Percutaneous absorption factors affecting

Factors and Chemicals that Affect Percutaneous Absorption... 

Riegelman, S. Pharmacokinetics pharmacokinetic factors affecting epidermal penetration and percutaneous absorption. Clin. Pharmacol. Ther. 1974, 16, 873-883. 

SOME FACTORS AFFECTING THE PERCUTANEOUS ABSORPTION OF CW AGENTS... 

Monteiro-Riviere, N.A., 1996, Anatomical factors affecting percutaneous absorption, in EN. Marzulli and H.I. Maibach (eds.), Dermatotoxicology, 5th ed., Washington, D.C. Taylor and Francis, pp. 3-17. 

Absorption across the skin has long been recognised as an important primary route of entry of toxic agents into the body. However, percutaneous absorption is complex, variable and affected by a variety of factors and still defies simple measurement. The rates of skin penetration are unknown for most liquids, solids and gaseous substances. 

An understanding of the percutaneous absorption is essential when evaluating the potential of a chemical to cause skin disorders or systemic toxicity. This section provides a brief description of the barrier function of the skin and considers the factors affecting percutaneous absorption. Although this section only discusses the barrier function of the skin, it must be remembered that a chemical coming into contact with skin can also evaporate from the skin surface, bind to stratum corneum or become metabolised. 

Investigation of percutaneous absorption without the influence of other pharmacokinetic factors that may affect cutaneous uptake... 

For instance, elderly people are not only affected more often by contact dermatitis because of their reduced epidermal barrier, they also show more severe symptoms of this disease (Patil and Maibach 1994 Ghadially et al. 1995). Environmental influences, such as cold and low ambient humidity, are important factors in decreasing the water content of the stratum corneum (Mozzanica 1992). Cold alone may also reduce the plasticity of the horny layer, with consequent cracking of the stratum corneum. Occlusion increases the water content of the stratum corneum, with consequent enhanced percutaneous absorption of water-soluble substances. A list of factors influencing the irritancy potential of substances are summarised in Table 3. 

Other aspects of formulation such as the nature of the binary or ternary vehicle (oil-surfactant, water-surfactant or oil-water-surfactant, respectively) have been considered recently [151], Addition of polysorbate 80 to the aqueous phase has no significant effect on the epidermal transport of ethanol, but a significant reduction in the transport of the less soluble octanol results, in line with the arguments presented above in isopropyl myristate, octanol transport is not affected by the solubilizer while that of ethanol is decreased. In the ternary systems identified in Fig. 7.35, the results in Table 7.14 were obtained indicating a general decrease in permeability constants for ethanol, butanol and octanol. The viscosity of the vehicles was not a factor although this varied from 1 to 39 X 10 cP. In the ternary systems a surfactant will distribute itself between the aqueous and non-aqueous phase quantitative prediction of permeation is made difficult even with data on the transport properties of the permeants in the individual phase. The results indicate that the percutaneous absorption of the... 

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