How spicy compounds affect blood flow in the feet

The Role of Transient Receptor Potential Channels in Diabetic Peripheral Neuropathy

This research will see if applying cinnamaldehyde, AITC, or capsaicin to the feet of healthy adults changes skin blood flow and whether those responses are consistent across doses, between feet, and across visits.

Quick facts

• Study type: Observational
• Enrollment: 20 (estimated)
• Ages: 18 Years to 45 Years
• Sex: All
• Sponsor: Universitaire Ziekenhuizen KU Leuven (Academic / other)
• Locations: 1 site (Leuven)
• Trial ID: NCT07237022 on ClinicalTrials.gov

What this trial studies

This is an observational study applying three topical TRP-activating compounds (cinnamaldehyde, allyl isothiocyanate, and capsaicin) to the skin of the feet in healthy volunteers. Vascular responses will be measured over time and across multiple doses, and the study will test reproducibility between the left and right foot and between study periods. Eligible participants are healthy white adults 18–45 years old, non-smokers, with BMI between 18 and 30 kg/m². The work is conducted at a single center using non-invasive measurements to characterize time course, dose-response, and inter-period variability of the skin blood flow response.

Who should consider this trial

Good fit: Ideal participants are healthy white adults aged 18–45 who are non-smokers, have a BMI of 18–30 kg/m², and have no significant medical history or regular medications that could confound results.

Not a fit: People with active illnesses, significant allergies, regular medication use that might affect vascular responses, smokers, pregnant or breastfeeding women, or those outside the specified age or BMI ranges are unlikely to be eligible or to gain direct benefit.

Why it matters

Potential benefit: If successful, the results could clarify how TRP channel activation changes skin blood flow and help guide development of topical diagnostics or treatments for peripheral nerve or vascular conditions.

How similar studies have performed: Previous experimental studies using capsaicin and other TRP agonists have reliably produced local vasodilatory responses in healthy volunteers, so this approach builds on established pharmacologic effects.

Eligibility criteria

Inclusion Criteria:

1. Subject is a white male or female ≥18 and ≤45 years of age
2. Subject is a non-smoker for at least 6 months prior to the start of the study
3. Subject has a body mass index (BMI) between 18-30 kg/m²
4. Subject is judged to be in good general health on the basis of medical history, physical examination and vital signs
5. Subject understands the procedures and agrees to participate in the study by giving written informed consent.

Exclusion Criteria:

1. Subject has a history of any illness or disorder which, in the investigator's opinion, might confound the results of the study
2. Subject has a history of significant severe (drug) allergies
3. Subject is a female who is pregnant, breast-feeding or intends to become pregnant, or is of child-bearing potential and is not using an adequate contraceptive method
4. Subject uses any prescription or non-prescription drugs on a regular basis which, in the investigator's opinion, might confound the results of the study
5. Subject currently uses lotions, oils, depilatory preparations, makeup, or other topical treatments on the feet on a regular basis which cannot be discontinued for the duration of the study
6. Subject has eczema, scleroderma, psoriasis, dermatitis or keloids, tumors, ulcers, burns, skin flaps or grafts on the volar surface of the forearm or the dorsum of the feet, or any other skin abnormality that, in the opinion of the investigator, may interfere with the study assessments
7. Subject has excessive hair growth on the volar surface of the forearms or the dorsum of the feet
8. Subject has any of the following vital sign measurements at screening after at least 10 minutes of supine rest: Heart Rate \<40 or \>100 beats/min, Diastolic Blood Pressure \<50 or \>90 mmHg, Systolic Blood Pressure \<90 or \>140 mmHg
9. Subject is unable to refrain from drinking caffeinated beverages (e.g. coffee, tea, cola, …) 24 hours prior to each study visit. Subject is unable to limit their intake of caffeinated beverages to ≤4 cups a day throughout the study
10. Subject is unable to refrain from drinking alcohol 24 hours prior to each study visit, is currently a regular user of illegal drugs, or has a history of substance abuse (including alcohol)
11. Subject is currently participating or has been involved in testing an investigational drug in another clinical study within the last 4 weeks
12. Subject is in a situation or has a condition which, in the opinion of the investigator, may interfere with safe and optimal participation in the study

Where this trial is running

Leuven

• Center for Clinical Pharmacology — Leuven, Belgium (Recruiting)

Study contacts

• Study coordinator: Heleen Marynissen

Conditions Physiological Responses