Stability-indicating HPLC method for acyclovir and lidocaine in topical formulations

Area of Science:

• Analytical Chemistry
• Pharmaceutical Analysis
• Chromatography

Background:

• Topical formulations containing acyclovir and lidocaine require robust analytical methods for quality control.
• Assessing drug penetration and stability in topical applications is crucial for efficacy and safety.

Purpose of the Study:

• To develop and validate a stability-indicating HPLC assay for simultaneous determination of acyclovir and lidocaine in topical formulations.
• To evaluate the method's ability to detect analytes in human skin samples and assess extraction efficiency.

Main Methods:

• High-Performance Liquid Chromatography (HPLC) with a C18 column and gradient elution.
• Ultra-Performance Liquid Chromatography-Time of Flight Mass Spectrometry (UPLC-TOF/MS) for impurity profiling.
• Method validation including linearity, precision, repeatability, and robustness assessments.

Main Results:

• The HPLC method achieved excellent separation of acyclovir and lidocaine from impurities and degradation products.
• High linearity (r² >0.9995) and low variability (<2% RSD) confirmed method accuracy and precision.
• Successful detection of analytes in skin homogenates with high extraction efficiency (≈92%) and no interference from skin leachables.

Conclusions:

• A validated, stability-indicating HPLC assay enables accurate and simultaneous quantification of acyclovir and lidocaine in topical formulations.
• The method is suitable for analyzing drug penetration in human skin, providing valuable data for topical drug development.