Microviscosity and drug release from topical gel formulations.

Gel formulations are often used in topical drug delivery, and the drug release is controlled by two factors, the thermodynamic activity of the drug and the microviscosity of the gel. The latter property has been probed by observing the dynamic light scattering from polystyrene lattices of known particle size dispersed within Carbopol gels. The effect of gel concentration and temperature has been observed and related to the ability of the gel to release a series of salicylates.