Pharmacology and toxicology of novel drug delivery systems. Regulatory issues.

The lure of optimising the effect of the drug on the body (pharmacodynamics) and the body on the drug (pharmacokinetics) has produced an alternative group of products designed to achieve specialised delivery and/or disposition of drugs. A toxic drug may be used in more effective concentrations by targeting the drug to its site of action and decreasing additional systemic toxicity. Four possible regulatory situations for delivery system and drug have been identified, and generalisations regarding the non-clinical studies needed for the initiation of clinical trials and New Drug Application (NDA) have been described. Problems associated with the identification of appropriate controls have been included, and the importance of basing the choice upon a scientifically rational evaluation of the pharmacodynamic and pharmacokinetic study results emphasised, along with the significance of conducting the non-clinical evaluation using the final formulation.