Safety evaluation of ocular drug delivery formulations: techniques and practical considerations

Toxicol Pathol. 2008 Jan;36(1):49-62. doi: 10.1177/0192623307310955.


Development of new drug candidates and novel delivery techniques for treatment of ocular diseases has recently accelerated. Treatment of anterior-segment diseases has witnessed advances in prodrug formulations and permeability enhancers. Intravitreal, subconjunctival, and periocular routes of administration and sustained-release formulations of nanoparticles and microparticles, as well as nonbiodegradable and biodegradable implants to deliver drugs to the posterior segment of the eye, are becoming popular therapeutic approaches. Without adequate regulatory guidance for ocular drugs, such routes of administration and novel formulations can pose unique challenges to those involved in designing nonclinical programs, including considering clinical and nonclinical factors and choosing species, strains, and ocular toxicity parameters. Toxicologic pathologists also contribute practical experience to evaluating morphological effects of these novel formulations. Lastly, understanding species' anatomical differences is useful for interpreting toxicological and pathological responses to the eye and is important for human risk assessment of these important new therapies for ocular diseases.

Publication types

  • Review

MeSH terms

  • Drug Administration Routes
  • Drug Carriers
  • Drug Delivery Systems / methods*
  • Drug Implants / adverse effects
  • Drug-Related Side Effects and Adverse Reactions*
  • Eye / anatomy & histology
  • Eye / drug effects
  • Eye Diseases / drug therapy*
  • Eye Diseases / metabolism
  • Humans
  • Nanoparticles / adverse effects
  • Pharmaceutical Preparations / administration & dosage
  • Prodrugs / administration & dosage
  • Prodrugs / pharmacokinetics
  • Toxicity Tests


  • Drug Carriers
  • Drug Implants
  • Pharmaceutical Preparations
  • Prodrugs