Effects of drug chemistry on the dispersion and release behaviour of polyurethane organosilicate nanocomposites

There are a range of factors proposed to perturb the release mechanisms in polymer nanocomposites (NCs) but little focus has been directed towards the understanding of interactions between the drug and NC which can also affect the drug release behaviour. A variety of model/active drugs of different size, surface charge and polarity were investigated for their impact on silicate dispersion and drug release of polyurethane nanocomposites (PUNC) composed of three components. Findings revealed that the addition of a fourth component, i.e. a drug, can disrupt the dispersion of silicates and the disruption is dependent on the strength of electrostatic interactions and hydrogen bonding with the silicates. As a result, the release rate and level of retardation were governed largely by the physical and chemical properties of the drug. Furthermore, due to these interactions, release of hydrophilic drugs is not necessarily at a higher rate than for hydrophobic drugs but is dependent on the host polymer interaction.