Estimation of the percolation thresholds in dextromethorphan hydrobromide matrices

Area of Science:

• Pharmaceutical Sciences
• Materials Science
• Physical Chemistry

Background:

• Percolation theory, applied in pharmaceuticals since 1987, offers insights into chaotic systems.
• Understanding the percolation threshold is vital for improving solid dosage form design.
• The percolation threshold signifies the concentration at which a substance first forms a continuous cluster.

Purpose of the Study:

• To estimate the percolation thresholds of dextromethorphan hydrobromide (HBr) within Eudragit RS-PM inert matrices.
• To determine various percolation thresholds (site, site-bond, swelling) for the Eudragit RS-PM excipient.
• To validate findings against previous studies on similar pharmaceutical matrices.

Main Methods:

• Estimation of drug percolation threshold based on total porosity.
• Scanning Electron Microscopy (SEM) to analyze matrix morphology.
• Determination of site, site-bond, and swelling percolation thresholds for the Eudragit RS-PM excipient.

Main Results:

• The drug percolation threshold for dextromethorphan.HBr was found to be 0.3691+/-0.0541 (P=0.05) of total porosity, corresponding to 23-36% w/w drug.
• SEM micrographs supported the estimated drug percolation range.
• Distinct percolation thresholds were identified for Eudragit RS-PM: site (10-20% v/v), site-bond (29.5-34% v/v), and swelling (34.3-46.9% v/v).

Conclusions:

• The estimated percolation thresholds provide critical data for designing dextromethorphan.HBr solid dosage forms.
• The findings for Eudragit RS-PM align with previous research using different active pharmaceutical ingredients.
• This study reinforces the utility of percolation theory in optimizing pharmaceutical formulations and predicting material properties.