Green Alternatives in Pharmaceutical and Bioanalytical Analysis of TDM Required Drugs: Procainamide

Introduction: In drug analysis, using non-hazardous solvents instead of the ones harmful to humans and the environment is a green strategy to protect analysts and environmental health. Objective: Procainamide (PCA) is an antiarrhythmic drug requiring therapeutic drug monitoring (TDM) because of its narrow therapeutic window and serious side effects. Aim: The aim of this study is to develop validated green HPLC methods to be used in drug quality control and TDM analysis for PCA, thus indicating the further applicability in the analysis of TDM-required drugs, such as immunosuppressants, anti-cancer drugs, and psychiatric drugs. Methods: Human-friendly ethanol was selected as an organic solvent in the mobile phase. PCA was eluted from NUCLEODUR 100-5 C8 ec (5 μm, 150 x 4.6 mm) column by a mobile phase containing ethanol and 50 mM NaH2PO4buffer (5:95, v/v). The mobile phase flow rate was 1.0 ml min^-1, the column temperature was 35 °C, and the wavelength at the PDA detector was 278 nm. Results: Retention time for PCA was 5.0 min and 7.7 min for paracetamol as an internal standard (IS). In the green HPLC method for pharmaceutical analysis, the highest relative standard deviation (RSD) and mean recovery values were 1.32% and 98.89%, respectively. In the analysis of plasma, the sample preparation step was only smooth protein precipitation by ethanol. Thus, the bioanalytical method was fully green having a limit of detection (LOD) of 0.3 μg ml^-1 and a limit of quantification (LOQ) of 0.8 μg ml^-1. The therapeutic plasma concentration for PCA was reported in the range of 4–12 μg ml^-1. Conclusion: As a result, the green HPLC methods developed and validated in this study were selective, accurate, precise, reproducible, and trustable and have the quality for the application in pharmaceutical and TDM analysis of PCA, thus encouraging green HPLC analysis of other TDM required drugs.