Preparation, optimisation and characterisation of novel wound healing film dressings loaded with streptomycin and diclofenac

Streptomycin (STP) and diclofenac (DLF) loaded film dressings were prepared by blending Polyox® (POL) with four hydrophilic polymers [hydroxypropylmethylcellulose (HPMC), carrageenan (CAR), sodium alginate (SA) or chitosan (CS)] using glycerol (GLY) as plasticiser. The films were characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, texture analysis (tensile and swelling characteristics) and in vitro dissolution profiles using Franz diffusion cell. SEM showed homogeneous morphology for both blank (BLK) and drug loaded (DL) films. Films prepared by blending of POL with the other polymers showed a reduction in the crystallisation of POL in descending order of SA > CS > HPMC > CAR respectively. DSC and XRD showed no crystalline peaks of STP and DLF suggesting molecular dispersion of both drugs as well as possible drug interaction with negatively charged sulphate ions present in CAR. The DL films did not show any IR bands of both drugs, confirming the DSC and XRD results. POL-CAR-BLK films showed higher tensile strength (12.32 ± 1.40 MPa) than the POL-CAR-DL films (9.52 ± 1.12 MPa). DL films plasticised with 25% w/w GLY revealed soft and tough (tensile strength 1.02 ± 0.28 MPa, % elongation 1031.33 ± 16.23) formulations. The swelling capacities of POL-CAR-BLK and POL-CAR-DL films were (733.17 ± 25.78%) and (646.39 ± 40.39%), increasing to (1072.71 ± 80.30%) and (1051 ± 86.68%) for POL-CAR-BLK-25% GLY and POL-CAR-DL-25% GLY respectively. POL-CAR-DL films showed significantly (n = 3, p < 0.0318) lower cumulative release of STP and DLF (52.11 ± 1.34, 55.26 ± 2.25) compared to POL-CAR-DL-25% GLY films (60.07 ± 1.56, 63.39 ± 1.92) respectively.