Clinical Research Directory
Browse clinical research sites, groups, and studies.
Session-Order Sensitivity of TS and OA in a Capsaicin Crossover Model
Sponsor: University of Guelph
Summary
Temporal summation (TS) and offset analgesia (OA) are widely used psychophysical endpoints in pain research that index different components of central nociceptive processing. While crossover designs are commonly used in experimental pain studies to reduce between-participant variability, the design-stability of these endpoints under repeated testing during experimental sensitisation is not well characterised. This study compared the design-stability of mechanical TS (Sumscore) and offset analgesia magnitude (OffA) in a two-period, vehicle-controlled crossover trial of capsaicin-evoked secondary hyperalgesia in healthy adults. The primary aim was methodological: to determine whether session-order effects differ between TS and OffA when these are used as outcome measures in two-period crossover designs of capsaicin-induced central sensitisation. Topical capsaicin was used as a reversible experimental intervention to create a controlled, transient state of secondary hyperalgesia rather than as a therapeutic intervention. The study informs endpoint selection in future quantitative sensory testing (QST) crossover trials.
Official title: Session-order Sensitivity of Temporal Summation and Offset Analgesia in a Randomised Crossover Capsaicin Model of Secondary Hyperalgesia
Key Details
Gender
All
Age Range
18 Years - Any
Study Type
INTERVENTIONAL
Enrollment
16
Start Date
2024-05-01
Completion Date
2025-04-30
Last Updated
2026-06-04
Healthy Volunteers
Yes
Interventions
Topical 0.075% capsaicin cream (Zostrix)
5 mL of 0.075% capsaicin cream (Zostrix; Hi-Tech Pharmacal, Amityville, NY, USA) applied to a 5 x 10 cm target region on the lateral elbow and to bilateral C5-C6 cervicothoracic dermatomes (total 15 mL). The cream was massaged into the skin by a gloved investigator until no residue was visible. Used as an experimental probe to evoke transient, reversible secondary hyperalgesia; not under therapeutic evaluation.
Topical vehicle lotion (Lubriderm)
5 mL of inert vehicle lotion (Lubriderm; Johnson \& Johnson, Montgomery, NJ, USA) applied to the same dermatomes as the capsaicin condition (total 15 mL), using the identical preparation and massage technique. Matched to the capsaicin cream for colour and texture.
Locations (1)
Human Health Sciences, University of Guelph
Guelph, Ontario, Canada