RESUMEN
This paper describes a HPLC method for the determination of Pidotimod (3-L-pyroglutamyl-L-thiazolidine-4-carboxylic acid; PGT/1A), a new biological response modifier, in plasma. The column was an Aminex Ion Exclusion HPX 874 with a PRP precolumn, the mobile phase was 0.05% sulfuric acid-acetonitrile (88:12, v/v), the flow rate was 0.6 ml/min, the detection wavelength was 210 nm. Plasma (1 ml) was added with internal standard (Oxiracetam, concentration 400 micrograms/ml) (50 microliters) and 35% perchloric acid (100 microliters). The supernatant (0.5 ml) was added with mobile phase (0.5 ml) and, after centrifugation, injected into the column. The retention times of Pidotimod and Oxiracetam were 16.5 and 13.8 min. respectively. The method was validated for recovery, accuracy and reproducibility. The results after oral administration of 800 mg of Pidotimod in male volunteers were also given. This method is better than that previously described because it utilizes an internal standard and reaches a lower detection limit.