ABSTRACT
Drugs and excipients have different sensitization capacities for inducing contact allergy. The risk of skin reactions produced by chemicals depends on their inherent allergenicity and ability to penetrate into the normal skin or damaged skin. As fully described in earlier chapters, the penetration of chemicals into the skin depends on skin condition, anatomical site, chemical characteristics of the substance, lipid solubility and concentration of the chemical. Penetration is also influenced by external factors, especially solvents, surfaceactive agents, alkalies, moisture, temperature, extreme dehydration, and mechanical effects. The length of time that a substance contacts the skin is of great importance. Skin irritation influences the cells of the skin and results in an increased sensitization risk. Such cell damage can be produced by variety of chemicals or by mechanical means.
