Diltiazem Gel Versus Nitroglycerin Ointment in Healing Process of Scleroderma Digital Ulcers

Introduction:

Systemic sclerosis, also named scleroderma (SSc), is an autoimmune connective tissue disease associated with small vessels vasculopathy and collagen deposition in skin and other internal organs [1, 2]. About 30-60 % of patients with limited and diffused type of scleroderma developed by digital ulcers (DUs) in course of their disease [3]. Depending on the sites of the ulcers, their pathophysiology is differed. The ones on distal parts of the digits are related to ischemic changes based on Raynaud phenomenon, intimal fibroproliferation, and thrombosis; while, the ones on bony prominences are mostly due to microtrauma and following poor vascularization for its healing [4].

These ulcers can affect the quality of life of the patients mostly due to the pain and difficulty in their healing [3]. Accordingly, several therapies have been introduced for improving its healing process. Among them, nitroglycerin ointment was assessed to be an effective topical agent on Raynaud phenomenon; however, there can be found only one study assessing its effect on SSc digital ulcer, which was shown to be non significant [5-7].

Calcium channel blockers (CCB) such as diltiazem are also being used for Raynaud phenomenon in scleroderma patients. Yet, some of their potential side effects such as peripheral edema, hypotension, and headache limit the up titration of these classes of drugs [8]. Moreover, their therapeutic effects on SSc digital ulcers are still being questionable. Only, one clinical trial assessed the effect of nifedipine on ulcer healing, which resulted in non-significant difference compared with placebo[7].

In addition to systemic form of CCBs, topical form of them such as diltiazem gel is also being available. Previous studies introduced this form of diltiazem as a vasodilator, mostly, for treatment of chronic anal fissure [9]. Comparing its effects with topical nitrate for chronic anal fissures showed some controversies. Some studies resulted in no significant difference between them; yet, the study by Ala et al, demonstrated that diltiazem gel has superiority to nitroglycerin ointment [10, 11]. Another survey, in spite of finding non- significant difference between these two agents in treatment of anal fissure, gave priority to diltiazem gel because of headache induced by nitroglycerin ointment [12].

As it can be inferred from previous studies, most of the medications used for scleroderma DU healing are drugs applied for Raynaud phenomenon. In spite of the determined therapeutic effects of such drugs on this phenomenon, their efficacy on healing of DUs is still being obscured. Furthermore, because of the complications of systemic therapies and limitation in their dose up titrating, topical agents are being preferred. However, there has not still found an effective topical therapy for DU of scleroderma patients.

The effect of topical diltiazem as a vasodilator agent in treatment of anal fissure brings to mind this idea that it may be also effective in healing of scleroderma DUs. In addition, comparing the effect of diltiazem gel and topical nitrate in anal fissures, generally, suggest the preference of the former. However, there can not be found any survey comparing the effects of these two topical vasodilators in treatment of DU. Thus, in this study, we aim to assess the effect of topical diltiazem on SSc digital ulcers and compare it by topical nitroglycerin.

Material and Method:

A single blind case control study will be done on 90 scleroderma patients registered in Tertiary Centers of rheumatology diseases of Shiraz University of Medical Sciences, Shiraz, Iran. (The sample size was estimated using the formula of n = (Zα/2+Zβ)2 * (p1(1-p1)+p2(1-p2)) / (p1-p2)2 [ Zα/2 is the critical value of the Normal distribution at α/2 (for a confidence level of 95%, α is 0.05 and the critical value is 1.96), Zβ is the critical value of the Normal distribution at β (for a power of 80%, β is 0.2 and the critical value is 0.84) and p1 and p2 are the expected sample proportions of the two groups]).

Inclusion Criteria:

The patients' scleroderma was diagnosed based on criteria of LeRoy[13]. The ones with ages between 20-70 years old will be entered into the study. They, all, should have at least one active digital ulcer.

Exclusion Criteria:

The cases with comorbid diseases such as diabetes, thyroid disease and cardiovascular diseases will be excluded from the survey. Moreover, the patients who are smoker, opium addict or alcohol abuser will also drop out of the study. In addition, the ones who received inhaled or oral prostanoid in last 3 months, phosphodiesterase inhibitors except for intermittent treatment of erectile dysfunction in last 1 month and the ones received antibiotics 2 weeks prior to the study will, also, be excluded. The baseline hepatic function test will be assessed and the cases with moderate to severe hepatic impairment or increase in aminotransferase levels more than 3 will also be excluded from the survey.

The study design:

The patients will be divided into 3 groups; one control group consisting of 30 cases, and two experimental groups with 30 patients in each of them. The control one (C) receiving Vaseline ointment as placebo, the experimental group 1 (E1) which will receive diltiazem gel (2%) applied on DUs two times daily and experimental group 2 (E2) treating by nitroglycerin ointment (2%) applied two times daily for 8 weeks.

The number of the DUs and the mean diameter of all DUs will be measured in 3 groups at the beginning and at the end of the study. Moreover, the site of the ulcers (fingertip, proximal interphalangeal joint (PIP), distal interphalangeal joint (DIP), metacarpophalangeal joint (MCP)) will be also taken into account and be submitted for each patient.

The number of new DUs developing during the study and the difference between mean diameters of them will be compared between 3 groups. In addition, the difference in mean of DUs in different sites will also be compared to see which site has more responsiveness to topical therapeutic agents used in this survey.

Ethical Issues:

Informed consent to the entire protocol as well as forms compatible with Helsinki Declaration was obtained from each patient. Ultimately, the ones who agreed to enroll will be recruited for the study.

Statistical Analysis:

Data will be entered into SPSS 19. For comparing the number and mean difference of digital ulcers' diameters between 3 groups and between different sites of the ulcer, one-way ANOVA will be applied. In addition, Bonferroni test as the post hoc of ANOVA will be applied for pairwise comparison of the groups. The significant p-value in all studies will be considered \<0.05.