When it is too much: Identifying butamben excess on the surface of pharmaceutical preformulation samples by Raman...

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems
• Materials Science

Background:

• Butamben, a topical local anesthetic, presents formulation challenges in lipid-based drug delivery systems (DDS) due to its hydrophilic excipient affinity.
• Developing stable nanostructured lipid carriers (NLC) necessitates careful selection of medium polarity excipients to ensure active pharmaceutical ingredient (API) solubility and drug loading.

Purpose of the Study:

• To screen and identify optimal excipients for stable Butamben NLC formulations.
• To evaluate API solubilization and distributional homogeneity within NLCs.
• To establish formulation parameters for maximizing drug upload and stability.

Main Methods:

• Comprehensive screening of various excipients for Butamben solubilization.
• Microscopic evaluation using Raman mapping to assess distributional homogeneity index (DHI).
• Design of Experiments (DoE) to model excipient interactions and optimize formulation parameters.

Main Results:

• Excipient selection significantly impacts API solubility and NLC stability.
• Raman mapping and DHI analysis revealed optimal excipient combinations for homogeneous API distribution.
• DoE models (R² > 0.8824) elucidated excipient interactions, with API concentration above 30% (w/w) indicating homogeneity in miscible systems.
• Concentration vs. mean image scores provided an alternative method to determine API saturation limits.

Conclusions:

• Medium polarity excipients are crucial for stable Butamben NLC formulations.
• A combination of solubilization screening, Raman mapping, DHI analysis, and DoE is effective for optimizing NLC formulations.
• The study provides a framework for developing robust lipid-based drug delivery systems for challenging APIs.