A Phase 4 interventional study of Patch 1 (Expired) and Patch 2 (non-expired) in Allergic Contact Dermatitis, sponsored by University of Calgary. Not yet recruiting at 1 site in Canada. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-08-14.
Sponsored by University of Calgary · Phase 4, Interventional, and Diagnostic
Patch testing remains the gold standard in the diagnosis of allergic contact dermatitis. Patches used in testing consist of a wide spectrum of allergens, with variability in the stability of products over time. Due to limited allergen stability, careful storage and preparation is needed to prevent product degradation over time. Expiration dates are provided by manufacturers to ensure stability and reactivity, while minimizing the risk of product degradation contributing to inaccurate testing results. Preparation of patch series can be time intensive and procurement of allergens comes with an associated economic burden. Expired allergens are not routinely used in patch testing, however many clinics have expired allergens accessible. There is paucity of evidence comparing the reactivity of expired vs non-expired patch series. If expired allergens remain effective, this could result in significant cost-savings and accessibility implications for dermatology practice.
In brief, review of the medical literature showed two comparable studies out of India and Spain suggesting that expired allergen series may be used beyond their labeled expiry dates, with some variability noted amongst duration of expiry, that the investigators will also aim to analyze.
Regarding allergen stability, there were also several studies focused on this domain. The European Society of Contact Dermatitis (ESCD) released guidelines in 2015, outlining optimal methods for allergen storage such as storage at 4 degrees celsius and strict protection from ultraviolet light exposure. While most allergens are dispersed in petrolatum (white soft paraffin), some substances are better tested in solutions such as water (aqueous) or ethanol. Several allergens with high vapour pressure require more frequent renewal and strict storage conditions such as fragrance chemicals, acrylates and isocyanates. Other substances such as glutaraldehyde in petrolatum (pet.) and formaldehyde in aqueous solution (aq.) are susceptible to instability and deterioration. An additional study assessed volatility over time of several select compounds and described high volatility in acrylates, glutaraldehyde, and fragrances, while describing partial volatility of formaldehyde and low volatility of nickel sulfate.
Study participants will include all eligible adults seen in patch testing clinic who maintain an indication for patch testing and consent to participation. The study will be utilizing 10 allergens from the North American Contact Dermatitis Group (NACDG) 80 Series for inclusion in the study.
The allergen selections are primarily based on compounds with a higher likelihood for volatility, in addition to inclusion of two comparator compounds with lower volatility. Expiration intervals include 1 year, 2 years, 3 years, and 4 years. The compounds selected are as follows, including their dispersion compound: nickel sulfate hexahydrate (5% pet.), cobalt (II) chloride hexahydrate (2.5% pet.), hydroperoxides of linalool (1% pet.), hydroperoxides of limonene (0.3% pet.), fragrance mix 1 (8.0% pet.), myroxylon pereirae resin (balsam of Peru) (25.0% pet.), methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) (0.02% aq.), formaldehyde (2.0% aq.), tixocortol-21-pivalate (1.0% pet.), and budesonide (0.1% pet.).
The patch testing results will be compared to corresponding non-expired allergens from the same manufacturer with the same preparation tested simultaneously. Both series will be placed simultaneously in differing locations on the participant's back, ensuring both are placed in sun protected areas with no underlying dermatitis.
Once in clinic, standard patch test series are applied on patch testing day, with the participant instructed not to shower or scratch the area throughout testing. At 48h, the patches are removed and photos are taken of the participant's back which are sent to the Dermatologist for virtual reading. At either 96h or 120h, the participant returns to the clinic for final reading. Both morphology and intensity of positives are graded on a standard patch test scale (irritant reaction), +/- for doubtful, + for erythema and infiltration, ++ for edematous or vesicular and +++ for spreading, bullous or ulcerative. Positive allergens scored + or greater are considered a true allergic contact allergen and assessed for relevance based on clinical context. The Dermatologist provides information sheets on all positive allergens, counsels on the relevance to their clinical history and allergen avoidance going forward, as well as providing the participant with a safe product list via the ACDS Contact Allergen Management Program (CAMP) database.
The investigators are aiming for enrolment of 100 participants which should theoretically provide the study with at least 5-10 participants testing positive to each of the four listed allergens with higher volatility and 20+ participants testing positive to the allergens with lower volatility. The investigators are aiming to assess concordance between expired and non-expired allergen reactions (positive vs negative), in addition to agreement in reaction intensity, differences in morphology, rates of false positives/negatives compared to control and concordance of irritant reaction between interventions.
The study will serve to lend valuable evidence as to whether expired allergens maintain clinical utility and could serve to reduce product waste, lower the economic burden and further improve accessibility of patch testing for use in resource limited settings.
52 studies on the registry are indexed under Dermatitis, Allergic Contact; 11 are open to participants now.
This study's planned enrollment of 100 is above the median of 45 across 41 interventional studies indexed under Dermatitis, Allergic Contact.
Browse Dermatitis, Allergic Contact studies →University of Calgary is the lead sponsor of 703 studies on the registry; 196 are open to participants now.
Of its 10 completed or terminated interventional studies of FDA-regulated products, 2 (20%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
All enrolled participants will be simultaneously patch tested with both expired and non-expired patches. Therefore, there is no difference in intervention amongst study participants.
Biological: Patch 1 (Expired) · Biological: Patch 2 (non-expired)
All enrolled participants will be simultaneously patch tested with both expired and non-expired patches. Therefore, there is no difference in intervention amongst study participants.
All enrolled participants will be simultaneously patch tested with both expired and non-expired patches. Therefore, there is no difference in intervention amongst study participants.
Patch Testing Response (Positive/Negative) Concordance Rate (%) Between Non-Expired and Expired Allergens
Each allergen will be graded on response using a standard patch test scale including: irritant reaction \['IR'\], '+/-' for doubtful, '+' for erythema and infiltration, '++' for edematous or vesicular and '+++' for spreading, bullous or ulcerative response that will be graded by the participating Dermatologist. Reactions graded '+', "++", or "+++" are consider a positive result. Concordance rate will be expressed as a percentage (%) between tested allergens that were non-expired and that were expired (i.e. Nickel sulfate hexahydrate was found to have a 92% concordance rate, meaning that in 92% of cases, the Nickel allergen in the non-expired and expired patches were both found to both be either positive or negative while in 8% of cases the response differed per the scale listed above.)
Time frame: Standard patch test series are applied on Day 0. Participant removal of patches on Day 2 and self photos taken and sent to Dermatologist for virtual reading. Final reading completed in clinic by Dermatologist on Day 4 or 5, recording reaction scores.
Reaction/Morphology Scoring Concordance (%)
For each positive allergen, severity (i.e. '+/-', '+', '++', "+++") and morphology (i.e. erythema, infiltration, edematous, vesicular, bullous, ulcerated) will be recorded. Concordance rate will be expressed as a percentage (%) between tested allergens that were non-expired and that were expired (i.e. Nickel sulfate hexahydrate was found to have a 92% concordance rate, meaning that in 70% of cases, the Nickel allergen in the non-expired and expired patches were both found to have the exact same severity and morphology, while in 30% of cases the severity and/or morphology differed per the scale listed above.)
Time frame: Standard patch test series are applied on Day 0. Participant remove patches on Day 2, photos taken and sent to Dermatologist for virtual reading. Final reading completed in clinic by Dermatologist on Day 4 or 5, recording reaction scores, morphology.
Stability Concordance (%) Amongst Mediums
Each allergen is suspended within a medium, either petrolatum or aqueous solution. Not only will concordance (%) of positive and negative reactions be assessed amongst allergens and compared between non-expired and expired, but also between mediums to determine if there is a difference in stability over time amongst mediums used to determine if particular mediums result in degradation over time.
Time frame: Standard patch test series are applied on Day 0. Participant remove patches on Day 2, photos taken and sent to Dermatologist for virtual reading. Final reading completed in clinic by Dermatologist on Day 4 or 5, recording reaction scores, morphology.
Irritant Reaction Rates (%)
Final patch reading will score reactions on a standarized scale, with irritant reaction representing a negative reaction. However, we will compare rates and concordance (%) of irritant reactions between allergens to determine if their is reproducibility, or if expired allergens result in differing rates of irritant reactions. (i.e. Nickel sulfate allergen was shown to have a 50% increased rate of irritant reactions between the expired to non-expired allergens, meaning that Nickel resulted in an irritant reaction in 6 cases of the expired Nickel and 4 cases of the non-expired Nickel, suggesting that expired Nickel allergens may become more irritating over time, resulting in more irritant reactions.
Time frame: Standard patch test series are applied on Day 0. Participant remove patches on Day 2, photos taken and sent to Dermatologist for virtual reading. Final reading completed in clinic by Dermatologist on Day 4 or 5, recording reaction scores, morphology.
Plan to share: No — Aside from eventual publication of study results to help guide practice, we will not be sharing granular study data with other researchers for expansion of the study.
This study is not yet recruiting, as verified in Jul 2026. You cannot join it, but the record below documents what was studied.
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Dermatitis, Allergic Contact →