Intravitreously administered steroids

Intravitreously administered steroids have been used for decades for treating intraocular inflammation and retinal edema. However, during the recent years, increased attention has also been focused on the potential of this treatment to reduce diabetic macular edema. The effect is assumed to be due to... 

Efficacy. Corticosteroids have an inhibitory effect on the growth of fibroblasts (47,48). Triamcinolone acetonide inhibits experimental intraocular proliferation in rabbits (36). Intravitreal injection of 1 mg of triamcinolone significantly reduced both retinal neovascularization and retinal detachment in an experimentally induced rabbit model (36). A 4-mg intravitreal triamcinolone injection inhibited preretinal and optic nerve head neovascularization in a pig model of iatrogenic branch vein occlusion all untreated eyes developed neovascularization by six weeks (49). Intravitreal triamcinolone is also a potent inhibitor of laser-induced CNV in a rat model however, this animal model may not be ideal since laser-induced CNV may be caused by a traumatic repair process or inflammatory response and may be more susceptible to steroids than neovascularization in human disease states (50). In addition, the intravitreal triamcinolone acetonide was administered at the time of laser treatment thus, the treatment may only inhibit new vessel formation and not existing neovascularization. 

The series of clinical trials that led to approval by the U.S. Food and Drug Administration involved 430 eyes in 330 patients. Fomivirsen significantly delayed progression of CMV retinitis in patients with AIDS, including those who had failed treatment with ganciclovir or foscarnet, the first-line therapies. Fomivirsen is administered by intravitreal injection at doses of 165 pg once weekly for three weeks of induction and then once every two weeks. It also can be administered In a dose of 330 pg on days 1 and 15 and then once a month thereafter. Mean maximum retinal concentrations of fomivirsen occur at 2 days, and the elimination half-life after a single, 115-pg dose in monkey retina was 78 hours. There are no systemic side effects. Ocular side effects include Increased intraocular pressure and mild to moderate intraocular inflammation that can be reversed with topical steroid treatment. It is important that side effects be minor, because treatment will be lifelong. 

---