Use of high-pressure liquid chromatography for quantitative structure-activity relationship studies of sulfonamides and barbiturates

Chromatography in studies of quantitative structure-activity relationships

The rational bases, experimental techniques and conditions required for the chromatographic determination of the structural data of importance for studies on quantitative relationships between chemical structure and biological activity of drugs (QSAR) are reviewed. Practical applications of the information gathered from various chromatographic modes in correlation with bioactivity data are discussed.

High-pressure liquid chromatographic identification of drugs used in management of arthritis

A screening procedure was developed for the identification of drugs used in the clinical treatment of arthritis. Each glucocorticoid, nonsteroidal anti-inflammatory agent, or tranquilizer was characterized by its retention on a reversed-phase high-pressure liquid chromatographic column and by the ratio of the response of dual UV detectors (254 and 280 nm). Although the retention times of all 14 drugs examined were less than 4 min. each drug could be distinguished easily from the other drugs in the series.

Identification and quantitation of nucleosides, bases and other UV-absorbing compounds in serum, using reversed-phase high-performance liquid chromatography. I. Chromatographic methodology

A comprehensive investigation of the high-performance liquid chromatographic separation of nucleosides, their bases and other low-molecular-weight UV-absorbing compounds that might be found in serum is reported. A buffer-methanol gradient was used in conjunction with chemically bonded, microparticulate columns to separate many of the biologically important compounds under study in minimal time with maximal resolution. Retention data, absorbance ratios (280/254 nm) and fluorescence responses are reported for 86 nucleosides, bases, nucleotides and other UV-absorbing compounds commonly encountered in biological studies.

Stability-indicating sulfa drug analysis using high-performance liquid chromatography

Sensitive and efficient methods for sulfonamide determination as single entities and in combination with other drug substances in pharmaceutical dosage formulations were developed using high-performance liquid chromatography. These stability-indicating procedures involved a nitrile bonded phase column and nonaqueous mobile phases having diverse polarities. Sample potency was determined using peak height measurements. The methods may be used to determine trace sulfonamide quantities because detection limits are in the nanogram range.

Facile separation of sulfonamides from their degradates by liquid--liquid extraction

Regulation of acidity for protonation of the free N4-amine can provide for the selective liquid--liquid extraction isolation of a sulfonamide from its degradation products. This principle is applied for the stability-indicating determination of sulfacetamide in the presence of sulfanilamide, sulfaquinoxaline in feed, and sulfabromomethazine in dosage forms. In solution, sulfabromomethazine can exhibit photodecomposition to sulfamethazine. The mean relative errors of the these methods and the precision, represented by relative standard deviations, are each typically less than 2%.

Simple procedure for determining octanol--aqueous partition, distribution, and ionization coefficients by reversed-phase high-pressure liquid chromatography

The described simple, accurate, and precise reversed-phase high-pressure liquid chromatographic procedure is in excellent agreement with 1-octanol shake-flask partition or distribution coefficients over a 3.5 log range. A chemically bonded octadecylsilane support is persilated and coated with 1-octanol. With 1-octanol-saturated buffers as mobile phases, a stable baseline (compared to 1-octanol adsorbed on silica) is obtained rapidly, and the log relative retention times are highly correlated with unit slope to log distribution or partition coefficients obtained from the classical shake-flask procedures. Only relatively basic, unhindered pyridines deviate, probably because of binding with residual silinol sites. In addition, if the apparent pKa or pKab of an ionizable compound lies within the pH operating range of the column support, the apparent pKa or pKab usually can be determined simultaneously with log P by measuring the log distribution coefficient at several pH values. The procedure gives rapid results, requires little material, and can tolerate impurities.