Spectrofluorimetric Determination of Vigabatrin and Gabapentin in Dosage Forms and Spiked Plasma Samples Through Derivatization with 4-Chloro-7-Nitrobenzo-2-Oxa-1,3-Diazole

Abstract

A highly sensitive and specific method is proposed for the determination of vigabatrin (I) and gabapentin (II) in their dosage forms and spiked human plasma. The method is based on coupling the drugs with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole in borate buffer at pH 7.1 and measuring the resulting fluorescence at 532 nm after excitation at 465 nm. The fluorescence intensity was a linear function of the concentration of the drugs over the ranges of 1.3–6.5 and 1.7–8.5 μg/mL for I and II, respectively. Minimum detectability values were 0.54 μg/mL (4.2 × 10−6M) and 0.97 μg/mL (5.7 × 10−6M) for I and II, respectively, under the described conditions. The proposed method was successfully applied to the determination of the 2 drugs in their dosage forms, and the percent recoveries ± standard deviation (SD) were 104.53 ± 1.2 and 100.00 ± 1.32 of the label claim for I and II, respectively. The method was further applied to the determination of vigabatrin in spiked plasma samples. The percent recovery ± SD was 101.58 ± 2.68. Interference from endogenous α-amino acids was overcome through selective complexation with freshly prepared Cu(OH)2. The interference likely to be encountered from co-administered drugs, such as carbamazepine, cimetidine, clonazepam, clopazam, phenobarbital, valproic acid, and lamotrigine, was also studied. A reaction pathway is suggested.

A highly sensitive fluorimetric protocol based on isoindole formation for determination of gabapentin

“…The developed spectrouorimetric method has several advantages over the previous reported methods. The current spectrouorimetric method is characterized by high sensitivity (in ng mL À1 ) compared with Hassan et al 5 and Prasad et al 7 methods. Also, the method is cheap as it does not depend on using expensive reagent compared with Belal et al method.…”

“…1 An analytical literature survey revealed that several methods have been reported for determination of gabapentin in pure forms and pharmaceutical dosage forms including spectrophotometry, 2-4 spectrouorimetry, [5][6][7][8] high-performance liquid chromatography (HPLC), [9][10][11] gas chromatography-mass spectrometry (GC-MS), 12 capillary electrophoresis 13 and electrochemical techniques. 14 The reported spectrouorimetric methods of analysis are either suffer from low sensitivity [5][6][7] or require heating and tedious extraction procedures. 8 In addition, the chromatographic, electrophoretic and electrochemical methods require highly sophisticated instruments and/or require expensive detector which is not available in most laboratories.…”

Gabapentin Bioequivalence Study: Quantification by Liquid Chromatography Coupled to Mass Spectrometry

“…Several analytical methods have been reported for the determination of gabapentin in human plasma and biological samples. The methods are based on high-performance liquid chromatography (HPLC) with UV [6,7] or fluorescence detection [8][9][10][11][12][13], capillary electrophoresis (CE) [14,15], gas chromatography (GC) with flame ionization [16] or mass spectrometry (MS) [17][18][19], and liquid chromatography-tandem mass spectrometry (LC-MS-MS) [20][21][22][23][24][25]. The HPLC and CE methods are time-consuming because they require derivatization of gabapentin to produce a detectable chromophore.…”

Spectrscopic and Conductometric Analysis of Gabapentin

“…Gabapentin (1-(aminomethyl)cyclo-hexaneacetic acid) is a structural analogue of g-aminobutyric acid (GABA) (Scheme 1) and its action is attributed to the irreversible inhibition of the enzyme GABA-transaminase, thus preventing the physiological degradation of GABA in the brain; a secondary mechanism of a blockade for GABA uptake is also suggested 1 , it is an antiepileptic effective in the treatment of partial seizures with or without secondary generalization and is used as adjunctive therapy in patients unresponsive to or intolerant of standard antiepileptic drugs 2 . A survey of the literature reveals that there were few reported methods for the determination of gabapentin using spectrophotometric technique [3][4][5] , spectrofluorimetry 6,7 , capillary electrophoresis 8 , LC-MS 9 and HPLC 10,11 . Scheme 1.…”