Mitra Ashim K. Ophthalmic Drug Delivery Systems

2nd edition. — CRC Press, 2003. — 847 p.The second edition of this text assembles significant ophthalmic advances and encompasses breakthroughs in gene therapy, ocular microdialysis, vitreous drug disposition modelling, and receptor/transporter targeted drug delivery.A major goal of pharmacotherapeutics is the attainment of an effective drug concentration at the intended site of action for a desired length of time.
Efficient delivery of a drug while minimizing its systemic and/or local side effects is the key to the treatment of ocular diseases. The unique anatomy and physiology of the eye offer many challenges to developing effective ophthalmic drug delivery systems, but the knowledge in this field is rapidly expanding. Systems range from simple solutions to novel delivery systems such as biodegradable polymeric systems, corneal collagen shields, iontophoresis, and viral and nonviral gene delivery systems, to name a few. An increase in our understanding of ocular drug absorption and disposition mechanisms has led to the development of many of these new systems.
The first edition of this book laid the foundation necessary for understanding barriers to ophthalmic drug delivery and to review the conventional systems available and/or in various stages of research and development. Since then, significant advances have been made in understanding the molecular mechanisms involved in ocular drug transport.
The book begins with a brief discussion on the anatomy and physiology of the eye relevant to ocular drug delivery. The latest techniques, such as microdialysis, and models developed to study ocular drug disposition are discussed. A review of both the conventional and novel delivery systems follows. The book stresses the fact that simple instillation of drug solution in the cul-de-sac is not always acceptable and emphasizes the need for the development of newer and more efficient systems. The book concludes with the basic information required for pharmaceutical scientists to protect their inventions.
Part I investigates the fundamental considerations in ocular drug delivery. The three chapters in this part review the relevant ocular anatomy and physiology, the constraints imposed by the eye upon successful delivery, and the associated ion and solute transport processes in the eye. They provide information on the various transport processes as well as recently identified drug efflux pumps, which regulate the transport of endogenous and exogenous substances.
Part II opens with a discussion of pharmacokinetics relevant to ocular drug delivery. The next chapter discusses the pharmacokinetic processes guiding the ocular disposition and expands on the pharmacokinetic/pharmacodynamic modeling processes to determine the appropriate dosage regimen.
This chapter is followed by a detailed discussion of the various mathematical models developed to describe the distribution and elimination
of drugs from the vitreous. This part also includes chapters dealing with the application of microdialysis technique to study ocular drug delivery and disposition, and the applicability of the microdialysis sampling approach for the examination of ocular pharmacokinetics and dynamics of ophthalmics.
Part III is divided into conventional and advanced drug delivery systems. The first section deals with such conventional systems as collagen shields, iontophoresis, microparticulates, and dendrimers. These chapters have been updated to include advances in ocular drug delivery achieved in the past decade. The second section examines the delivery of macromolecules to treat various ocular pathologies. The reader will find more information on the recent developments in animal models of retino-choroidal diseases. The viral and nonviral gene delivery systems introduced in this section are still in their infancy but have the potential to provide enormous therapeutic benefits. This section also focuses on the advances in treating retinal degenerative diseases. The last chapter in this section discusses the principles and delivery aspects of gene, oligonucleotide, and ribozyme therapy.
Part IV provides information on regulatory and patent considerations. Pharmaceutical scientists will gain knowledge of the regulations governing animal and human testing and ultimately the release of the product commercially for public use. The final chapter conveys the legal issues involved in protecting inventions and the basic legal requirements for obtaining patents.