HPLC Determination of Dimethyl-4,4'-Dimethoxy-5,6,5',6' Dimethylene Dioxybiphenyl-2,2'-Dicarboxylate (DDB) and Co-Adminstered Diuretics as an Extemporaneous Mixture in Human Plasma

Background: Diuretics are co-adminstered with hepatoprotectant drugs for the treatment of oedema and ascitis in patients suffering from hepatic cirrhosis.This work presents an accurate and simple method for the in vivo analysis of Dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylenedioxybiphenyl-2,2'-dicarboxylate (DDB), a hepatoprotectant drug, with hydrochlorothiazide (HCT) and amiloride hydrochloride (AM) diuretics in human plasma using HPLC. Methodology/Principal Findings: The separation was achieved on Spheri-5 RP-8 (5μ) and Spheri-5 RP-18 (5μ) columns (220 X 4.6 mm i.d.) using 0.02 M disodium hydrogen phosphate, 0.12% w/v sodium laurylsulfate, 0.1% v/v triethylamine adjusted to pH 4 and acetonitrile in a ratio 65:35 v/v as mobile phase. The separation was carried out at ambient temperature with a flow rate of 1.0 mL min-1. Quantitation was achieved with UV detection at 278 nm based on peak area with linear calibration curves at concentration ranges 0.03- 30 μg mL ^-1 for HCT and 0.05- 30 μg mL ^-1 for both AM amd DDB. Conclusions: The proposed method was successfully applied to the determination of the investigated drugs in human plasma sample obtained from a healthy male volunteer four hours after single oral dose administration of the three drugs. The proposed method was validated in terms of linearity, accuracy, precision, limits of detection and quantitation and other aspects of analytical validation.