Validation of a UV-spectrophotometric method for ivermectin quantification

JUAN CANDELA; GALLO LOREANA; GONZALEZ VIDAL, NOELIA

Congreso; 7ma Reunión Internacional de Ciencias Farmacéuticas (RICiFa 2023); 2023

Ivermectin (IVM) constitutes a poorly soluble drug in water (Class II)1. According to USP2 and Farmacopea Argentina3, the use of toxic solvents, as acetonitrile4 and methanol5, is necessary to quantify this drug by HPLC methodology. In order to obtain a simpler methodology for IVM quantification and avoid the use of organic solvents, UV-spectrophotometry was validated in accordance with International Conference on Harmonisation (ICH) guidelines6. The IVM solutions were prepared in two different media: a mixture of water and ethanol (WE, 50:50) and a sodium phosphate buffer (PB) solution (0.01 M), with 0.5% (w/v) of sodium lauryl sulphate (SLS), adjusted to pH 7.0. The quantification was performed at the maximum absorbance wavelength of IVM in each media, 244 and 245 nm, respectively, with a calibrated UV spectrophotometer (Varian Cary 50 Conc, Varian Instruments, Australia). Tablet matrix (M) was composed by mannitol, sodium croscarmellose, colloidal silicon dioxide, magnesium stearate, strawberry essence, and aspartame. The validation scheme was developed to evaluate linearity and range, limit of detection (LOD) and quantification (LOQ), specificity, accuracy, and precision. Statistical analysis was conducted with RStudio software (version 1.4.1106).The obtained calibration curves were y = 34.652 x + 0.0216 (concentration range 5.1 - 30 µg/ml, Coefficient of Determination (R2) = 0.9941) for WE, and y = 34.158 x + 0.0093 (concentration range 0.8 - 40.6 µg/ml, R2 = 0.9993) for PB. The linearity of the methods was confirmed by the high value of R2. The LOD estimated for WE medium was 0.0001845 mg/ml, while for PB was 0.0000728 mg/ml. The LOQ was 0.00056 mg/ml and 0.00022 mg/ml, for each media, respectively. Specificity was assessed by comparison of IVM spectra with relation to the mixture IVM+M, and it was observed that the matrix did not interfere with the quantification of the analyte at selected wavelengths. There were no significant differences in the absorbances of IVM compared to IVM+M (p> 0.05). Accuracy was measured in terms of recovery (%) with respect to the theoretical amount, and evaluated at selected concentrations (0.005, 0.025 and 0.05 mg/ml). The obtained results (between 96.3% and 101.3% in both media) demonstrated an excellent accuracy. Intraday precision was assessed at previously selected concentrations. Optimal results were obtained for both media, expressed as the Relative Standard Deviation (RSD%), since they were lower than 2% (0.17 to 1.62%). Similarly, satisfactory results (RSD