Estimation and Evaluation of Gabapentin and Pregabaline Anti-Epileptic Drugs in Bulk and Pharmaceutical Preparations by Eco-Friendly Bromate-Bromide Reagent

Abstract

Tow simple and sensitive spectrophotometric methods are described for the
determination of the anti-epileptic drugs (Gabapentin and Pregabaline) as apure drug
andin commercial pharmaceutical preparations. These methods involve the bromination of
the anti-epileptic drugs (Gabapentin and Pregabalin) with a well-known excess amount of
bromate-bromide mixture in acid medium as an eco friendly brominating agent followed
by the determination of unreacted bromine. The ideal conditions for the experimental
work have been studied and optimized The remaining amount of bromine is estimated by
the reaction with an excess amount of potassium iodide KI and the form edtriiodide (I -3) is
either measured directly at 350 nm and 355nmfor Gabapentin and Pregabalin (method A),
or reacted with starch solutionand the measurement of the colored starch-iodine complex
at 520nm and 555 nm for Gabapentin and Pregabal in respectively (method
B).Absorbanceversus concentration plotswere drawn and it were linear to a certain degree,
indicating that the results adheredto Beer's law over the ranges of0.30-15.0, 0.25-10.0
and2.0-10.0,0.30-6.00μg /mlfor Gabapentin and Pregabalin inboth methods, A and B. The
molar absorptivities were found to be 1.489×104, 2.853×104 and 1.524× 104,2.765×104
L/molcm for of Gabapentin and Pregabalin in method A and B respectively. Sandells
sensitivity indexes were 0.964×10-3,0.102×10-3 and 0.164×10-3,0.068×10-3 μg/cm2 for
Gabapentin and Pregabalin in both methods respectively. The proposed method has been
applied successfully for the quantitative analysis of Gabapentin and Pregabalin in pure
form and in commercial pharmaceutical preparations (capsules). There wasno interference
observed from the excipients. The results showeda good precision and accuracy using a
standard additional method and it were statistically compared with a reference method by
using the Student’s t- and F-test,showing agood agreement with the standard