Polyurethane-based drug delivery systems

Synthesis and structure-property relationships of biodegradable polyurethanes

“…The release of drugs from polymeric systems refers to a process in which drugs migrate from their initial position inside a polymer matrix to the release medium. Alternatively, drug molecules which are initially adsorbed onto a material surface might be released once brought into contact with an external medium [177]. However, it should be noted that the incorporation of drugs into polymeric systems, especially at high drug concentrations, cannot only affect the polymer properties of the systems, but also influence the release mechanisms and therapeutic efficiency of the drug.…”

“…hydroxyl or amine) with isocyanate, obtaining in that way drug incorporated into the polymer backbone [196] or dispersed in PU matrices [197]. Covalently bound drugs are released from the polymer via passive hydrolysis of urethane and urea bonds following their degradation rate [196], while the release of dispersed drugs depends on drug loading, the solubility of the drug in the matrix and intermolecular interactions between them, as well as on the swelling properties of the polymer [177]. PUbased systems have to date been evaluated for delivery of various pharmaceutical agents such as antibiotics [198], non-steroid antiinflammatory drugs [199], anticancer drugs [200], growth factors, etc.…”

Actividad antibacteriana, degradación hidrolítica y microbiana y citotoxicidad in vitro de poliuretanos sintetizados con polioles derivados del aceite de higuerilla

“…Los enlaces uretanos son similares a las amidas y pueden ser hidrolizables por enzimas presentes en las bacterias empleadas para el ensayo. 41,42 Esto coincide con lo expuesto por Gogoi 40 donde se describe que la presencia de enlaces amida y urea presentes en la estructura ramificada del polímero facilita la degradación. Según Cherng la degradación de los PUs es debida a la ruptura de enlaces hidrolíticamente débiles característicos de los segmentos suaves y por lo tanto concluyen que la velocidad de degradación in vitro depende principalmente del tipo de poliol utilizado en la síntesis por el tipo de enlaces éster que se encuentran en la estructura.…”

“…Según Cherng la degradación de los PUs es debida a la ruptura de enlaces hidrolíticamente débiles característicos de los segmentos suaves y por lo tanto concluyen que la velocidad de degradación in vitro depende principalmente del tipo de poliol utilizado en la síntesis por el tipo de enlaces éster que se encuentran en la estructura. 41 …”

Development and in vitro evaluation of polyurethane microparticles as carrier for bevacizumab: an alternative treatment for retinopathy of prematurity

“…Initially, the polyurethanes were developed in Europe as flexible fibers and foams (Shelke et al, 2014), and in the last 40 years, they have also been used in biomedical appliances or devices due to their biocompatibility and their mechanical flexibility (Cherng et al, 2013). The enormous increase of researchers' interest for polyurethane materials is due to the following reasons: (i) the rigidity of the material can be easily adjusted by modifying the order of magnitude of the molecular weight of polyols used in the synthesis (Król, 2007); (ii) the size of macromolecular structures can be easily adjusted by modifying the quantity of chain extenders which are used in the synthesis (diols with low molecular weight, as mono-ethylene glycol, 1,4-butanediol, 1,6-hexanediol) (Ho et al, 1999); (iii) the stability or degradation of polyurethane materials in aqueous media can be changed by adjusting the ratio of polyester / polyether used as raw materials (UrgunDemirtas et al, 2007).…”