Validated spectrophotometric determination of maduramicin ammonium using three charge transfer complexation reactions.

Direct spectrophotometric determination of Maduramicin ammonium (MAD) represents an analytical challenge since it is a weak UV-absorbing and lacking a strong chromophore. This work represents the first spectrophotometric determination of MAD as no direct spectrophotometric or colorimetric determination methods for MAD are available in the literature. The present study illustrates the development of three simple, rapid and inexpensive colorimetric methods for the routine quality control analysis of MAD based on the formation of colored charge transfer complexes with three electron acceptors namely p-chloranilic acid (p-CA), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and picric acid (PA). The color products of MAD with p-CA, DDQ and PA were measured at 519, 588 and 405nm respectively. The proposed methods were validated in terms of linearity, ranges, precision, accuracy, robustness and limits of detection and quantification. MAD was effectively determined over concentration ranges of 100-1000, 25-250 and 30-150µg/mL using p-CA, DDQ and PA, respectively with good linearity as shown by the values of correlation coefficients not less than 0.9991. The developed methods were successfully implemented in the assay of MAD powder pharmaceutical formulation for veterinary use.

Validated spectrophotometric and chromatographic methods for simultaneous determination of ketorolac tromethamine and phenylephrine hydrochloride.

This work describes five simple and reliable spectrophotometric and chromatographic methods for analysis of the binary mixture of ketorolac tromethamine (KTR) and phenylephrine hydrochloride (PHE). Method I is based on the use of conventional Amax and derivative spectrophotometry with the zero-crossing technique where KTR was determined using its Amax and (1)D amplitudes at 323 and 341nm respectively, while PHE was determined by measuring the (1)D amplitudes at 248.5nm. Method II involves the application of the ratio spectra derivative spectrophotometry. For KTR, 12µg/mL PHE was used as a divisor and the (1)DD amplitudes at 265nm were plotted against KTR concentrations; while - by using 4µg/mL KTR as divisor - the (1)DD amplitudes at 243.5nm were found proportional to PHE concentrations. Method III depends on ratio-difference measurement where the peak to trough amplitudes between 260 and 284nm were measured and correlated to KTR concentration. Similarly, the peak to trough amplitudes between 235 and 260nm in the PHE ratio spectra were recorded. For method IV, the two compounds were separated using Merck HPTLC sheets of silica gel 60 F254 and a mobile phase composed of chloroform/methanol/ammonia (70:30:2, by volume) followed by densitometric measurement of KTR and PHE spots at 320 and 278nm respectively. Method V depends on HPLC-DAD. Effective chromatographic separation was achieved using Zorbax eclipse plus C8 column (4.6×250mm, 5µm) with a mobile phase consisting of 0.05M o-phosphoric acid and acetonitrile (50:50, by volume) at a flow rate 1mL/min and detection at 313 and 274nm for KTR and PHE respectively. Analytical performance of the developed methods was statistically validated according to the ICH guidelines with respect to linearity, ranges, precision, accuracy, detection and quantification limits. The validated spectrophotometric and chromatographic methods were successfully applied to the simultaneous analysis of KTR and PHE in synthetic mixtures of different proportions and laboratory-made ophthalmic solution.

Utility of 2,3-dichloro-5,6-dicyano-p-benzoquinone in assay of codeine, emetine and pilocarpine.

A simple and sensitive spectrophotometric method for the assay of codeine, emetine and pilocarpine is described, based on the interaction of these drugs (as n-electron donors) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (as pi -acceptor) to give a highly coloured radical anion which exhibits maximum absorption at 460 nm. Formation of the radical anion has been established by electron spin resonance measurements. Beer's law is obeyed for the alkaloids investigated. The assay results are in accord with pharmacopoeial assay results. The procedure is sufficiently sensitive to permit unit dose assay of the individual alkaloids in pharmaceutical formulations.

Colorimetric determination of two fenamates in capsule dosage form.

The colorimetric determination of mefenamic acid and flufenamic acid with potassium ferricyanide in sodium hydroxide medium is described. The orange product is measured at 464 nm. The molar absorptivities are 1.9 x 10(3) and 2.9 x 10(3) 1.mole(-1).cm(-1) for mefenamic acid and flufenamic acid, respectively. The method has been applied successfully to the determination of these drugs in capsules.

Quantitation of indomethacin, naproxen, and ibuprofen in pharmaceutical dosage forms by first and second derivative ultraviolet spectrometry.

First and second derivative ultraviolet spectrometric methods are described for the estimation of indomethacin, naproxen, and ibuprofen in pharmaceutical dosage forms. The proposed methods permit the rapid, precise, and accurate determination of indomethacin capsules BP, naproxen capsules, and ibuprofen tablets BP. Matrix interference is successfully corrected. The results obtained by first and second derivative techniques are in accord with those obtained by the official assay method.

Spectrophotometric determination of phenothiazines, tetracyclines and chloramphenicol with sodium cobaltinitrite.

A spectrophotometric method for determining some phenothiazines, some tetracyclines and chloramphenicol is described. Chlorpromazine hydrochloride, promazine hydrochloride, promethazine hydrochloride, perphenazine and fluphenazine hydrochloride are reacted with sodium cobaltinitrite in phosphoric acid. The red colour developed is measured at 530, 513, 515, 530 and 500 nm, respectively. Tetracycline hydrochloride, oxytetracycline hydrochloride, chlortetracycline hydrochloride, doxycycline hyclate and demeclocycline hydrochloride are reacted with the reagent in aqueous acetic acid. The yellow colour produced is measured at 256, 294, 262, 243 and 246 nm, respectively. Chloramphenicol is determined similarly to the tetracyclines after hydrolysis with 40% sodium hydroxide solution and the colour is measured at 240 nm. The proposed method has been successfully applied to the determination of these drugs in various pharmaceutical preparations.

Spectrophotometric determination of tetracyclines and cephalosporins with ammonium vanadate.

A spectrophotometric method for the determination of some tetracyclines as well as some cephalosporins is described. The drug is boiled with ammonium vanadate solution in sulphuric acid medium for 10 min and the absorbance of the colour developed is measured at 750 nm. The proposed method can be successfully applied to the determination of tetracycline hydrochloride, oxytetracycline hydrochloride, doxycycline hyclate, demeclocycline hydrochloride, chlortetracycline hydrochloride, cephalothin sodium, cephaloridine and cephapirin sodium. These drugs can be determined either in pure form or in pharmaceutical preparations.

Investigation of some materials as dry binders for direct compression in tablet manufacture. Part 6: Effect of drug.

The effect of addition of ascorbic acid, which is a drug known to be difficult to compress directly, on the self-binding efficiency of tragacanth, Carbowax 4000, Plasdone, and mannitol were investigated. The flow properties of ascorbic acid of different particle sizes were determined since they would affect the flowability of the binders investigated and would help to determine the optimum particle size of the drug required for maximum binding efficiency.

Investigation of some materials as dry binders for direct compression in tablet manufacture. Part 7: Formulation and evaluation of ascorbic acid and phenobarbitone tablets.

Directly compressible powder blends containing either ascorbic acid or phenobarbitone, and utilizing tragacanth, Carbowax 4000, Plasdone, and mannitol as dry binders, were formulated. The flowability of the powder mixes prior to compression was determined. Furthermore, the tablets prepared according to the suggested formulae were tested for hardness, friability, uniformity of weight, distribution of active ingredient, disintegration, and dissolution. The effect of aging on the qualities of the tablets was also studied.

Investigation of some materials as dry binders for direct compression in tablet manufacture. Part 5: Effects of lubricants and flow conditions.

The effect of talc, magnesium stearate, stearic acid, and Acrawax C, which are commonly used as lubricants, on the dry-binding efficiency of tragacanth, polyethylene glycol 4000, polyvinylpyrrolidone, and mannitol were investigated. The effect of Aerosil which is sometimes utilized as a flow conditioner for directly compressible powder blends was also studied. The type and concentration of lubricant or flow conditioner appeared to influence the binding efficiency of the binders investigated to various degrees. The results showed that the bonding characteristics of all the binders tested except mannitol were reduced by the addition of the lubricants and the flow conditioner.

Investigation of some materials as dry binders for direct compression in tablet manufacture. Part 3: Effect of diluents.

The effects of lactose and dibasic calcium phosphate as diluents on the dry-binding qualities of tragacanth, polyethylene glycol 4000, polyvinylpyrrolidone and mannitol were investigated. The type, concentration and particle size of the diluent appeared to influence the flowability and the binding properties of the binders investigated.

Investigation of some materials as dry binders for direct compression in tablet manufacture. Part 4: Effect of disintegrants.

The effects of starch and Veegum as disintegrants on the dry-binding qualities of tragacanth, polyethylene glycol 4000, polyvinylpyrrolidone and mannitol were investigated. The type of diluent and its concentration in the powder blends appeared to influence the binding efficiency of the binders investigated.

Investigation of some materials as dry binders for direct compression in tablet manufacture. Part 2: Comparative self-binding properties.

Comparative self-binding qualities of four substances studied as potential dry binders for direct compression applications in tablet making were investigated. The effect of particle size of these materials on hardness, friability and hardness-friability ratio of disks made with mere binders was studied. The results showed that for comparable particle sizes, values of hardness-friability ratio of the various disks were in the following descending order: Plasdone, tragacanth, Carbowax 4000 and then mannitol.

Investigation of some materials as dry binders for direct compression in tablet manufacture. Part 1: flow properties and water sorption.

Four substances were evaluated for their potential usefulness as dry binders for direct compression techniques in tablet making. The flow properties of these substances including angle of repose, timed delivery through an orifice and compressibility were determined. The effect of particle size of the binder on its flow properties was investigated. Comparative rates of water sorption demonstrated by the various substances evaluated as dry binders were also determined.