Development and Validation of Stereo Selective Method for the Separation of Razoxane Enantiomers in Hydrophilic Interaction Chromatography.

A novel sensitive and high throughput chiral hydrophilic interaction chromatographic (HILIC) method was developed to separate razoxane enantiomers namely levrazoxane (R-isomer) and dexrazoxane (DEX) in pharmaceutical active ingredient samples. A systematic chiral chromatographic screening system was employed in using multiple HPLC chromatographic modes on various polysaccharide based chiral columns to obtain a potential separation between enantiomers. HPLC separation was achieved using a mobile phase of aqueous 10 mM ammonium bicarbonate and mixture of organic modifiers (70/30, v/v) in the ratio of (5/95, v/v) on an immobilized polysaccharide based chiral stationary phase namely CHIRALPAK IE-3. The chromatographic resolution between the enantiomers was found to be not <8 in the developed method. The values of the limit of detection and limit of quantification of DEX and levrazoxane were found to be 0.0037, 0.011 and 0.0043, 0.013 µgmL-1, respectively. The validated method yielded good results regarding precision, linearity, selectivity and found to be superior in sensitivity when compared to reported method for the accurate quantification of undesired enantiomer.

A sensitive and specific procedure for quantitation of ADR-529 in biological fluids by high-performance liquid chromatography (HPLC) with column switching and amperometric detection.

An HPLC method using electrochemical detection (ED) has been validated for the determination of ADR-529 in plasma and urine using ICRF-192 as an internal standard (IS). Prior to storage and quantitation, both plasma and urine samples require acid stabilization. Acidified plasma samples were prepared for HPLC using a two column solid-phase extraction (SPE). An aliquot of buffered plasma (i.e., pH 6-7) was first deproteinated and desalted on a C-18 SPE column. The analytes were then eluted onto a C-8 SPE column where retention and selective cleanup were achieved in the cation-exchange mode via silanol interactions. Acidified urine samples were diluted in acetonitrile prior to injection. The HPLC system for plasma and urine samples employed two narrow-bore silica columns used in the weak cation-exchange mode and separated by a switching valve. To prohibit late-eluting peaks from passivating the glassy carbon working electrode, a heart-cut containing ADR-529 and the IS was vented from the first silica column to the second using an automated switching valve. Amperometric detection at an oxidation potential of +1050 mV vs a Ag/AgNO3 reference electrode was used. Linearity was validated between 5 and 500 ng/ml in plasma and between 2 and 100 micrograms/ml in urine. Imprecision and percentage bias were typically less than 10% for both plasma and urine controls throughout their respective dynamic ranges. The absolute recoveries for ADR-529 and the IS from plasma were greater than 95%. This method is being successfully applied to the pharmacokinetic/dynamic evaluation of ADR-529 in animals and humans.

The hydrolysis activation of the doxorubicin cardioprotective agent ICRF-187 [+)-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane).

ICRF-187 [(+)-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane] has shown promise [Speyer et al., N. Engl. J. Med. 319, 745 (1988)] as a cardioprotective agent against what may be an iron-based doxorubicin (Adriamycin)-induced cardiotoxicity. ICRF-187 likely exerts its action through its rings-opened hydrolysis product, a compound that has an EDTA-type structure and, likewise, strongly binds metal ions. The hydrolysis of ICRF-187 was followed spectrophotometrically in the ultraviolet and was shown to be pseudo-first-order over a wide pH range. The hydrolysis mechanism was shown to have a hydroxide-catalyzed path and a pH-independent path similar to the hydrolysis of other imides. The anionic form of ICRF-187 (with a pKa of 9.6 at 37 degrees C) was resistant to hydroxide attack. The kinetically, spectroscopically and potentiometrically determined pKa values were all in excellent agreement and thus provided a test of the mechanism. Each imide group underwent hydrolysis and ionization independently of the other. The rate of ICRF-187 hydrolysis was also followed by observation of the removal of Cu2+ from a Cu2(+)-doxorubicin complex by the ICRF-187 hydrolysis product.