Metrics and Clinical Relevance of Percutaneous Penetration and Lateral Spreading

<b><i>Background:</i></b> Percutaneous penetration of urea in vivo in man has been documented. If urea can penetrate the skin, it may also move laterally. Lateral spreading of topical substances leads to unpredictable penetration dynamics and increased skin surface area exposure. <b><i>Methods:</i></b> The ability of urea, a low molecular-weight hydrophilic model, to penetrate the stratum corneum...