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Study to Evaluate the Influence of Hydrochlorothiazide on Dermal Photosensitivity and DNA Stability - a Pilot Study (HCTox Study)

A Randomized, Double-blind, Placebo-controlled Study to Evaluate the Influence of Hydrochlorothiazide on Dermal Photosensitivity and DNA Stability - a Pilot Study (HCTox Study)

Status
Completed
Phases
Phase 1
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04654312
Enrollment
30
Registered
2020-12-04
Start date
2021-01-18
Completion date
2021-07-22
Last updated
2025-08-11

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Photosensitivity

Brief summary

The clinical trial is designed as a national, prospective, single-center, double-blind, parallel group, randomized, controlled, interventional trial to investigate whether a therapy with HCT compared with placebo can affect dermal photosensitivity and DNA stability.

Detailed description

Previously published retrospective analyses leading to the official warning about the use of hydrochlorothiazide (HCT). The underlying pilot study examins, if the intake of HCT leads to increased dermal photosensitivity and in combination with UV-exposition to a DNA-damage of the skin. Up until today, there is no prospective, randomized, placebo-controlled trial investigating the impact of HCT on dermal photosensitivity in greater detail. The pilot trial is designed as feasibility study to clarify the impact of HCT on dermal photosensitivity. This may facilitate evidence-based recommendations as to whether or not HCT increases the risk for skin cancer. Of note, HCT is one of most frequently prescribed drugs in Germany.

Interventions

DRUGHydrochlorothiazide

Please see arm descriptions

DRUGPlacebo

Please see arm descriptions

Sponsors

Universität des Saarlandes
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
OTHER
Masking
DOUBLE (Subject, Investigator)

Intervention model description

National, prospective, single-center, double-blind, parallel group, randomized, controlled, interventional Trial.

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes

Inclusion criteria

1. The subject is willing and able to participate and provides written informed consent; 2. Healthy subjects with no concomitant medical conditions; 3. Age ≥ 18 years; 4. The subject is willing to take HCT 25 mg a day although not clinically indicated; 5. The subject is willing to undergo controlled UV-exposition although not clinically indicated; 6. Skin type I - IV.

Exclusion criteria

1. History of any cardiac disease; 2. History of any dermatologic disease; 3. Renal insufficiency (eGFR \<60 ml/min/1.73m²); 4. Intake of photosensitive substances, especially intake of HCT; 5. Frequent, above-average, UV exposition (naturally or artificially); 6. Known hypertension; 7. Known electrolyte disbalance; 8. Systolic blood pressure at baseline \<100 mmHg; 9. Skin type V and VI; 10. History of severe diseases, which could endanger the safety of study participant; 11. Known unresolved history of alcohol dependency or drug abuse or any other kind of dependencies 12. Intake of any of the following medications or substances: Betablockers; nitrates; barbiturates; phenothiazines; tricyclic antidepressants; vasodilatory drugs; ACE-inhibitors; NSAIDs; salicylates; phenytoin; Insulin; oral antidiabetic drugs; vasoconstrictors; glycosides; substances lowering blood-urea levels; substances causing a Long-QT-Syndrome; chinidine; carbamazepine; cyclosporine; cholecalciferol; potassium salts; amantadine; allopurinol; methyldopa; cholestyramine; colestipol; other diuretics; lithium; cytostatic drugs; 13. Women in childbearing age and not using medically acceptable effective contraception refer to CTFG: The study population includes female of childbearing potential. Female of childbearing potential have to agree to comply with the applicable contraceptive requirements of the protocol for the duration of the study or having post-menopausal status or be permanently sterilized (at least 6 weeks post-sterilization). Highly effective contraception is defined as a contraceptive method with failure rate of less than 1 % per year when used consistently and correctly and when applicable, in accordance with the product label; 14. Subject is pregnant (e.g., positive ß-hCG test) or is breast feeding; 15. Hypersensitivity to the active substance, to HCT or any of its excipients.

Design outcomes

Primary

MeasureTime frameDescription
Changes in subjects´ minimal-erythema-dose (MED).2 weeksThe MED is the minimal erythema dose, meaning the minimal dose of energy (in this case provided by UV-exposition) per area that leads to a clinically visible skin reaction, mainly a slight reddening. The MED is assessed by a clinical tool called the light-stair.
Amount of excretion of pyrimidine-dimers (PD) in urine.26 daysChanges from Baseline Visit to Day 26

Secondary

MeasureTime frameDescription
Changes in blood-serum vitamin-D levels.26 daysChanges from Baseline Visit to Day 24
Changes in blood pressure.26 daysChanges from Baseline Visit to Day 24

Other

MeasureTime frameDescription
Changes in kidney function (eGFR)26 daysChanges from Baseline Visit to Day 24
Changes in blood count26 daysChanges from Baseline Visit to Day 24
Changes in electrolytes (Na+, K+)26 daysChanges from Baseline Visit to Day 24

Countries

Germany

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 8, 2026