A normal-phase high-performance thin-layer chromatographic (HPTLC) method has been established for simultaneous quantitative determination of diclofenac sodium and paracetamol in a pharmaceutical formulation and in bulk drug powder. The analysis was performed on silica gel 60F
HPTLC plates with toluene-ethyl acetate-methanol-formic acid, 5.0 + 4.0 + 1.0 + 0.01 (
), as mobile phase. Detection and quantitation were performed densitometrically at
= 260 nm. Aceclofenac was used as the internal standard. Responses of diclofenac sodium standard and paracetamol standard were linear functions of concentration in the ranges 30–800 ng μL
and from 300–2000 ng μL
, respectively. The method was validated to determine its accuracy and precision. Accuracy was checked by conducting recovery studies; average recovery from the pharmaceutical preparation was 99.57% for diclofenac sodium and 100.51% for paracetamol. This HPTLC method developed for simultaneous quantitative determination of diclofenac sodium and paracetamol in pharmaceutical preparations is simple, rapid, and precise and can be used for routine quality control. The method was also used to determine the amounts of diclofenac sodium and paracetamol in a mixture of their respective bulk drug powders.