Testing the physical properties of drug delivery films
2 minute read
Thin films have recently been attracting attention in drug delivery due to their capacity to safely load medications and release them in a regulated manner, improving drug efficacy. They are more patient compliant and an alternative to oral drug delivery employing self-application and prolonged action.
The development of thin films comprises of various considerations regarding anatomical and physiological constraints, physicochemical properties and types of drug substance and use of various polymers (matrix, hydrophilic and hydrophobic) as well as the characterisation methods.
Various scientists are working on the formulation and development of thin films as a novel drug delivery system. The publication Thin Films: A Promising Approach for Drug Delivery Systems is an excellent background document covering all of these aspects and discusses measurements of elongation, tensile strength, tear resistance, Young’s modulus and folding endurance. These properties are typically tested with a Texture Analyser by supporting the films in tensile grips and performing either a tensile test or a cycling compression test. The above images show a tensile test and folding endurance test using Tensile Grips.
Recent academic published work assessing drug delivery films in this way:
Oromucosal Alginate Films with Zein Nanoparticles as a Novel Delivery System for Digoxin
A biaxial extension approach is also recommended to measure the tensile properties of films. The film sample is supported between plates which expose a circular section of the sample allowing a spherical probe to be pushed through to perform extension and elasticity measurements. During a test, the maximum force to rupture the sample (burst strength) is recorded. The additional measurements of resilience and relaxation of a wide range of food products broadens the application of this rig, which can also assess mechanical properties of sheet packaging materials.
See a wide range of physical testing methods using the Texture Analyser for films
