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Cloud point of nonionic surfactants: modulation with pharmaceutical excipients
G C Na1, B O Yuan, H J Stevens
1Nycomed Amersham Imaging, Wayne, Pennsylvania 19087-8630, USA. george.na@us.nycomed-amersham.com
Pharmaceutical Research
|May 5, 1999
Summary
The cloud point of nonionic surfactants can be increased using specific additives. Both nonionic and ionic compounds effectively raise surfactant cloud points in liquid formulations.
Area of Science:
- Physical Chemistry
- Formulation Science
Background:
- Nonionic surfactants are crucial in various liquid formulations.
- Understanding and controlling their cloud point is essential for stability and performance.
Purpose of the Study:
- To determine the cloud point of diverse nonionic surfactants.
- To identify compounds that can elevate surfactant cloud points in liquid formulations.
Main Methods:
- Cloud points were visually assessed in a water bath.
- Organic compounds, including pharmaceutical excipients, were screened for their effect on poloxamine 908 cloud point.
- Effective cloud point boosters (CPBs) were tested on additional surfactants.
Main Results:
- Numerous compounds were identified as effective cloud point boosters (CPBs).
- CPBs were categorized as nonionic (e.g., poly(ethylene glycols), alcohols, cyclodextrins) or ionic (e.g., charged surfactants, phospholipids, bile salts).
- Nonionic CPBs were effective at molar concentrations, while ionic CPBs were effective at millimolar concentrations.
Conclusions:
- The cloud point of nonionic surfactants in liquid formulations is modifiable.
- Strategic selection of excipients allows for the modulation of surfactant cloud points.