Atomic emission spectrometric determination of ephedrine, cinchonine, chlorpheniramine, atropine and diphenhydramine based on formation of ion associates with ammonium reineckate

Spectroscopic study of structure of diphenhydramine drug and its products obtained via reactions with tetracynoethylene and iodine reagents and applications

The reactions between diphrenhydramine drug (diphen) in the base form and the iodine amphoteric reagent (n-donor and/or σ-acceptor) and tetracyanoethylene as a π-acceptor reagent (TCNE) have been spectrophotometrically studied at different conditions of reactant concentrations, time intervals, temperatures, solvents, and different wavelengths aiming to shed light on the nature of these reactions. Consequently, it is possible to select the proper conditions for spectrophotometric determination of this biologically active drug in its formulations. The reaction mechanism between iodine and diphen involves the formation of diphen-I₂ outer-and inner-sphere complexes, whereas diphen-TCNE reaction involves the formation of charge transfer (CT) complex. The analytical parameters of the suggested spectrphometric procedures have been calculated. The values of the Sandell sensitivity, standard deviation (SD), relative standard deviation (RSD) and recovery % refer to the high sensitivity of these procedures applied in analysis of diphen in its formulations. This research also presents a new diphen-I₂ promising drug derivative that can be used for the same purpose as its parent. Both diphen-drug and diphen-I₂ separated solid product are critically investigated by elemental analyses, FT-IR, ¹HNMR, electron ionization mass spectrometry (EI-MS) and thermal analyses (TA). Practical investigation (TA and MS) data of diphen-drug and its reaction product are confirmed by MO calculations. This research gives a clear idea about the possible metabolites and metabolic pathways of diphen and its derivative in vitro system that may occur in vivo system. The importance of this drug stems from its use as an antihistamine with anticholinergic (drying) and sedative side effects.

Spectrophotometric determination of some histamine H1-antagonists drugs in their pharmaceutical preparations

Two rapid, simple and sensitive extractive specrophotometric methods has been developed for the determination of three histamine H1-antagonists drugs, e.g., chlorphenoxamine hydrochloride (CPX), diphenhydramine hydrochloride (DPH) and clemastine (CMT) in bulk and in their pharmaceutical formulations. The first method depend upon the reaction of molybdenum(V) thiocyanate ions (Method A) with the cited drugs to form stable ion-pair complexes which extractable with methylene chloride, the orange red color complex was determined colorimetrically at lambda(max) 470nm. The second method is based on the formation of an ion-association complex with alizarin red S as chromogenic reagents in acidic medium (Method B), which is extracted into chloroform. The complexes have a maximum absorbance at 425 and 426nm for (DPH or CMT) and CPX, respectively. Regression analysis of Beer-Lambert plots showed a good correlation in the concentration ranges of 5.0-40 and 5-70microgmL(-1) for molybdenum(V) thiocyanate (Method A) and alizarin red S (Method B), respectively. For more accurate analysis, Ringbom optimum concentration ranges were calculated. The molar absorptivity, Sandell sensitivity, detection and quantification limits were calculated. Applications of the procedure to the analysis of various pharmaceutical preparations gave reproducible and accurate results. Further, the validity of the procedure was confirmed by applying the standard addition technique and the results obtained in good agreement well with those obtained by the official method.

A new hydrophilic interaction liquid chromatographic (HILIC) procedure for the simultaneous determination of pseudoephedrine hydrochloride (PSH), diphenhydramine hydrochloride (DPH) and dextromethorphan hydrobromide (DXH) in cough-cold formulations

A new HILIC method has been developed for the simultaneous determination of pseudoephedrine hydrochloride (PSH), diphenhydramine hydrochloride (DPH) and dextromethorphan hydrobromide (DXH) in cough-cold syrup. Mobile phase consists of methanol:water (containing 6.0 g of ammonium acetate and 10 mL of triethylamine per liter, pH adjusted to 5.2 with orthophosphoric acid), 95:5 (v/v). Column containing porous silica particles (Supelcosil LC-Si, 25 cm x 4.6 mm, 5 microm) is used as stationary phase. Detection is carried out using a variable wavelength UV-vis detector at 254 nm for PSH and DPH, and at 280 nm for DXH. Solutions are injected into the chromatograph under isocratic condition at constant flow rate of 1.2 mL/min. Linearity range and percent recoveries for PSH, DPH and DXH were 150-600, 62.5-250, 75-300 microg/mL and 100.7%, 100.1% and 100.8%, respectively. Method is stability indicating and excipients like saccharin sodium, sodium citrate, flavour and sodium benzoate did not interfere in the analysis. Compounds elute in order of increasing ionization degree caused by cation-exchange mechanism in a run time of less than 15 min. Mobile phase pH is manipulated to regulate ionization and ion-exchange interaction and thereby retention of compounds.

Determination of verapamil in pharmaceutical formulations using atomic emission spectrometry

Ion-associate complexes of verapamil hydrochloride (VpCl) with (Cd(II), Co(II), Mn(II), and Zn(II)) thiocyanates, potassium ferricyanide, and ammonium reineckate are precipitated. The solubility of the solid complexes at the recommended optimum conditions of pH and ionic strength values have been studied. Saturated solutions of each ion associate at different temperatures under the optimum precipitation conditions were prepared and the metal ion contents in the supernatant were determined. The solubility products were thus calculated at different temperatures and the thermodynamic parameters DeltaH, DeltaG, and DeltaS were calculated. A new accurate and precise method based on direct coupled plasma atomic emission spectrometry for the determination of VpCl (1.96-62.86 microg ml(-1)) in pure solutions and pharmaceutical preparations is given.