Development, Validation, and Application of a Highly Sensitive RP-HPLC Method for the Determination and Release...

Levonorgestrel (LNG), a synthetic progestin containing implants, has emerged as one of the most reliable, effective, and long-acting reversible contraceptive (LARC) methods for preventing unintended pregnancies. The current study aimed to develop and validate a simple, rapid, and highly sensitive reverse-phase high-performance liquid chromatography (HPLC) technique for the quantification and release profile comparison of LNG from different silicone-based LARC implants.

All the analysis was performed using HPLC equipped with UV/UV-VIS detector with the help of Waters C18 column of 250 × 4.6 mm dimension, 5 μm sized particle with mobile phase consisting of water and acetonitrile in the ratio of 30:70 (v/v%) at room temperature and 1 mL/minute flow rate, injection volume of 50 μl with the detection wavelength of 240 nm. The developed method was then validated as per International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines and then the validated method was used successfully to quantify LNG and for a comparative release profile study of two marketed implants, Femiplant and Sino-implant (II). The obtained release data were assessed and compared using fit factors (f₁ & f₂) to compare one formulation with another.

All parameters met the limits according to ICH guidelines. The total time needed for analysis was 12 minutes, having LNG eluting with a retention time of 5.8 min (± 0.2). The average LNG content was obtained to be 98.52 to 101.32% (± 0.05%). From the release kinetic study, f₁ and f₂ values of Femiplant against Sino-implant (II) determined was 10 and 62, respectively, both of which meet the acceptable limits.

The devolved method was straightforward and quick for any sample preparation, which could be used for routine analysis, in-process quality control analysis, and stability study analysis, among others. Moreover, Femiplant presented similar release kinetics compared to the World Health Organization prequalified implant Sino-implant (II), thereby having similar bioavailability and ensuring the consistent therapeutic effect of both implants.