Purpose: To develop new selective, precise, and accurate methods for the simultaneous determination of chlorpheniramine maleate (CHP) and dexamethasone (DX) in the presence of methyl and propyl paraben in phenadone syrup.

Methods: In the first two methods, the predictive abilities of principal component regression (PCR) and partial least squares (PLS), respectively, were examined for the analysis of the quaternary mixture. The third method, high performance thin layer chromatography (HPTLC)-densitometric method, was based on the separation of the mixture on silica gel plates using chloroform: methanol (93:7, v/v) as a mobile phase.

Results: All the proposed methods were successfully applied to the analysis of raw materials and dosage form. For PCR method, recovery of chlorpheniramine maleate and dexamethasone in the dosage form was 98.89 ± 1.736 and 102.36 ± 1.86 %, respectively while for. PLS method, recovery of chlorpheniramine maleate and dexamethasone was 98.94 ± 1.69 and 102.33 ±1.84, respectively. On the other hand, recovery of the two analytes by HPTLC method was 100.72 ± 1.05 and 102.29 ± 3.98, respectively. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by a reported HPLC method.

Conclusion: The proposed methods are fast, accurate and specific, and can be applied for the quantitative determination of the two analytes without interference from added excipient, thus obviating the need for preliminary extraction of analytes from the pharmaceutical formulation. Thus, they are suitable for use in quality control (QC) laboratories and pharmaceutical industry