Salicylic acid

The objective of this work was to develop a simple, sensitive, accurate, precise and reproducible high performance liquid chromatography (HPLC) method for the determination of salicylic acid in pharmaceutical dosage forms. Shimadzo Prominance model L20 AD HPLC system equipped with SPD 20A UV-Vis detector was used for the analysis. The separation was done on RESTEX allure C18 column (3 μm, 15 cm × 4.6 mm), for an isocratic elution a mixture of water, methanol and glacial acetic acid (65:35:1, v/v) mobile phase at a wavelength of 254 nm. The flow rate was 1.0mL/min. The RP-HPLC method developed for analysis of salicylic acid was validated with respect to specificity, selectivity, linearity, accuracy, precision and robustness as per the ICH guidelines. The retention time of salicylic acid was 7.575 min. The linearity was established over the concentration ranges of 50-350 μg/mL with correlation coefficients ( r2) 0.999.  The percentage accuracy of salicylic acid ranged from 99.76 -101.66%. The relative standard deviation values for intra-day and inter-day precision was lower than 2.0% and the assay result was found to be in the range 99.57-101.32%. Salicylic acid was subjected to stress conditions such as neutral, acidic, alkaline, oxidation and photolysis degradations as per ICH guidelines. The degradation studies revealed that the drug was found to degrade maximum (1.67%) in alkaline degradation conditions and was highly resistant towards neutral, acidic, oxidative and photolytic degradation conditions.

Inflammation is a complex biological response of vascular tissues to harmful stimuli. The stimulus may be thermal (heat or cold), chemical (foreign substances, foreign organisms, drugs), or mechanical (trauma). Anti-inflammatory agents are the agents which relieves the inflammation. Amino acids L-tyrosine was refluxed in presence of thionyl chloride and methanol for 8 hrs to form its methyl ester hydrochloride(a). Compound (a) and taurine were refluxed with Salicylic acid in 30 % NaOH solution for 2 hrs and neutralized with conc. hydrochloric acid to precipitate target compounds (b, c). These compounds were characterized on basis of melting point, TLC (Rf value), IR and 1H NMR spectra and evaluated for analgesic and anti-inflammatory activity. Target compound (b) was found to be most active with 96.3 % protection for analgesic and anti-inflammatory activity.