Sodium nitroprusside iontophoresis on the finger pad does not consistently increase skin blood flow in healthy controls and patients with systemic sclerosis

Trials and tribulations of skin iontophoresis in therapeutics

Iontophoresis is a method of non-invasive transdermal drug delivery based on the transfer of charged molecules using a low-intensity electric current. Both local and systemic administration are possible; however, the skin pharmacokinetics of iontophoretically delivered drugs is complex and difficult to anticipate. The unquestionable theoretical advantages of the technique make it attractive in several potential applications. After a brief review of the factors influencing iontophoresis, we detail the current applications of iontophoresis in therapeutics and the main potential applications under investigation, including systemic and topical drugs and focusing on the treatment of scleroderma-related ulcerations. Finally, we address the issue of safety, which could be a limitation to the routine clinical use of iontophoresis.

Scleroderma and evidence based non-pharmaceutical treatment modalities for digital ulcers: a systematic review

OBJECTIVE

Digital ulcers are difficult to heal, increasing the chance of infection, gangrene, amputation and limited functional use of hands. They are a complication in scleroderma or systematic sclerosis (SSc) and occur in approximately 50% of patients. This is a systematic review of the evidence supporting the use of non-pharmaceutical therapeutic modalities and their effectiveness to facilitate the healing of chronic digital ulcers in patients with scleroderma.

METHOD

A comprehensive review of computerised databases from 2000-2013: PubMed/MEDLINE, CINAHL, Pedro, OT Seeker, OT Search, OVID, and Proquest as well as manual review of other resources was completed using the following search terms scleroderma or systemic sclerosis and/or digital ulcers, specific modalities (low level laser therapy, electrical stimulation, intermittent compression, ultrasound, vitamin E, myofascial release, wound dressings, iontophoresis, negative pressure therapy, and exercise), chronic wounds, and wound care. English language studies, from 2000 to January 2013, which used therapeutic modalities to facilitate healing of digital ulcers and use healing of the digital ulcer as an outcome measure were reviewed.

RESULTS

Of the 403 identified articles, only 11 studies addressed non-pharmaceutical treatment modalities to facilitate healing for digital ulcers. Exercise had no direct effect on healing ulcers. The following studies were positive but have limitations in design and sample size:: hyperbaric oxygen therapy (n=2), negative pressure therapy (n=1), intermittent compression (n=27) and acoustic pressure wound healing (n=1). Vitamin E gel showed a significant difference compared to a control group (n=27). Iontophoresis studies have shown that the modality increases blood flow but the results in five different studies are mixed and the application and intensity were inconsistent.

CONCLUSION

No one modality was proven to be the most effective. Larger efficacy studies on treating digital ulcers are needed in order to develop appropriate care guidelines to improve outcomes, promote function and lower health-care costs.

[Assessment of endothelial function in autoimmune diseases]

Numerous autoimmune-inflammatory rheumatic diseases have been associated with accelerated atherosclerosis or other types of vasculopathy leading to an increase in cardiovascular disease incidence. In addition to traditional cardiovascular risk factors, endothelial dysfunction is an important early event in the pathogenesis of atherosclerosis, contributing to plaque initiation and progression. Endothelial dysfunction is characterized by a shift of the actions of the endothelium toward reduced vasodilation, a proinflammatory and a proadhesive state, and prothrombic properties. Therefore, assessment of endothelial dysfunction targets this vascular phenotype using several biological markers as indicators of endothelial dysfunction. Measurements of soluble adhesion molecules (ICAM-1, VCAM-1, E-selectin), pro-thrombotic factors (thrombomodulin, von Willebrand factor, plasminogen activator inhibitor-1) and inflammatory cytokines are most often performed. Regarding the functional assessment of the endothelium, the flow-mediated dilatation of conduit arteries is a non-invasive method widely used in pathophysiological and interventional studies. In this review, we will briefly review the most relevant information upon endothelial dysfunction mechanisms and explorations. We will summarize the similarities and differences in the biological and functional assessments of the endothelium in different autoimmune diseases.

Cathodal iontophoresis of treprostinil and iloprost induces a sustained increase in cutaneous flux in rats

BACKGROUND AND PURPOSE

The treatment of scleroderma-related digital ulcers is still a therapeutic challenge. The most effective drugs are prostacyclin analogues. However, their usage is limited to an intravenous route of administration and by their frequent side effects. The objective of this study was to test whether treprostinil, iloprost and epoprostenol can induce sustained vasodilatation in rats when delivered locally using cutaneous iontophoresis.

EXPERIMENTAL APPROACH

Treprostinil, iloprost and epoprostenol were delivered by cathodal and anodal iontophoresis onto the hindquarters of anaesthesized rats (n= 8 for each group). Skin blood flow was quantified using laser Doppler imaging and cutaneous tolerance was assessed from day 0 to day 3.

KEY RESULTS

Cathodal but not anodal iontophoresis of treprostinil (6.4 mM), iloprost (0.2 mM) and epoprostenol (1.4 mM) induced a significant and sustained increase in cutaneous blood flow. The effects of treprostinil and iloprost were significantly different from those of treprostinil vehicle. Only weak effects were observed when both drugs were applied locally without current. Skin resistance was unchanged in areas treated with prostacyclin analogues. Finally, skin tolerance was good, with no evidence of epidermal damage.

CONCLUSIONS AND IMPLICATIONS

Cathodal iontophoresis of treprostinil and iloprost increases cutaneous blood flow with a good local tolerance. The effects of cathodal iontophoresis of these drugs should be investigated in humans, as they could have potential as new local therapies for digital ulcers in patients with scleroderma.

Oral sildenafil increases skin hyperaemia induced by iontophoresis of sodium nitroprusside in healthy volunteers

BACKGROUND AND PURPOSE

Sildenafil, a specific inhibitor of phosphodiesterase 5A (PDE5A), is currently tested as a treatment for severe Raynaud's phenomenon. Here, we tested whether sildenafil, alone or combined with local sodium nitroprusside (SNP) delivered through skin iontophoresis, increased forearm cutaneous blood conductance in healthy volunteers, and to assess how well this combination was tolerated.

EXPERIMENTAL APPROACH

Ten healthy volunteers were enrolled. Variations in cutaneous vascular conductance (CVC) following oral administration of 50 or 100 mg of sildenafil with or without SNP iontophoresis were expressed as a percentage of maximal CVC, and were monitored using laser Doppler imaging. SNP iontophoresis was performed on the ventral surface of the forearm, 1 h after application of lidocaine/prilocaine cream.

KEY RESULTS

Sildenafil at 100 mg, but not 50 mg, increased overall responses (area under the curve) (44%) and peak responses (29%) to SNP iontophoresis. Sildenafil at 100 mg, but not 50 mg, increased baseline CVC (75%). Incidence of headache was not changed when SNP iontophoresis was combined with sildenafil. One episode of symptomatic arterial hypotension occurred in a volunteer given 50 mg sildenafil, 30 min after the beginning of SNP iontophoresis.

CONCLUSIONS AND IMPLICATIONS

Oral sildenafil at 100 mg potentiated local skin hyperaemia induced by SNP iontophoresis, with no increased incidence of headaches. The combination of oral specific PDE5A inhibitor and nitrates administered through skin iontophoresis deserves further investigation in diseases such as severe Raynaud's phenomenon, with particular attention to the incidence of arterial hypotension.