ABSTRACT
A rapid, simple, and accurate first-derivative spectrophotometric method has been established for the determination of either cephalexin or cephradine in urine. Quantitative analysis of each antibiotic was achieved by measuring the peak amplitude at 268 nm. The relative and absolute recoveries ranged from 98.90 to 104.00% for cephalexin and from 97.85 to 105.10% for cephradine. The within-day coefficient of variation varied from 3.27 to 6.45%. The applicability of the method for the determination of the cumulative amount of either cephalexin or cephradine excreted unchanged in urine, following an oral dose containing 500 mg of the drug to a human male volunteer, is demonstrated.
Subject(s)
Cephalexin/urine , Cephradine/urine , Adult , Humans , Male , SpectrophotometryABSTRACT
Two methods for determination of phenylbutazone and oxyphenbutazone are described. In the first, naphthoquinone reacts with the product of acid hydrolysis of phenylbutazone or oxyphenbutazone to give an orange colour, having maximum absorption at 480 and 465 nm respectively. In the second, lead tetra-acetate reacts with the hydrolysis product of phenylbutazone (benzidine) to develop a green colour which on heating or addition of excess of reagent changes to yellow, with maximum absorption at 340 nm. Oxyphenbutazone gives a yellow colour with the reagent in the cold, with maximum absorption at 359 nm.
ABSTRACT
Heating paracetamol in strongly alkaline medium with 4-nitrosoantipyrine gives a red colour with maximum absorption at 515 nm. Mefenamic and flufenamic acids can be determined colorimetrically after extraction as ion-pairs with Methylene Blue.
ABSTRACT
The degradation of 6-selenoguanosine (NSC 137679) (I) in water and in various buffer systems was investigated. Drug degradation in aqueous media was monitored by high-pressure of I in various chromatography. Some kinetic aspects of the degradation of I in various buffer systems at 25 degrees also were studied spectrophotometrically. The degradation, which requires oxygen, involves autoxidation of I to the corresponding diselenide, which produces a selenide and metallic selenium in the presence of oxygen. This degradation pathway differs from that reported fro the oxidation of related thio compounds.
Subject(s)
Guanosine/analogs & derivatives , Organoselenium Compounds , Selenium , Chemistry, Pharmaceutical , Chromatography, High Pressure Liquid/methods , Drug Stability , Kinetics , Oxidation-Reduction , SolutionsABSTRACT
6-Selenoguanosine (NSC 137679) was stablized and formulated as a lyophilized parenteral paroduct using ascorbic acid as an antioxidant. In addition to preventing the oxidation of 6-selenoguanosine to the corresponding diselenide in aqueous solution, ascorbic acid reduced the diselenide already in the bulk drug. Dithioerythritol and sodium bisulfite also were evaluated as antioxidants. Dithioerythritol had effects similar to ascorbic acid, while sodium bisulfite reacted rapidly with 6-selenoguanosine.
Subject(s)
Antineoplastic Agents/chemical synthesis , Antioxidants , Guanosine/analogs & derivatives , Organoselenium Compounds , Selenium/chemical synthesis , Antineoplastic Agents/isolation & purification , Ascorbic Acid , Chemical Phenomena , Chemistry , Chromatography, High Pressure Liquid , Dithioerythritol , Drug Stability , Guanosine/chemical synthesis , Guanosine/isolation & purification , Oxidation-Reduction , Selenium/isolation & purificationABSTRACT
In the synthetic approach to some new local anaesthetics, it was desirable to prepare esters of N1-methyl-N4-hydroxypiperazine and N.N-dibenzylhydroxylamine. Their local anaesthetic activity testing is in progress.
Subject(s)
Anesthetics, Local/chemical synthesis , Hydroxylamines/chemical synthesis , Piperazines/chemical synthesis , Chemical Phenomena , Chemistry , Hydroxylamines/pharmacology , Piperazines/pharmacologyABSTRACT
This paper describes a spectrophotometric method for the assay of phenothiazines (and also opipramol, which is similar but contains a CC linkage instead of the S atom of the phenothiazines) as the pure drug or in tablets or solutions for injection. The colour is produced by heating a solution of the drug or drug preparation with a solution of chloramine-T. The coloured product can be extracted into chloroform before the colour measurement or the whole process carried out in ethanol solution, the colour of which is then measured.
ABSTRACT
A titrimetric method for the evaluation of some tranquillizers and antidepressants is proposed. The method is based on the oxidation of these drugs by iodine monochloride, in strong acid medium, the iodine liberated being titrated with potassium iodate by the Andrews method. The proposed method is applied successfully for the determination of 9 phenothiazines, 1 thioxanthene, 2 acid hydrazides and 1 dibenzazepine containing a double bond (Opipramol). Tablets, solutions for injection, and drops are also determined by the proposed method. The mechanism of oxidation for each species is suggested and the results obtained agree with these suggestions. Some official and non-official methods for the evaluation of the drugs have been compared with the iodine monochloride method, which is found to be superior in specificity, sensitivity and speed.
ABSTRACT
A spectrophotometric method for determining some penicillins has been developed. A known volume of the penicillin solution-in phosphate buffer of pH 6.8 is boiled with ammonium vanadate solution-in sulphuric acid medium-for 10 min and the absorbance of the colour formed is measured at 750 nm. The excess of vanadate can also be determined volumetrically. The method has been successfully applied for the determination of penicillin G sodium, phenoxymethyl penicillin, ampicillin sodium, phenethicillin potassium, cloxacillin sodium and methicillin sodium. The procedure is also used for analysing some pharmaceutical preparations of these drugs, e.g., injections. The results obtained are in agreement with those of the B P 1973 methods.
