This is a 2 part study to assess the safety and efficacy of a nitric oxide (NOx) generating dressing on chronic diabetic foot ulcers (DFU). Nitric oxide has a range of effects on the body including vasodilation and angiogenesis. It is also a potent antimicrobial. This 140 patient, randomised, controlled clinical study will assess the ability of a simple 2 part, NOx generating dressing to increase blood flow in DFUs and to improve healing in chronic DFUs compared to standard of care.

This is a clinical study of a new wound dressing for diabetic foot ulcers (DFU). The dressing consists of 2 stable layers that when placed together release Nitric Oxide. In preclinical studies NOx delivery has caused significant vasodilation, angiogenesis and demonstrated potent anti-microbial activity.

In part 1 of the study, the dressing will be applied to up to 20 DFUs for a set period and the blood flow in and around the wound will be measured before and after application of the dressing. Any adverse events will be recorded.

If an increase in blood flow is seen and the dressing is well tolerated, part 2 will begin, which is a multi-centre, 120 patient, randomised, controlled study. 60 patients with chronic DFUs will be treated with the NOx generating dressing and 60 patients will continue to receive standard of care. The efficacy and the tolerability of the dressing will be measured.

The NOx dressing will be changed at least every 2 days and the standard of care changed as in normal clinical practice.

At weekly clinical visits the diameter, area and volume of the wound will be measured. The infective status of the wound will be assessed and the inflammatory profile of the wound will be measured.

Inclusion Criteria:

• Male or female patients aged over 18 years.
• Diagnosed with type 1 or type 2 diabetes.
• With a chronic (present for at least 6 weeks) full-thickness foot ulcer (on or below the malleoli) not penetrating to tendon, periosteum or bone, and with a cross-sectional area between 25 and 2500 mm2.
• Patients must have pedal blood flow between normal and moderately ischaemic. Measurable as a palpable pedal pulse or in the absence of a palpable pedal pulse they must have a TcPO2 of ≥30mmHg or an ABPI of between 0.5-1.00, or > 1.2. (An ABPI of >1.2 is associated with calcification rather than ischaemia. We are including patients with an ABPI >1.2 because ABPI is measured in large arteries. NOx has the ability to dilate medium to small arterioles which are less likely to be calcified.)
• With some degree of neuropathy (as commonly seen in the Diabetes Foot Clinic).
• Able to read and understand the Volunteer Information Sheet and to provide meaningful written informed consent.
• Able and willing to follow the Protocol requirements.

Exclusion Criteria:

• Female patients who are pregnant or breast-feeding
• Any other serious disease likely to compromise the outcome of the trial
• Participation in any clinical study during the eight (8) weeks preceding the dosing period of the study
• Wound area greater than 2500 square mm;
• Patients with severe ischaemia. Measurable as absence of palpable pedal pulse and a TcPO2 of less than 30mmhg, or ABPI < 0.5 or between 1.0-1.2.