Tropical Journal of Pharmaceutical Research

Original Research Article | OPEN ACCESS

Novel polymeric prodrugs of valproic acid as anti-epilepsy drugs: Synthesis, characterization and in-vitro evaluation

Seyyedeh Nazanin Amiryaghoubi, Mirzaagha Babazadeh

Department of Chemistry, Tabriz Branch, Islamic Azad University, Tabriz, Iran;

For correspondence:- Mirzaagha Babazadeh Email: babazadeh@iaut.ac.ir Tel:+984133396024

Received: 27 April 2015 Accepted: 15 June 2015 Published: 29 July 2015

Citation: Amiryaghoubi SN, Babazadeh M. Novel polymeric prodrugs of valproic acid as anti-epilepsy drugs: Synthesis, characterization and in-vitro evaluation. Trop J Pharm Res 2015; 14(7):1183-1189 doi: 10.4314/tjpr.v14i7.9

© 2015 The authors.
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Abstract

Purpose: To synthesize and evaluate, in-vitro, novel polymeric prodrugs of valproic acid (VPA) for anti-epileptic activity.

Methods: Homopolymer of 4-chloromethyl styrene (CMS) and its copolymers with various acrylic-type monomers such as 2-hydroxyethyl methacrylate and methyl methacrylate were prepared by free radical polymerization method. VPA was then covalently linked to the obtained polymers by treating CMS polymers with sodium valproate. All the compounds were characterized by Fourier transform infrared (FT-IR), nuclear magnetic resonance (¹H and ¹³C-NMR), elemental analyses, and gel permeation chromatography (GPC). The release of VPA from polymeric prodrugs was studied using cellophane membrane dialysis bags containing aqueous buffer solutions (pH 1, 7 and 10) at 37 ^oC. The quantity of released drug was detected by ultraviolet (UV) spectroscopy.

Results: ¹H-NMR and elemental analyses data for calculating mole composition of CMS polymers were relatively in good agreement. FT-IR and NMR data for the polymeric prodrugs showed attachment of drug substituents to phenyl rings of CMS units via methylene spacer. The drug-release profiles indicated that selective hydrolysis of ester bond between the drug and the polymer backbone is strongly dependent on polymer hydrophilicity and the pH of the hydrolysis solution.

Conclusion: The synthesized VPA polymeric prodrugs may be cost-effective compounds for release of VPA in vivo when formulated as controlled release systems.

Keywords: 4-Chloromethyl styrene, Valproic acid, Polymeric prodrugs, Controlled release, Hydrolysis