS degrees are tabulated.

Preparation, properties and analytical application of thorium n-phenyl-o-nitrobenzohydroxamate.

A new complex of thorium(IV) with N-phenyl-o-nitrobenzohydroxamic acid (PNHA) has been prepared by reacting an aqueous solution of thorium with an alcoholic solution of PNHA at 60 degrees C and adjusting the pH to 4-4.5. The infrared spectra and thermal analysis of the complex are discussed. The use of PNHA for gravimetric determination of thorium is described.

Ion-exchange separation and spectrophotometric determination of vanadium in environmental samples.

A selective and sensitive method for the extraction and spectrophotometric determination of vanadium(V) in microgram quantities is described. The molar absorptivity of the yellow vanadium(V)-caffeic acid-Aliquat 336 extract is 1.3 x 10(4) 1.mole(-1).cm(-1) at 370nm. The method is compared with the atomic-absorption spectrometric method and applied to the trace determination of vanadium in steel, alloys, a rock and environmental samples.

Sequential liquid-liquid extraction graphite furnace atomic absorption spectrometric (GFAAS) and spectrophotometric determination of zirconium(IV) with calixarene hydroxamic acid.

A new calixarene hydroxamic acid, 25,26,27,28-tetrahydroxy-5,11,17,23-tetrakis (N-p-chlorophenyl) calix[4]arene hydroxamic acid (CPCHA) is synthesized and used for the extraction and graphite furnace atomic absorption determination of zirconium(IV). The extract is also determined spectrophotometrically as CPCHA-SCN complex having maximum absorbance at 447 nm with molar absorptivity 9.4x10(3) l mol(-1) cm(-1). The Beer's law obeys in the range of 1.0-9.5 ppm of zirconium. The graphite atomic absorption (GFAAS) increases the sensitivity by about 50 folds. The method is applied to the trace determination of zirconium(IV) in standard samples.