Interaction of intravitreal combination drugs and the effect on the targeted site.
BACKGROUND
After evaluating experimentally the diffusion processes in the retina using peroxidase as a tracer material (previously published work), we found that junctional complexes of the retinal pigment epithelium and retinal capillaries were the major impediment to free diffusion between the retina and choroidal-retinal blood vessels. These experiments indicated that to achieve high therapeutic concentrations of medications inside the eye, it was necessary to administer them by intravitreal injection. Soon after initial experimental work the necessity of combining antibiotics or antibiotics with steroids became obvious. As the use of intravitreal injection grew over the last 2 decades, so did the concept of combination therapy.


METHODS
This review describes potential causes of drug-drug interaction and the rationale for combination therapy when injected into the vitreous cavity, encompassing publications between 1971 and 2008.


RESULTS
We describe the conditions that can cause physical-chemical interactions between the medications and the need for combination therapy for treatment of various intraocular disease processes.


CONCLUSIONS
The intravitreal injection of medication and their combinations has become a part of standard care for many diseases of the retina and choroid. This article reviews the potential interaction of nontoxic doses of medications when injected simultaneously in the vitreous cavity, and disease processes that are now treated with these combination therapies.
Peyman
Gholam A
GA
Department of Ophthalmology and Vision Science, University of Arizona College of Medicine, Tucson, Arizona 85351, USA. gpeyman1@yahoo.com
Conway
Mandi D
MD
Fiscella
Richard
R
D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005128:Eye Diseases / Q000188:drug therapy; D006801:Humans; D007267:Injections; D009883:Ophthalmic Solutions / Q000009:adverse effects* / Q000627:therapeutic use; D014822:Vitreous Body
D009883:Ophthalmic Solutions