Formulations

To date, very few preparations have characteristics that make them especially suited for any of the user groups given in Table 1 [10], although some general remarks can be made: current protective products against water-based irritants (soap, alkaline, acids) act in a rather nonspecific way by depositing mineral oils, isopropylmyristate, long-chain alcohols, fats, or waxes on top of the skin or into the outer stratum corneum cell layers in order to create a physical lipids barrier. Water repellants, like silicone oils or perfluoroether, are sometimes included. However, because these are highly inert molecules, high percentages of emulsifier are required to stabilize such formulations. This means that the net increase in protective properties with these supplements is disappointing (water-dragging effect), while high emulsifier concentrations may also cause irritation. More successful attempts have been made by including chemicals that are intended to bind to skin constituents, such as Eucoriol (sodium bischlorophenyl sulfamine), which is included in a water-in-oil (W/O) ointment. A disadvantage is that the product is rather greasy on the skin. The emulsion type of preparations against water-based irritants is usually W/O, although there are some exceptions: a high-fat product in an oil-in-water (O/W) fatty cream*, and a product with petroleum jelly and silicone oil in a gel structure. The latter products have better cosmetic properties. Despite the fair-to-good protective properties offered by W/O products, their poor cosmetic properties make these products less suitable for use by, e.g., hairdressers and hospital nurses.

Recently, O/W emulsions, including CM glucan, a polysaccharide isolated from baker's yeast, was proposed and tested for its protective properties in surfactant-challenged skin [11]. The clinical value of this type of formulation has not been shown, however. In order to increase cosmetic properties for BP products, foam-based products have been developed. An example is a foam containing stearic acid and dimethylpolysiloxane. Unfortunately, comparative tests have shown that the apparent advantage in cosmetic properties for this product does not extend to acceptable protective properties [12].

Cream and gel preparations for the prevention of nickel-induced ICD with ethylene diamine as a chelator have been made and tested in in vitro tests and patch tests [13]. §

Despite encouraging results in these types of tests, clinical efficacy of this type of preparation has not been shown. For protection against organic solvents, O/W creams are recommended [14], although in efficacy tests using toluene, or poison ivy extracts, this is not ^ well accomplished with currently marketed products [1,10,15], thus casting doubt on this ^ recommendation. Unfortunately, it can be stated that despite the many technological ad-

! Product protected by, e.g., Canadian patent 1200504.

Table 1 Product Users and Properties Needed to Fulfill Users' Needs for Protective Formulations

Product properties *

Protective properties against

Wash/Wear

Soap Aggressive Diluted Diluted Dehydrating Usergroup solutions chemicals acid alkali polar solvents

Apolar solvents

Wash-off Friction

Cosmetic properties

Cooks, sandwich makers, meat-industry + workers

Hairdressers ++ ++ + + +

+ +

+ +

Packers

+ +

-/ +

Mechanics + + +

+ +

+

-

Confectionary workers

+ +

+ +

Laboratory technicians + + +

+

+

+

Farmers

+ + +

-

Graphic-industry workers + + +

+

+

-/ +

Hospital nurses + + + +

+ +

+

: On a scale of —, not important/needed; +, important/needed; + + , very important.

: On a scale of —, not important/needed; +, important/needed; + + , very important.

Figure 3 Skin-protective properties and suitability in daily-use characteristics for differential topical protective formulations.

vancements that have been made in pharmaceutical and cosmetic topical formulation science, and that have brought a better understanding of composition-properties relationships [16,17,18], this has not yet been translated into efficacious BP products for all user groups.

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