Spectrophotometric determination of ampicillin and its dosage forms.

A new spectrophotometric procedure is described for the determination of ampicillin. The method is based on the reaction of ampicillin with acetylacetone-formaldehyde reagent to give a yellow coloured product having lambda max at 400 nm. A variety of pharmaceutical dosage forms containing ampicillin are successfully analysed by the proposed procedure.

Synthesis and pharmacological study of antihyperlipaemic activity of 2-substituted thieno(2,3-d)pyrimidin-4(3H)-ones.

A series of 2-substituted thieno(2,3-d)pyrimidin-4-(3H) ones (1-15) was prepared by the reaction of thiophene ortho-aminoester (IV) with a variety of nitriles (V) under acidic conditions, and screened for antihyperlipaemic activity in various animal models. While most of these compounds were found active, 2-chloromethyl-5,6,7,8-tetrahydrobenzo(b)thieno(2,3-d) pyrimidin-4(3H)-one (5) was found to be the most active of all. The serum triglyceride lowering activity exhibited by 5 was found comparable to that of clofibrate and riboflavin tetrabutyrate. Compound 5 was also found to be safe as indicated by acute and chronic toxicity studies in mice and rats.

Kinetic studies of the interaction between isoniazid and reducing sugars.

The interaction between isoniazid and reducing sugars is acid-catalyzed and reversible. Kinetic studies of hydrazone formation from isoniazid and glucose, lactose, maltose, and galactose have been carried out in simulated gastric juice at 37 degrees C. The forward reaction was found to follow second-order kinetics, while the reverse reaction, the hydrolysis of the sugar isonicotinoyl hydrazone, is pseudo-first-order. The effects of the concentration of reactants, pH, and temperature on the rate have been studied, and the rate constants and the energy of activation were determined.

Spectrophotometric determination of chloramphenicol and its esters in complex drug mixtures.

When aromatic nitro compounds are reduced with zinc and calcium chloride and reacted with trisodium pentacyanoaminoferrate they give a purple product having an absorbance maximum between 480 and 540 nm. Applying this reaction, a quantitative method has been developed for the determination of chloramphenicol and its esters. Various reaction conditions have been standardized. Beer's law is obeyed in the concentration range of 4 to 32 micrograms/mL reaction mixture. Average recoveries and standard deviations were 99.78 +/- 0.627 and 99.90 +/- 0.660; 101.06 +/- 0.702; and 99.90 +/- 0.880% for chloramphenicol, chloramphenicol sodium succinate, and chloramphenicol palmitate, respectively. The method has also been applied to determine chloramphenicol and its esters as well as chloramphenical in the presence of combination drugs in dosage forms. The presence of benzocaine, lignocaine, sulfadiazine, nitrofurantoin, ascorbic acid, hydrocortisone, prednisolone, streptomycin, and tetracycline does not interfere with the proposed spectrophotometric procedure. The method does not require prior separation of chloramphenicol from combination drugs.

Spectrophotometric determination of isoniazid in presence of its hydrazones.

A spectrophotometric determination of isoniazid in the presence of its hydrazones was developed. The method involves the reaction between isoniazid and 2,3-dichloro-1,4-naphthoquinone in the presence of ammonia in an ethanolic medium. The colored product has an absorbance maxium at 640 nm. The Lambert-Beer law is obeyed in the 1--14-microgram/ml range. The proposed method was applied to the analysis of isoniazid tablets. In commercial tablets, hydrazone formation due to the reaction between isoniazid and lactose was detected by TLC. The analysis of lactose-containing isoniazid tablets showed 10--22% lower recovery than that obtained by the official method. Hydrazone formation in tablets probably interferes with isoniazid bioavailability.

Synthesis and pharmacological properties of some 4-amino-5-substituted thiazole-2(3H)-thiones and thiazolo(4,5-d)pyrimidin-7(6H)-one-2(3H)-thiones.

4-Amino-5-substituted thiazole-2(3H)-thiones and thiazolo(4,5-d)-pyrimidin-7(6H)-one-2(3H)-thiones have been synthesized and screened for antimicrobial and pharmacological activities. Significant analgesic, antiinflammatory, anticonvulsant and antimicrobial properties have been found in some of the compounds synthesized. Analgesic and antiinflammatory activities are reported for the first time in thiazole-2(3H)-thiones.

Synthesis of 3-substituted thieno [2, 3-d] pyrimidin-4(3H)-one-2-mercaptoacetic acids and their ethyl esters for pharmacological screening.

3-Substituted thieno [2, 3-d] pyrimidin-4(3H)-one-2-mercaptoacetic acids and their ethyl esters were synthesized from 2-mercaptothieno [2, 3-d] pyrimidin-4(3H]-ones, which were obtained by cyclization of thienylthioureas in acidic medium. Analgesic, anti-inflammatory, and anticonvulsant activities were found in some of these compounds. Significant antimicrobial activity was exhibited by thienylthioureas.

Spectrophotometric determination of allylisothiocyanate in mustard seed oil.

Allylisothiocyanate is determined spectrophotometrically after reaction with 2,3-dichloro-1,4-naphthoquinone. For pure samples, the color intensity is proportional to allylisothiocyanate content in the range 0.8-3.0 mg/ml reaction mixture. A modified procedure is used to estimate allylisothiocyanate content of mustard seed oil. The reaction is linear for allylisothiocyanate concentrations in the range 40-240 mug/ml reaction mixture. Two mustard seed oil samples contained 0.995 not equal to 0.020 and 0.981 not equal to 0.019% allylisothiocyanate.