Nadia M. Mostafa

Progression of Cisplatin-Induced Nephrotoxicity in a Carnitine-Depleted Rat Model

Background: This study has been initiated to investigate whether endogenous carnitine depletion and/or carnitine deficiency is an additional risk factor and/or a mechanism in cisplatin-induced nephrotoxicity and to gain insights into the possibility of a mechanism-based protection by L-carnitine against this toxicity. Methods: 60 male Sprague-Dawley rats were divided into six groups of 10 animals each and received one of the following treatments: The first three groups were injected intraperitoneally with normal saline, L-carnitine (500 mg/kg), and D-carnitine (750 mg/kg), respectively, for 10 successive days. The 4th, 5th, and 6th groups were injected intraperitoneally with the same doses of normal saline, L-carnitine and D-carnitine, respectively, for 5 successive days before and after a single dose of cisplatin (7 mg/kg). Six days after cisplatin treatment, the animals were sacrificed, and serum as well as kidneys were isolated and analyzed. Results: A single dose of cisplatin resulted in a significant increase in blood urea nitrogen (BUN), serum creatinine, malondialdehyde (MDA) and nitric oxide (NO) and a significant decrease in total carnitine, reduced glutathione (GSH) and adenosine triphosphate (ATP) content in kidney tissues. Interestingly, L-carnitine supplementation attenuated cisplatin-induced nephrotoxicity manifested by normalizing the increase of serum creatinine, BUN, MDA and NO and the decrease in total carnitine, GSH and ATP content in kidney tissues. In the carnitine-depleted rat model, cisplatin induced a progressive increase in serum creatinine and BUN as well as a progressive reduction in total carnitine and ATP content in kidney tissue. Histopathological examination of kidney tissues confirmed the biochemical data, i.e. L-carnitine supplementation protected against cisplatin-induced kidney damage, whereas D-carnitine aggravated cisplatin-induced renal injury. Conclusion: Data from this study suggest that: (1) oxidative stress plays an important role in cisplatin-induced kidney damage; (2) carnitine deficiency should be viewed as an additional risk factor and/or a mechanism in cisplatin-induced renal dysfunction, and (3) L-carnitine supplementation attenuates cisplatin-induced renal dysfunction.

Validated Stability-Indicating Spectrophotometric Methods for the Determination of Cefixime Trihydrate in the Presence of its Acid and Alkali Degradation Products

Five simple, accurate, precise, and economical spectrophotometric methods have been developed for the determination of cefixime trihydrate (CFX) in the presence of its acid and alkali degradation products without prior separation. In the first method, second derivative (2D) and first derivative (1D) spectrophotometry was applied to the absorption spectra of CFX and its acid (2D) or alkali (1D) degradation products by measuring the amplitude at 289 and 308 nm, respectively. The second method was a first derivative (1DD) ratio spectrophotometric method where the peak amplitudes were measured at 311 nm in presence of the acid degradation product, and 273 and 306 nm in presence of its alkali degradation product. The third method was ratio subtraction spectrophotometry where the drug is determined at 286 nm in laboratory-prepared mixtures of CFX and its acid or alkali degradation product. The fourth method was based on dual wavelength analysis; two wavelengths were selected at which the absorbances of one component were the same, so wavelengths 209 and 252 nm were used to determine CFX in presence of its acid degradation product and 310 and 321 nm in presence of its alkali degradation product. The fifth method was bivariate spectrophotometric calibration based on four linear regression equations obtained at the wavelengths 231 and 290 nm, and 231 and 285 nm for the binary mixture of CFX with either its acid or alkali degradation product, respectively. The developed methods were successfully applied to the analysis of CFX in laboratory-prepared mixtures and pharmaceutical formulations with good recoveries, and their validation was carried out following the International Conference on Harmonization guidelines. The results obtained were statistically compared with each other and showed no significant difference with respect to accuracy and precision.

SELECTIVE CHROMATOGRAPHIC METHODS FOR THE DETERMINATION OF ROSUVASTATIN CALCIUM IN THE PRESENCE OF ITS ACID DEGRADATION PRODUCTS

Two accurate and sensitive stability-indicating methods for the determination of rosuvastatin calcium in the presence of its acid degradation products are presented. The first method utilizes quantitative spectrodensitometric evaluation thin-layer chromatography (TLC) of rosuvastatin calcium in the presence of its acid degradation products, using ethyl acetate/methanol/ammonia (7:3:0.01, by volume) as a mobile phase. Chromatograms are scanned at 245 nm. This method analyzes rosuvastatin calcium in a concentration range of 0.6–3.4 µg/band with mean percentage recovery of 99.78 ± 1.42. The second method is a high-performance liquid chromatography (HPLC) method for the simultaneous determination of rosuvastatin calcium in the presence of its acid degradation products. The mobile phase consists of water/acetonitrile/methanol (40:40:20, by volume). The standard curve of rosuvastatin calcium shows a good linearity over a concentration range of 10–60 µg mL−1 with mean percentage recovery of 100.22 ± 0.86. These methods were successfully applied to the determination of rosuvastatin calcium in bulk powder, laboratory-prepared mixtures containing different percentages of the acid degradation products, and pharmaceutical dosage forms. The validity of results was assessed by applying standard addition technique. The results obtained were found to agree statistically with those obtained by a reported method, showing no significant difference with respect to accuracy and precision.

Stability-Indicating Spectrofluorometric Method for the Determination of Some Cephalosporin Drugs via Their Degradation Products

A stability-indicating spectrofluorometric method was investigated for the determination of three cephalosporin drugs, namely, cefpodoxime proxetil (CPD), cefixime trihydrate (CFX), and cefepime hydrochloride (CPM), via their acid and alkali degradation products. The three drugs were determined via their acid degradation at 432, 422, and 435 nm using an excitation wavelength of 310, 330, and 307 nm for CPD, CFX, and CPM determination, respectively, and via their alkali degradation at 407, 411, and 405 nm using an excitation wavelength of 310, 305, and 297 nm for CPD, CFX, and CPM determination, respectively. Linearity was achieved in the ranges of 0.35-3.50, 0.4-4.0, and 0.3-3.0 μg/mL for the acid degradation products of CPD, CFX, and CPM, respectively, and in ranges of 0.05-0.5, 0.1-1.0, and 0.08-0.80 μg/mL for the alkali degradation products of CPD, CFX, and CPM, respectively. The method was validated for various parameters according to International Conference on Harmonization guidelines. The method was successfully applied for the determination of these cephalosporin drugs in pharmaceutical dosage forms with good accuracy and precision. The results obtained by the proposed spectrofluorometric method were compared with good agreement to the official HPLC method.