Efficacy of ultrasound mediated microbubbles in diclofenac gel to enhance transdermal permeation in rheumatoid arthritis induced rat

In previous study in the literature, the effect of ultrasound on the transdermal permeation of the nonsteroidal anti-inflammatory drug, diclofenac has been investigated. Therapeutic ultrasound can increase circulation in the inflamed joint and decrease arthritic pain. Recently, transdermal drug delivery has been demonstrated by ultrasound (US) combining with microbubbles (MBs) contrast agent. In this study, the efficiency of US-MBs mediated diclofenac delivery for adjuvant-induced rheumatoid arthritis (RA) in rats was evaluated. RA was induced by injection of 100 μl Freund's complete adjuvant into the ankle joint in SD male rats (250-300g) and were randomly divided into five groups: (1) control group (C); (2) penetrating diclofenac alone (D); (3) US alone (U); (4) US combined with penetrating diclofenac (DU); (5) US combined with MBs and penetrating diclofenac (DUB). The evaluations of ankle width were performed for 10 days by high frequency (40MHz) US B-mode and color Doppler mode imaging before and after treatment. Longitudinal US images of arthritis induced show synovitis and neovascularity. After treatment, only a little neovascularity has been observed. The recovery rate at 10th day in the group DUB (97.7±2.7 %) was significantly higher than in the group C (1.0±2.7 %), group D (37.5±4.6 %), group U (75.5±4.2 %) and group DU (87.3±5.2 %) (p <; 0.05). Our results investigated that the treatments of US and MBs can increase skin permeability to enhance diclofenac sodium delivery and inhibit inflammation of the tissues surrounded the arthritic ankle. In color Doppler imaging, after the combination treatment, the synovial neoangiogenesis in the arthritic area was reduced quickly.