A study of ofloxacin and levofloxacin photostability in aqueous solutions

Abstract

IntroductionOfloxacin ((±)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H-pyrido [1,2,3-de] [1,4] benzoxazine-6-carboxylic acid) is a second generation fluoroquinolone. This chemotherapeutic agent is often used for treatment of infections caused by Gram-negative and atypical bacteria [1][2][3]. Ofloxacin is a racemate of two enantiomers, (R)-(+)-ofloxacin and (S)-(-)-ofloxacin (levofloxacin). Antibacterial activity of levofloxacin is 8-128 times higher than that of R-(+)-ofloxacin and two times higher than that of racemic mixture [4]. The situation that one of the enantiomers (eutomer) is more active than the other (distomer) is relatively common in pharmacology. It is estimated that 40% of available drugs are chiral compounds and 25% are used as pure enantiomers. Administration of drugs in the form of a pure enantiomer is much more benefi cial for many reasons. It is possible to use a lower dose, thus reducing the risk of side effects or overdosing. It should be noted that even if distomer is inactive it is still metabolized by the liver. Its elimination from the commercial formulation allows to relieve the organ ABSTRACT Introduction. The photostability is one of the most important properties of drugs. A comprehensive study of ofloxacin (OFX) and levofloxacin (LVX) photostability in aqueous solutions was performed. Ofloxacin is a chemotherapeutic agent belonging to the second generation fluoroquinolones and is a racemate of (R)-(+)-ofloxacin and (S)-(-)-ofloxacin (LVX).Material and Methods. Samples of OFX and LVX were subjected to stress conditions of UV irradiation using a mercury-vapor lamp. The study involved development of enantioselective high-performance liquid chromatography (HPLC) and high-performance capillary electrophoresis (HPCE) methods for separation of OFX enantiomers and their degradation products. These methods were used to monitor the degradation process of OFX and LVX under irradiation and to determine the kinetics of degradation of these antibacterial agents. Moreover, the identifi cation of photoproducts was also attempted. The structure of the main photoproducts was examined by mass spectrometry (MS). Results and Conclusions. Using HPLC method it was possible to observe two products of OFX degradation and only one for LVX, while using HPCE method eight products of OFX degradation and six of LVX were observed. Some of the photoproducts retain character of optically active compounds. The trend of the photodegradation of both tested compounds was described by autocatalytic reaction proceeding according to the Prout-Tompkins model. Some of the products of the decomposition catalyze this reaction. The rate of degradation was similar for both enantiomers but t0.5 was slightly longer for LVX than OFX. Based on MS experiments the photodegradation products of the studied fluoroquinolones and possible pathways of UV induced decay were identifi ed.

Green approach for tracking the photofate of ciprofloxacin and levofloxacin in different matrices adopting synchronous fluorescence spectroscopy: a kinetic study

“…Wastewater treatment via photocatalysis for the efficient removal of CIP and LEV was a subject of concern in many articles, whereas the review articles presented by Shurbaji et al [1] and Saya et al [24] represent a good deal to these researches. However, analytical methods proposed for simultaneous estimation of either drug with its photodegradation products are limited, and usually employ high-performance liquid chromatography coupled with mass spectrometry (HPLC/MS) [25–28]. Even though it has remarkable advantages, many limitations hinder the use of HPLC/MS widely: it requires experienced trained analysts for its operation, has a high cost in terms of analysis and maintenance, only employs volatile buffers and consumes large volumes of organic solvents contradicting basic principles of green chemistry [29].…”