Drug-containing, colloidal liquid aphrons are dispersed in a solution of a film-forming polymer.

The solution is dried, causing the polymer film to form, trapping the aphrons in the polymer matrix.

Subsequent dissolution of the polymer film by water or body fluids releases to aphrons to deliver the drug(s) they contain in a soluble, highly-dispersed form.

TFE is a means of trapping oils and oil-soluble materials, such as drugs, in a polymer matrix in the form of aphrons. The principle use of TFE is in the controlled release of oil-soluble drugs. The drug is released in the form of a solution or dispersion in the aphrons. TFE offers the following advantages over other forms of controlled release:

· The drug is released in an easier-to-absorb form.
· The choice of polymer is wide and varied compared to other polymer-based devices.
· There is flexibility of size and shape and form to a greater extent than in other devices.

· It can take advantage of the beneficial formulation and problem-solving abilities of Polyaphron Dispersions (See ‘ATD’).
· TFE is relatively cheap and simple to make.
· TFE can be used for dermal routes (skin patches, wound dressings), oral (lozenges, buccal patches, depot).
· TFE can also be used to encapsulate and protect vulnerable drugs and other substances of pharmaceutical interest such as enzymes.
· It is free from patent constraints (other than our own patents).

TFE is takes advantage of the fact that Polyaphron Dispersions are extremely stable and strong enough to resist the powerful forces generated in film-forming polymers during the film-forming stage (when conventional dispersions, such as emulsions, are ripped apart).

Drug-containing, colloidal liquid aphrons are dispersed in a solution of a film-forming polymer.

One form of TFE application is illustrated in the diagram below.