Efficacy of A Non-Invasive Botulinum Toxin Microneedle Pad for the Treatment of Secondary Raynaud's Phenomenon

Background

Botulinum toxin-A (BTX-A) has demonstrated effectiveness in treating Raynaud's phenomenon in systemic sclerosis (RP-SSc) by improving hand function and condition scores. The current standard of care requires BTX-A to be administered via multiple, painful invasive injections, which carry recognized risks including local infection at injection sites and transient localized intrinsic hand muscle weakness due to toxin diffusion. Microneedles are developed to reduce injection pain and provide a less invasive method than conventional injections. This study evaluates the efficacy and adverse reactions of a BTX-A microneedle pad compared with 2% topical isosorbide dinitrate (ISDN) cream for the treatment of RP-SSc. The microneedles are specifically designed to penetrate the epidermis and reach the dermis layer. This design facilitates localized drug delivery while ensuring the needle tips do not reach blood vessels, preventing the drug from entering systemic circulation. The microneedle array is engineered with an evaluated penetration depth of around 70-80% of its height. The targeted insertion sites for the microneedles are located on the lateral and slightly dorsal aspects of the proximal finger base.

Study Design and Treatment Arms

The trial is a randomized, placebo-controlled, parallel-group study.

Group A (Botox) receives a one-time BTX-A microneedle pad (10 units per pad) applied once on the affected hand plus topical placebo cream applied three times daily.

Group B (Nitrate) receives a placebo microneedle pad (normal saline) applied once plus 2% topical ISDN cream applied three times daily.

Drug Preparation and Administration

The investigational BTX-A product is supplied as a sterile, vacuum-dried powder in a single-use vial containing 100 Units, which is reconstituted with 0.9% sterile, preservative-free sodium chloride to achieve a concentration of 10 units/mL. The medication is divided and administered to both lateral sides of the digits, with 5 units (0.5 mL) administered per side.

The 2% ISDN topical emulsion is compounded by mixing the crushed equivalent of 400 sublingual tablets (5 mg per tablet) with 85 g of a semisolid hydrophilic base. The ISDN preparation is divided into 10 g units and assigned a 6-month expiration date when stored at temperatures between 2 and 8°C.

Study Procedures and Follow-up Schedule

Baseline evaluations include medical history, serological tests, demographic data, vital signs, physical examinations, clinical characteristics of SSc, concomitant medications, and comorbidities. Routine laboratory assessments include complete blood count, erythrocyte sedimentation rate, c-reactive protein, renal function, liver function, urinalysis, creatine kinase, thyroid function test, chest radiography, pulmonary function test, and echocardiography.

Follow-up evaluations occur at Week 1, Week 4, and Week 12 post-treatment to monitor vital signs, physical examinations, clinical characteristics of SSc, routine laboratory assessments, concomitant medications, drug compliance, and complications such as intrinsic hand muscle weakness.

Withdrawal, Rescue Therapy, and Termination CriteriaParticipants will be withdrawn from the study if they develop active systemic infection, localized infection at microneedle pad sites, serious adverse events relating to BTX-A (such as weakened hand grip or paresthesia), severe local allergic reactions, intolerable pain from microneedle application, inability to tolerate wearing the patch until full absorption, worsening Raynaud's phenomenon, new digital ulcers, gangrene, severe headache, need for hospitalization, undergo hand surgery during the study, or self-withdraw. Participants withdrawn due to severe Raynaud's phenomenon or increased digital ulcer size will receive rescue therapy with a systemic vasodilator. Participants requiring rescue medication will continue to be followed for the full 12-week study period, and their data will be included in the Intention-to-Treat (ITT) analysis in compliance with ICH-GCP E6 (R3).

The study will be terminated if the prevalence of serious adverse events (weakened hand grip, paresthesia) in the BTX-A microneedle pad group exceeds 20% (7 cases), or if 15% of enrolled participants (6 cases) experience intolerable pain from the pad, bleeding, or local infection.

Inclusion criteria

• SSc patients aged between 18 and 70 years
• Diagnosed according to ACR/EULAR 2013 classification criteria20
• Having RP with/without DU on fingers or toes
• Understand and able to read and write Thai language
• Stable steroid, immunosuppressant, and vasodilator including CCB, PDE5i for at least 4 weeks before enrollment

Exclusion criteria

• History of allergy or hypersensitivity to Botulinum toxin or ISDN
• Overlap with other connective tissue diseases
• Documented having peripheral arterial disease or vasculitis that affected vascular supply of fingers or toes
• Current use of 2% ISDN cream for treatment of RP
• Current use vasoconstrictor or medication that has vasoconstrictor effect such as ergotamine sulfate, beta-blocker
• Pregnancy and lactating patients
• Bedridden and confined to no self-care
• Evidence of active malignant disease
• Active infection or sepsis
• Localized infection of hand
• Impaired of intrinsic muscle hand function
• Active smoker
• Prior upper extremity vascular surgery, including surgical sympathectomy within 1 month before enrollment