TLC--densitometric method for qualitative analysis of betamethasone and its related compounds in pharmacautical preparations.

A new simple and rapid TLC-densitometric procedure for the separation and identification of betamethasone and its related substances, betamethasone-17,21-dipropionate, betamethasone-17-valerate, betamethasone-21-valerate and also betamethasone disodium phosphate was developed. One of the chromatographic systems proposed in this study, which has been satisfactory applied in separation of four pairs of examined compounds was silica gel 60F254 (E. Merck, Art. 1.05554) and a mixture containing chloroform-methanol-acetic acid (99.5%) in volume composition 28:5:0.5. Densitometric measurements were done using densitometer TLC Scanner 3 at 246 nm. The proposed method was checked in terms of its specificity for the determination of betamethasone-17,21-dipropionate and betamethasone disodium phosphate in commercially available products containing both compounds, separately, as active ingredients. The results showed that the method is suitable for qualitative analysis of betamethasone derivatives in simple and combined pharmaceuticals in various dosage forms e.g., lotion and injection solution. It also can be applied in quality control of pharmaceutical formulations of betamethasone and its related compounds in form of salts and esters.