Cutaneous Iontophoresis of Treprostinil in Systemic Sclerosis: A Proof-of-Concept Study

Iontophoresis of treprostinil promotes wound healing in a murine model of scleroderma-related ulcers

OBJECTIVE

Systemic Sclerosis (SSc) is a rare, chronic disease characterized by fibrosis, vascular alterations and digital ulcerations. Few drugs have shown efficacy to enhance wound healing of existing SSc-related ulcers. Local delivery of treprostinil, a prostacyclin analogue, may improve wound healing. The present work aimed first at developing a mouse model of SSc-related ulcerations and second at assessing the effect of iontophoresis of treprostinil on wound healing.

METHODS

We used two murine models of SSc: chemically-induced with HOCl, and Urokinase-type plasminogen activator receptor (uPAR)-deficient. Excisional wounding was performed on the dorsal midline with a biopsy punch. Animals were randomized into three groups: treated with electrostimulation alone, with treprostinil iontophoresis, or untreated. We assessed wound healing over time, as well as skin microvascular reactivity, inflammation, microvessel density, and collagen distribution, before wounding and after re-epithelialization.

RESULTS

uPAR-/- mice, but not HOCl-treated mice, showed impaired wound healing and decreased microvascular reactivity compared with their controls. Treprostinil iontophoresis improved wound healing and microvascular density and decreased inflammation in uPAR-/- mice, while electro-stimulation did not. However, treprostinil had no effect on microvascular reactivity and collagen distribution.

CONCLUSION

This study suggests that excisional wounds in uPAR-/- mice are a relevant model of SSc-related ulcers. In addition, treprostinil iontophoresis enhances wound healing in this model. Further work in now needed to show whether this effect translates in humans.

The complementary effects of galvanic current electrical stimulation associated with conservative treatment to increase vasodilation in patients with Raynaud's phenomenon: a randomized trial

OBJECTIVE

To analyze the effectiveness of an electrotherapy intervention with galvanic current on symptoms associated with Raynaud's phenomenon.

DESIGN

Single-blind randomized controlled trial, parallel design (1:1 ratio) and intention-to-treat analysis.

SETTING

Virgen de las Nieves Hospital, Granada, Spain.

SUBJECTS

Thirty-four participants with Raynaud's phenomenon, with a mean (SD) age of 43.43 (17.62) years.

INTERVENTIONS

The patients were randomly assigned to a control group with conservative treatment (anti-inflammatory, vasodilatory and analgesic drugs) or an intervention group that received conservative treatment and vasodilatory electrical stimulation during seven weeks, three times/week for a total of 20 sessions.

MAIN MEASURES

The primary outcome was the number of attacks. Secondary outcomes were pain, peripheral blow flow, oxygen saturation, upper limb disability, central sensitization, pain catastrophizing and temperature recovery. All outcomes were assessed at baseline, posttreatment and at two months of follow-up.

RESULTS

The galvanic current electrotherapy group showed significantly greater improvements in the number of attacks (mean difference = 26.3, 95% confidence interval (CI) = 14.4 to 38.3), pre-cold stress pain (95% CI = 0.6 to 2.4), radial artery blood flow (95% CI = -7.8 ⩾ x ⩽ 1.3), ulnar artery blood flow (95% CI = -8.63 to 0.60), oxygen saturation (95% CI = -1.7 ⩾ x ⩽ -0.29), upper limb disability (95% CI = 1.1 to 22.3), central sensitization (95% CI = 6.7 to 18.2) and temperature recovery (95% CI = -5.7 ⩾ x ⩽ -0.32) than the conservative treatment group.

CONCLUSION

This study suggests that a complementary treatment with galvanic current in combination to conservative approach is superior to conservative applied as isolate, in reducing the clinical manifestations and disability in Raynaud's phenomenon.

Treprostinil Hydrogel Iontophoresis in Systemic Sclerosis-Related Digital Skin Ulcers: A Safety Study

Digital skin ulcers are a severe complication of systemic sclerosis. The first-line treatment is intravenous iloprost, but it induces dose-limiting adverse effects. Local administration of treprostinil through skin iontophoresis may be a safe alternative. We conducted a 2-stage, randomized, placebo-controlled single-ascending-dose study in healthy volunteers and patients with systemic sclerosis-related digital ulcer. We further explored the effect of the procedure on skin blood flux. In a first group of healthy subjects, treprostinil and placebo iontophoresis were performed at 3 locations (ie, 6 skin sites): the sole of the foot, the leg, and the fingers. We used a 1-mg/mL hydrogel of treprostinil. We then randomly treated systemic sclerosis-related digital ulcers in a 3:1 ratio of treprostinil or placebo. We used concentrations from 0.1 to 1 mg/mL. All adverse events were recorded and rated according to the Common Terminology Criteria for Adverse Events (CTCAE), whereas skin microvascular blood flux was recorded with laser speckle contrast imaging. Among the 12 healthy volunteers, we observed 60 local adverse effects: burns, skin pain, erythema, and pruritus, graded 1 or 2 on the 5-point CTCAE scale. Treprostinil iontophoresis significantly increased skin blood flux on the leg (AUC_0-4 h at 88 460% ± 6436% versus 12 730% ± 3397% baseline flux.min respectively; P < .001) and on the sole of the foot (AUC_{0-3 h} at 20 124% ± 6119% versus 3142% ± 3036% baseline flux.min, respectively; P = .018) with a trend on the finger. Among 5 patients with systemic sclerosis-related digital ulcer, 2 resolutive local adverse effects were reported. Iontophoresis of treprostinil hydrogel was safe in systemic sclerosis patients with digital ulcer.

Evidence-based management of Raynaud's phenomenon

Raynaud's phenomenon (RP) is relevant to the rheumatologist because it may signify an underlying connective tissue disease and also because it can be very challenging to treat, especially when it has progressed to digital ulceration or critical ischaemia. This review article discusses diagnosis (does this patient have an underlying connective tissue disease?), including the role for nailfold capillaroscopy, and treatment. Management of 'uncomplicated' RP is first described and then treatment of RP complicated by progression to digital ulceration or critical ischaemia, highlighting recent advances (including phosphodiesterase type 5 inhibition, and endothelin 1 receptor antagonism) and the evidence base underpinning these. Possible future therapies are briefly discussed.

Therapeutic implications from the pathogenesis of Raynaud's phenomenon

INTRODUCTION

Raynaud's phenomenon (RP) can be either primary (idiopathic) or secondary to a number of different diseases/conditions, when vasopasm can be superimposed upon structural vascular abnormality or a hyperviscosity state and may then lead to severe ischaemia with tissue damage. Treatment must be tailored to the individual. Areas covered: This review discusses how increased understanding of the pathogenesis of RP has driven and is driving new approaches to therapy, and how we are now better able to predict which patients presenting with RP are likely to have an underlying disease requiring specific intervention. Medline searches (1946 to August 2016) were conducted for 'Raynaud's' in combination with relevant terms including different drugs. All papers identified were English language, with abstracts. Expert commentary: Randomised controlled trials of RP present particular challenges. The major aim must continue to be development of safe, effective treatments for patients across the spectrum of RP.

Treprostinil Iontophoresis Improves Digital Blood Flow during Local Cooling in Systemic Sclerosis

INTRODUCTION

Severe Raynaud's syndrome and DUs are the most prevalent manifestations of SSc peripheral microvascular disease. We tested whether treprostinil iontophoresis on the finger pad of patients with SSc would improve digital blood flow during hand cooling.

METHODS

Eleven patients with limited cutaneous SSc underwent a double-blinded iontophoresis of treprostinil (2.56 × 10(-4) M during two hours) and placebo (NaCl 0.9%) on two finger pads. Then, the hand was inserted for 30 minutes in a fenestrated cooling box at 8 °C, and skin blood flow was recorded continuously using LSCI.

RESULTS

During the local cooling, CVC was significantly higher at the treprostinil site than at the placebo site and remained higher 30 minutes after the test.

CONCLUSIONS

In patients with SSc, digital treprostinil iontophoresis shifts skin blood flow upward during local cooling of the hand and during the initial rewarming phase. Digital treprostinil iontophoresis should now be tested in larger scale studies.

Digital ulcers in systemic sclerosis

Digital ulcers (DUs) are a common visible manifestation of the progressive vascular disease that characterizes the SSc disease process. DUs not only impact significantly on patients' quality of life and hand function, but are also a biomarker of internal organ involvement and of disease severity. The aetiology of (digital) vascular disease in SSc is multifactorial, and many of these factors are potentially amenable to therapeutic intervention. The management of DU disease in SSc is multifaceted. Patient education and non-pharmacological interventions (e.g. smoking cessation) should not be neglected. There are a number of drug therapies available to prevent (e.g. phosphodiesterase type-5 inhibitors and ET receptor-1 antagonists) and treat (e.g. i.v. iloprost) DUs. DUs are also important for two other reasons: firstly, as a primary end point in SSc-related clinical trials; and secondly, DUs are included in the ACR/EULAR SSc classification criteria. However, the reliability of rheumatologists to grade DUs is poor to moderate at best, and this poses challenges in both clinical practice and research. The purpose of this review is to provide the reader with a description of the spectrum of DU disease in SSc including pathophysiology, epidemiology and clinical burden, all of which inform the multifaceted approach to management.

Transdermal Drug Delivery: Innovative Pharmaceutical Developments Based on Disruption of the Barrier Properties of the stratum corneum

The skin offers an accessible and convenient site for the administration of medications. To this end, the field of transdermal drug delivery, aimed at developing safe and efficacious means of delivering medications across the skin, has in the past and continues to garner much time and investment with the continuous advancement of new and innovative approaches. This review details the progress and current status of the transdermal drug delivery field and describes numerous pharmaceutical developments which have been employed to overcome limitations associated with skin delivery systems. Advantages and disadvantages of the various approaches are detailed, commercially marketed products are highlighted and particular attention is paid to the emerging field of microneedle technologies.

Effect of continuous vs pulsed iontophoresis of treprostinil on skin blood flow

INTRODUCTION

Systemic sclerosis (SSc) is a rare disease affecting digital microcirculation, leading to finger ulcers and in some cases to amputation. Prostacyclin analogues can be used intravenously but their therapeutic effect is counterbalanced by potentially serious vasodilatation-induced side effects. Iontophoresis of treprostinil could be a promising local therapeutic alternative for SSc-related digital ulcers. Iontophoretic drug delivery is complex, and whether continuous or periodic current should be used remains debated. The objective of the present work is to compare the effect of continuous vs pulsed iontophoresis of treprostinil in rats.

MATERIALS AND METHODS

Treprostinil (0.64 mM and 0.064 mM) and NaCl were delivered by cathodal iontophoresis onto the hindquarters of anaesthetized rats. Three protocols delivering the same quantity of current were compared: one was continuous (100 μA during 20 min) and two were periodic (B: twenty 1-min cycles with 200 μA during 30 s followed by 30 s Off; and C: twenty 1-min cycles with 600 μA during 10s followed by 50s Off) (n=8 for each protocol with each concentration). Skin blood flow was quantified using laser Doppler imaging and skin resistance was calculated with Ohm's law.

RESULTS

All protocols induced a significant increase in skin blood flow. At the lower concentration (0.064 mM treprostinil) the pulsed 10/50 sequence significantly enhanced cutaneous blood flow (Table 1; Fig. 1B) compared to continuous iontophoresis or the 30/30 sequence. We noted that the pulsed iontophoresis of NaCl (10/50 sequence) induced a significant early increase in cutaneous blood flow in comparison with continuous iontophoresis. Skin resistance measures were negatively correlated with current intensity delivered.

CONCLUSION

In conclusion, pulsed iontophoresis of treprostinil with a 10 s/50 s (On/Off) protocol at 600 μA increases the efficacy of iontophoresis at 0.064 mM but not at a tenfold higher concentration. Pulsed iontophoresis could be used to optimize treprostinil iontophoresis, to provide similar efficacy with decreased costs, and should now be tested on humans.