Copper sulphate, anhydrous

What is copper sulphate, anhydrous?

Copper sulphate, anhydrous is a chemical compound of the essential trace mineral copper. The full chemical name is copper(II) sulfate, and the anhydrous form means it contains no water of crystallisation. In the registered trials, copper appears as copper sulfate pentahydrate 2%, a hydrated form prepared for cutaneous use in patch testing.^[1][1] A related product, copper sulfate 50mg/50ml solution for infusion, is listed in the NHS dictionary of medicines as a prescribable product for intravenous use.^[2] Copper is also approved in Canada as a natural health product ingredient in oral mineral supplements.^[4]

How does copper sulphate, anhydrous work?

In the body, copper functions as a structural component in many proteins involved in energy and iron metabolism, production of neurotransmitters, formation of connective tissue and endogenous antioxidant defence.^[3] In the registered clinical trials, however, copper is not used for its nutritional role. It is applied to the skin as part of a diagnostic metal panel to test whether a person has an allergic reaction to copper and other metals.^[1][1] The patch test works by placing a small amount of the allergen on the skin under occlusion and observing whether a localised skin reaction develops.

Which conditions is it used or studied for?

• Allergic contact dermatitis — a delayed skin reaction that occurs when the skin comes into contact with a substance to which a person is sensitised. The registered trials test whether copper and other metals trigger this reaction.^[1][1]
• Eczema — a broader term for inflammatory skin conditions. One trial record lists eczema alongside allergic contact dermatitis as a studied condition.^[1]

How is copper sulphate, anhydrous given?

In the registered trials, copper is given by cutaneous use as a patch test allergen. The intervention is described as copper sulfate pentahydrate 2% applied in a volume of 20 microlitres to the skin.^[1][1] The trial also compares two formulations: an investigational hydrogel and a reference petrolatum-based preparation. Separately, a licensed medicinal product exists as a solution for infusion for intravenous use, containing copper sulfate 50mg in 50ml.^[2] Oral copper supplements are also approved as natural health products in Canada.^[4]

What do the clinical trials show?

Two registry records describe a phase 3 interventional study of a metal panel patch test that includes copper sulfate pentahydrate 2%. One record has status authorised and enrolled 395 participants; the other has status withdrawn and had a planned enrollment of 300 participants.^[1][1] Both records list the same primary outcome: the concordance, or agreement, between the hydrogel investigational allergen and the petrolatum reference allergen, calculated using Cohen's kappa and by positive and negative percent agreement.^[1][1] The study objective is to evaluate the diagnostic efficacy and safety of the investigational allergens and the overall safety and performance of the investigational panel device.^[1][1]

What side effects are known?

Copper imbalances have been linked to the pathogenesis of several chronic inflammatory diseases, although the scoping review notes that no biochemical index has been found suitable for detecting marginal copper deficiency or marginal copper toxicity.^[3] The registered trial brief summary states that the safety of the investigational allergens is part of the study objective, but no specific adverse event data are reported in the registry records.^[1][1]