A method and related compositions, including the use of N-acyl derivatives of sarcosine, provide for the delivery of bioactive agents through tissue surfaces such as the skin. The method and composition are particularly well suited for hydrophobic active agents such as serotonin (5HT.sub.3) receptor antagonists (e.g., ondansetron), antipsychotic agents (e.g., risperidone), benzodiazepines (e.g., flumazenil), and progestins (e.g., levonorgestrel).