Film-Forming Systems for Dermal Drug Delivery
Film-forming formulations represent a novel form of sustained release dermatic products. They are applied to the skin as a liquid or semi-solid preparation. By evaporation of the volatile solvent on the skin, the polymer contained in the formulation forms a solid film. Various film-forming formulations were tested for their water and abrasion resistance and compared with conventional semi-solid formulations. Penetration and permeation studies of the formulations indicate a potential utility as transdermal therapeutic systems. They can be used as an alternative to patch systems to administer a variety of drugs in a topical way and may provide sustained release characteristics.
Download the full article here: Film-Forming Systems for Dermal Drug Delivery
or continue reading here: Pünnel, L.C.; Lunter, D.J. Film-Forming Systems for Dermal Drug Delivery. Pharmaceutics 2021, 13, 932. https://doi.org/10.3390/pharmaceutics13070932
Polymers for use in film-forming formulations
| Polymer | Properties |
|---|---|
| Carbopol (polyacrylat) | water-soluble, pH sensitive |
| Chitosan (Poly-D-Glucosamin) | water-soluble at pH < 7 |
| Crosslinked polymer layer XPL | adhesive, elastic |
| Dermacryl 79 (Carboxylates Acrylpolymer) | water-insoluble |
| Ethylcellulose | non-toxic, not irritating, anti-allergic |
| Eudragit NE (ethylacrylate methylmethacrylate copolymer) | water-insoluble, transparent, elastic, adhesive |
| Eudragit RL-100 (polymethacrylate polymere) | water-insoluble, transparent, elastic, adhesive |
| Eudragit RS-100 (polymethacrylate polymere) | water-insoluble, transparent, elastic, adhesive |
| Eudragit L30D-55 (methacrylate-ethylacrylate-copolymer) | water dispersible at pH 2–3 |
| Hydroxypropyl-beta-cyclodextrin | water-insoluble, increases bioavailability |
| Hydroxypropylmethylcellulose (HPMC) | water-soluble, non-ionic |
| KIucel (Hydroxypropyl cellulose) | water-soluble, non-ionic |
| Macrogol | water-soluble |
| Methyl cellulose | water-soluble |
| Poloxamer (polyethylenepolypropylene glycol) | thermoreversible |
| Plastoid (Butyl methacrylate-methylmethacrylate copolymer) | water-insoluble |
| Polydimethylsiloxane (PDMS) | water-insoluble, non-toxic |
| Polyvinyl alcohol (PVA) | water-soluble, adhesive, non-toxic |
| Polyvinyl pyrrolidine (PVP) | water-soluble, adhesive, increase bioavailability |
| Quaternary polymethacrylat (QPM) | water-insoluble |
| Sepineo P600 (acrylamide/sodium acryloldimethyltaurate) | water-insoluble |
| Silicone | water-soluble, non-occlusive |
Conclusions and Further Prospects
According to previous research findings, film-forming systems have proven to be suitable for use as a delivery form due to their high substantivity and cosmetic attractiveness. Drugs can penetrate from the systems into the skin, which enables dermal and transdermal drug application. The formulations also serve as a depot, which enables a sustained release. While the use of film-forming sprays in the field of wound care is already established and well accepted by patients, film-forming systems are still the exception in the treatment of diseases.
In the field of transdermal application, there is, with the testosterone spray Axiron®, already one formulation on the market. For transdermal use, film-forming systems have not yet been able to establish themselves as a therapeutic option against other transdermal systems such as patches. For dermal application, only film-forming solutions for the treatment of topical infections, such as the terbinafine Lamisil Once® spray, have made it to the market; while studies on the treatment of chronic skin diseases were carried out, but no formulation is yet available for patients, neither for daily therapy in the form of cortisone preparations, nor as NSAIDs for acute therapy. The development of therapies for chronic inflammatory skin diseases and topical infections with film-forming formulations could be pursued more vigorously in the future.
Film-forming solutions that are sprayed directly onto the skin create the sensation of a second skin, unlike patch-no-patch systems. On the other hand, precise application and dosing are easier to implement by using patch-no-patch, which are also able to protect the treated skin area and show increased physicochemical stability. Film-forming emulsions also contain a lipophilic phase and can therefore also be used on dry skin areas. Due to their semi-solid character, gels have an advantage in that that they are easier and more precise to apply. All systems are well suited for personalised therapy. The semi-solid and liquid preparations can be produced in individual concentrations and the films can be printed individually.
Furthermore, there are comparatively few developments of film-forming formulations of drugs with hydrophilic character. A focus on the development of such formulations could provide access to further treatment fields.
The formulations can reach out more to the optimal condition of a second skin by optimising the concentration of the individual components and using new ingredients, thus increasing patient compliance. In this context, gels and emulsions can also become more important than the film-forming sprays that have been predominantly established to date, as they are easier to apply.
Another future field of research is the development of lipophilic film-forming systems with oil-soluble film-forming agents. These formulations could be used for chronic inflammatory skin diseases and, in addition to retarded release of the active ingredient and high substantivity, have positive effects on skin properties. This would allow daily therapy with drugs such as cortisone derivatives to be combined with basic or maintenance therapy.