Quantification of dextromethorphan hydrobromide and clemastine fumarate in pharmaceutical caplets, gelcaps, and tablets by HPTLC with ultraviolet absorption densitometry

An instrumental quantitative high performance thin-layer chromato-graphic (HPTLC) method, with automated sample application on to silica gel plates with fluorescent indicator and UV-absorption scanning densitometry of fluorescence-quenched zones of samples and standards, has been developed for determination of the cough suppressant dextro-methorphan hydrobromide (DH) in solid caplets and liquid gelcaps and the antihistamine clemastine fumarate (CF) in tablets. Multiple samples of the three dosage forms were analyzed to confirm agreement between content of the active ingredients and label declarations. The accuracy of the analyses was validated by performing recovery studies with preanalyzed samples fortified with the analytes; precision was determined by analyzing replicate samples. The amount of DH in the analyzed caplets and gelcaps ranged from 100 to 114% of the label values, precision ranged from 1.2 to 1.9% relative standard deviation (RSD), and recovery of spiked samples averaged 99.4%. For CF, tablets assayed at 99.0–103% relative to the label value, precision was 2.2% RSD, and recovery from a spiked sample was 97.9%.