Development of products for controlled releasing topical and transdermal drugs using nano/micro-encapsulation and microneedles (Presentation)

Student: Raha Rahbari
Company: P & S Nano Ltd
Academic Supervisor: Dr Zhidao Xia & Dr Owen Guy

Drug-loaded Microspheres in Conjugation with Hydrogel Patches for Treatment of Psoriasis

Drug delivery refers to the method, formulation and technology for carrying a pharmaceutical compound to a specific site of action in the body. The current purpose of drug delivery is to develop a targeted delivery in which the drug is only active in a specific area of the body and perhaps, under specific conditions. This system has to maintain rate of release, ensuring the drug is released in a controlled manner over a period of time.

Poly lactic-co-glycolic acid (PLGA) and polycaprolactone (PCL) are the most attractive polymeric used to fabricate devices for drug delivery applications. PLGA and PCL are FDA approved polymers in which exhibits a wide range of erosion times. They are biocompatible and biodegradable polymers, which has tunable mechanical properties. In particular, PLGA and PCL have been widely studied for design and development of different types of devices for controlled delivery of molecules, proteins and drugs in commercial use and in research.

This research project aimed to design a controlled release drug delivery PLGA and PCL microspheres in conjugation with hydrogel patches. It is believed that development of such a novel drug delivery system would be use for treatments of many dermatological conditions such as Psoriasis and Eczema. Some of the advantages of using drug-loaded microspheres in conjugation with hydrogel patches include:

  • There is a consistent dose per cm2 given by a topical patch application.
  • By cutting the patch to particular shape of patient’s skin problem, the dose is only applied to the site of the skin problem – rather than the healthy surrounding area – thereby lessening any possible adverse events on the adjacent area.
  • The dose can conveniently be applied for a longer period – once or twice per day – with a patch, especially compared to several applications per day of creams and gels. The hydrogel patch technology is also considerably less “messy” than conventional creams, gels or ointments in the topical application process.
  • These patch types have a gentle adhesion which is especially important for dermatological conditions – where the skin is usually already damaged or liable to damage, inflammation, or loss of skin integrity. These patches will stretch and conform to skin as it moves, therefore lessening any possible mechanical damage compared to less flexible patch technology.
  • The hydrogel patches can be safely and easily removed if the API causes any skin adverse events.

Biodegradable PLGA and PCL microspheres fabricated using emulsification solvent evaporation technique. Dithranol drug was candidate to encapsulate within the spheres. The results demonstrated 99% encapsulation of Dithranol inside the PLGA microspheres. The PLGA microspheres with average size distribution of 70um provided 28% in vitro release of Dithranol in 24h. The viability assays and toxicology study of the microspheres represented that these carriers are safe and capable to use for human treatment applications.

The technology developed here suggested that the approach of using drug-loaded particles in conjugation with hydrogel patch, as delivery vehicles, is feasible and it created new opportunity to customise the release of pharmaceutical and active ingredients.