BODY CARE
29
Biomimetic hydroxyapatite for deodorant
Guglielmo Bifulco, Giorgio Tosti, Francesco Rastrelli, Gianbattista Rastrelli – Kalichem
The current landscape of sweat and body odour control products typically relies on traditional active ingredients like aluminium chloride or aluminium chlorohydrate-based salts. Although very effective in reducing sweating, these compounds may release at different amounts hydrochloric acid, which can lead to undesired side effects on the skin.1 Firstly, hydrochloric acid can irritate the skin,
reducing the product’s skin tolerance and user compliance. Moreover, formulas containing aluminium-
based salts such as chloride or chlorohydrate, and aluminium/zirconium chlorohydrate are not always so accepted. In recent times, issues related to
environmental impact of aluminium salts as well as skin health and irritation are posing concerns in the use of these ingredients. Moreover, by lowering the pH it can disrupt the skin’s microbiota.2
Additionally, the
mechanism of action of these salts—based on the obstruction of sweat ducts—may cause functional damage to sweat glands and impair the physiological perspiration process.3 To address these issues associated with
conventional approaches, Kalichem developed a new ingredient based on a patented technology. The speciality, named Deohap Dry (main active and excipients INCI: Calcium/ Magnesium/Zinc Hydroxyapatite, clay minerals, zinc PCA; hereafter described as the HAP complex), has been specifically designed to be gentle, effective and ideal to be used in various formulation systems. The core innovation relies on the biomimetic
hydroxyapatite, functionalized with zinc and magnesium ions, to obtain a broad range of beneficial cosmetic effects, such as: ■ Odours and sweat adsorption ■ Deodorizing ■ Bacteriostatic action ■ Skin homeostasis ■ Microbiota balance Biomimetic hydroxyapatite is structurally and functionally similar to the naturally occurring form in the human body. It is obtained through an exclusive technology differentiating from stoichiometric hydroxyapatite.4,5 The unique properties of this mineral
contribute directly to its effectiveness in reducing body odours and sweat. The high hydration capacity and water affinity of the material enable effective adsorption of sweat. Its rough, porous surface provides a large
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surface area, enhancing its interaction with sweat components. Its electrophilic nature enables, furthermore, to trap volatile molecules,6
thus effectively
neutralizing body odours. The substitution of divalent ions such as zinc and magnesium in the hydroxyapatite lattice enhances its electrophilic properties, facilitating stronger interactions with volatile molecules like ammonia, hydrogen sulfide. This enables the mineral to trap malodourous substances, thereby exerting its deodorizing effect.
Sweat control formulation challenges The actives commonly used in anti-perspirants and deodorants, e.g. aluminium salts, triclosan, natural ingredients including antibacterial extracts, may be included in different cosmetic forms – such as sprays, sticks, roll-ons, aerosols, and creams - but require to be formulated
differently for each type to ensure effectiveness, stability and safety. Specific challenges for the fulfillment of
each of these factors are following described. Commonly used salts with anti-perspirant action can be present in sticks, creams, roll- ons, and, under certain conditions, aerosols; nonetheless they require specific and extremely acidic pH values for overall stability and functionality achievement, strongly influencing and limiting the inclusion of other potentially synergistic ingredients. Antibacterial benchmark ingredients can be
formulated in both liquid (roll-on or spray) and solid (stick) forms, but the concentration must be tailored to the vehicle to avoid irritation or destabilization. The vehicle compatibility represents
another relevant topic as aerosols require the use of propellants and a highly dispersible
February 2025 PERSONAL CARE
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