The potential of polymeric film-forming systems as sustained delivery platforms for topical drugs

ABSTRACT

Introduction: Dosing regimens requiring multiple daily applications frequently result in poor patient compliance, especially in the treatment of chronic skin diseases. Consequently, development of sustained delivery systems for topical drugs permitting less frequent dosing is of continuing interest for dermatological therapy.

Areas covered: This potential of polymeric film-forming systems (FFS), created in situ on the skin, as sustained delivery platforms for topical drug delivery is reviewed. Key formulation parameters that determine delivery efficiency are considered focussing on those that permit a drug reservoir to be established in the upper layers of the skin and/or on the skin surface from which release can be sustained over a prolonged period. The advantageous and superior cosmetic attributes of FFS (compared to conventional semi-solid formulations) that offer significantly improved patient compliance are also addressed.

Expert opinion: The promise of polymeric FFS as convenient and aesthetic platforms for sustained topical drug delivery is clear. Manipulation of the formulation allows the delivery profile to be customized and optimized to take advantage of both a rapid, initial input of drug into the skin (likely due to a transient period of supersaturation) and a slower, controlled release over an extended time from the residual film created thereafter.

Keywords:

• Dermal drug delivery
• polymeric film-forming systems
• supersaturation
• sustained delivery
• topical formulations

Article highlights.

• Optimization of the formulation of polymeric film-forming systems (FFS) permits sustained drug delivery to be achieved via the formation of a drug reservoir in or on the skin.

• The initial metamorphosis of the formulation, and consequent increase in the degree of drug saturation, enables the establishment of a drug reservoir in the upper skin layers.

• FFS prepared with hydrophobic polymers have greater skin substantivity, facilitating formation of an external drug reservoir from which sustained delivery may be achieved.

• Realization of the long-term potential of FFS as sustained, topical drug delivery systems requires proof-of-principle to be demonstrated conclusively in vivo.

• A key issue is to accomplish the desired therapeutic effect with an FFS formulation that creates an aesthetically acceptable residual polymeric film on the skin.

Acknowledgements

We thank Dr Natalie Belsey for generating the SRS images in Figure 6 and Dr Hazel Garvie-Cook for the AFM image in Figure 7.

Declaration of interest

K. Frederiksen and R.H. Guy have received research funding from LEO Pharma A/S. K Petersson is employed at LEO Pharma A/S. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.