Anodic Polaroqraphic Determination of lsradipine in Pharmaceutical Formulations

F Belal,A A Al-Majed,S Julkhuf

doi:10.3797/scipharm.aut-04-12

Abstract

The anodic behaviour of isradipine was studied using cyclic voltammetry (CV), direct current (DCt) and differential-pulse (DPP) polarography. lsradipine exhibited well-defined anodic polarographic waves over the pH range of 4–8 in Britton-Robinson buffer (BRb). At pH 6, the analytical pH, the diffusion-current constant (Id) was 2.12 ± 0.42 (n = 4). The oxidation potential is −0.10 V vs AgIAgCl reference electrode with correlation coefficients of 0.9977 and 0.9948 in the DCt and DPP modes, respectively. The current-concentration plots were rectilinear over the ranges 5–14 µg/ml and 2.4–12 µg/ml using the DCt and DPP modes, respectively. The lower detection limit was 1.12 µg/ml (3.02 x 10−6 M) adopting the DPP mode. The proposed method was applied to commercial tablets and capsules, the % recoveries were 100.52 ± 1.267 and 99.4 ± 0.87 (n = 6) for the tablets and 101.3 ± 1.57 and 100.7 ± 2.10 (n = 6) for the capsules adopting both DCt and DPP modes, respectively. The number of electrons involved in the electrode process was accomplished and a proposal of the electrode reaction was presented.

Highlights

Scheme 1: Structural formula of Isradipine. lsradipine, 4-(4-benzofurazanyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinecar-F
Reviewing the literature revealed that all the reported methods for isradipine in dosage forms and biological fluids rely on the use of chromatographic techniques such as thin layer chromatography (TLC) [4,5], GC [6-91 and HPLC [4-171
The cyclic voltammogram of isradipine (1 r IO-~M) in Britton-Robinson buffer (BRb) of pH 6 using a scan rate of 2.0 mvlsec. [Fig. I]

Summary

Introduction

Scheme 1: Structural formula of Isradipine. lsradipine, 4-(4-benzofurazanyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinecar-. The presence of the oxidizable dihydropyridine ring structure in the molecular formula of isradipine initiated the present study. Lomir tablets Batch # TI001 (2.5 mg of isradipine/tablet) Both are products of Novartis Pharma, AG, Basle, Switzerland. The cyclic voltamograph (757 VA computrace) was obtained from Metrohm (Herisau, Switzerland). It consists of a hanging mercury drop electrode in the DPP mode, a saturated AgIAgCI reference electrode and a platinum wire as the auxiliary electrode. A threeelectrode system composed of a Dropping Mercury Electrode (DME) as the working electrode, AgIAgCI reference electrode, and a platinum wire as the auxiliary electrode, was used. The solutions were purged with pure nitrogen gas for 5 min before being polarographed at room temperature

Recommended Procedure

Results and Discussion

Conclusion