BEYOND THE TABLET: ORAL THIN FILMS AS A PLATFORM FOR PATIENT-CENTRIC, 3D-PRINTED DRUG DELIVERY

Oral thin films (OTFs) are flexible drug delivery systems that disintegrate or dissolve quickly in the oral cavity and are convenient to use, without the need for water. The ease of administration and quick onset of drug release, as well as the possibility to enhance patient adherence, has led to growing interest in this new type of dosage form as alternatives to conventional oral dosage forms. This review covers the formulation composition, production methods, assessment criteria and new applications of OTFs. Key formulation excipients like film-forming polymers, plasticisers, sweeteners, flavouring agents, surfactants and permeation enhancers are emphasised. The conventional manufacturing techniques like solvent casting, hot-melt extrusion, rolling, semisolid casting and solid dispersion extrusion as well as the advanced printing technologies like inkjet, flexographic and three-dimensional (3D) printing are reviewed. Other important qualities like thickness of the film, the number of times a film can be folded, the pH value of the surface, the uniformity of the drug, mechanical properties of the film, disintegration and drug release are also discussed. New developments in electrospinning, nanotechnology, multilayer films and customized OTFs illustrate opportunities that may lead to enhanced drug loading, dissolution and therapeutic precision. These improvements, however, have come with their own set of issues, such as a small payload of drugs, moisture sensitivity, stability, scale-up and regulatory standardization. OTFs are an intriguing platform for patient-centred and personalized drug delivery, and additional research is needed to ensure their scale-up and clinical translation.