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The kinetic and thermodynamic parameters of degradation of doripenem were studied using a high-performance liquid chromatography method. In dry air, the degradation of doripenem was a first-order reaction depending on the substrate concentration. At increased relative air humidity, doripenem was degraded according to the autocatalysis kinetic model. The dependence ln k = f1/T) was described by the equations ln k = 5.10 ± 13.06 − (7576 ± 4939)(1/T) in dry air and ln k = 46.70 ± 22.44 − (19,959 ± 8031)(1/T) at 76.4% relative humidity (RH). The thermodynamic parameters Ea, ΔH≠a, and ΔS≠a of the degradation of doripenem were calculated. The dependence ln k = f (RH%) was described by the equation ln k = (0.155 ± 0.077) × 10−1 (RH%) − (3.45 ± 21.8) × 10−10. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 722–728, 2012

A novel and sensitive stability-indicating RP-HPLC method for the quantitative determination of cefquinome sulfate has been developed. Chromatographic separation and quantitative determination were performed using a high-performance liquid chromatograph with UV detection. As the stationary phase a LiChroCART RP-18 column (5 microm particle size, 125 mm x 4 mm, Merck, Darmstadt, Germany) was used. The mobile phase consisted of 10 volumes of acetonitrile and 90 volumes of an 0.02 M phosphate buffer (pH = 7.0). The flow rate of the mobile phase was 1.0 mL/min. The eluents were monitored by a UV-VIS detector at 268 nm. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Significant degradation was found under basic, oxidizing stress and UV light. The developed method was validated with respect to linearity, accuracy, precision and robustness.

Eplerenone was subjected to the influence of ionizing radiation in the form of a high-energy electron beam (25–400 kGy), high temperature (90°C RH 0% and 60°C RH 76.4%), and light (6 mln lux h). An HPLC method was used to determine the content of eplerenone and to establish the impurity profile of all samples. As eplerenone was found to be a compound of great resistance to the above stress factors with the exception of high doses of ionizing radiation (≥200 kGy) when its degradation was above 1%, it is possible to sterilize eplerenone by radiation method with the standard dose of 25 kGy. Based on the analysis of impurities and degradation products, the mechanism of radiodegradation was demonstrated to differ from the mechanisms of photo- and thermodegradation. The observation that the DSC curves for the nondegraded and degraded samples of eplerenone were significantly different only under exposure to the electron beam confirmed the applicability of DSC for studies of radiolytic degradation of eplerenone.

The influence of pH and temperature on the stability ofN-[(piperidine)methylene]daunorubicin hydrochloride (PPD) was investigated. Degradation was studied using an HPLC method. Specific acid-base catalysis of PPD involves hydrolysis of protonated molecules of PPD catalyzed by hydrogen ions and spontaneous hydrolysis under the influence of water zwitterions, unprotonated molecules, and monoanions of PPD. The thermodynamic parameters of these reactions, energy, enthalpy, and entropy, were calculated. Also, the stability of daunorubicin and its new amidine derivatives (piperidine, morpholine, pyrrolidine, and hexahydroazepin-1-yl) in aqueous solutions was compared and discussed.

The risk of cardiovascular diseases is closely related to hypertension, high cholesterol levels, and diabetes. When these risk factors appear together they are referred to as a metabolic syndrome. In the treatment of cardiovascular diseases, a combination of antihypertensive, hypolipemiant, and antidiabetic drugs is often applied. Diuretics (chlortalidone, hydrochlorothiazide, etc.) and angiotensin II receptors antagonist (sartans) are used to control hypertension, whereas statins (fluvastatin, simvastatin, etc.) are used to reduce cholesterol levels. This review is concerned with methods for the analysis of sartans in various matrices, such as pharmaceutical formulations, environmental and biological samples, and discusses the current status of stability studies of sartans . It also presents analytical methods for the simultaneous determination of sartans, diuretics, and statins. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:2–28, 2014