Green natural rubber-based membrane for drug release

Abstract

Drug release membranes have been developed in various points of view for many decades. They should be flexible responding to body movement for the patient convenience. Most of them are synthetic materials. Since natural rubber (NR) is elastic and flexible, it is an interesting green material to develop as a drug release membrane. However, there is limitation of drug release of NR membrane. Therefore, the development of drug release efficiency of NR membrane is important and challenging. The objective of this work is to develop drug release membrane from NR based as NR is an alternative green material. NR, epoxidized natural rubber (ENR), poly(vinyl alcohol) (PVA), NR/PVA and ENR/PVA membranes were prepared by casting process. Sodium diclofenac was used as a drug in this work. The result from H1 NMR revealed that 25 mol% ENR was obtained. It was proven that there is no formation of chemical bonding between drug and matrix membrane by Fourier transform infrared spectroscopy characterization. The swelling ratios of PVA, ENR/PVA, NR/PVA were about 165%, 120% and 100%, respectively, whereas ENR and NR were not swollen. It is probably due to the high hydrophilicity of PVA. NR and NR/PVA membrane surfaces presented some agglomeration of drug particles shown in scanning electron microscopy micrographs. The drug distribution in NR matrix was very poor whereas obvious agglomeration in ENR and PVA membranes was not present. The polar groups (epoxide and hydroxyl) may assist in ionic drug distribution. The result of drug release showed that neat NR membrane gave the lowest value at about 50%. Therefore, the drug was predicted to be trapped inside the NR matrix. This was similar to the case of NR/PVA membrane, whereas PVA membrane provided the highest and fastest release compared to others. However, in case of ENR, the %drug release increased gradually with the release time increased until it was constant at 7 hours onwards. It can be said that the modification of NR by adding hydrophilic group (as ENR) could enhance the %drug release. Moreover, the addition of hydrophilic part (combination of PVA) also increased the %drug release that obviously seen in ENR/PVA and NR/PVA membranes.