Changes of serum VEGF concentration after intravitreal injection of Avastin in treatment of diabetic retinopathy.

PURPOSE: Avastin (bevacizumab) intravitreal injections are widely used for treatment of diabetic retinopathy. The aim of our study was to analyze effect of 1.25 mg of intravitreal Avastin on serum concentration of vascular endothelial growth factor (VEGF) in diabetic patients.
METHODS: Participants were 10 diabetic patients on insulin therapy, without any other eye or systemic disease, and no kidney disfunction. Both eyes of diabetic patients were injected simultaneously with 1.25 mg of intravitreal Avastin, as a first step in treatment of nonproliferative diabetic retinopathy with clinically significant macular edema (4 patients), and of proliferative diabetic retinopathy (6 patients). Fluorescein angiography was performed prior to and laser therapy followed 1 month after Avastin treatment. VEGF concentration in patients serum was measured by ELISA technique: on the day of the Avastin administration, and 1, 7, and 28 days after intravitreal injection.
RESULTS: In all analyzed participants, 24 hours after Avastin treatment, serum levels of VEGF were lower then basal (preinjection value). Maximal reduction of serum VEGF was noted on the 7th postoperative day. Twenty-eight days after, VEGF level in serum was raised, without completely reaching basal preoperative concentrations in most patients.
CONCLUSIONS: Intravitreal injections of anti-VEGF drugs have an effect on decreasing systemic VEGF values. Rhythm of changes in serum VEGF concentrations and lowest detected concentration on the seventh postinjection day are according to pharmacokinetics of Avastin in serum and vitreous, reported by similar studies. The small number of patients involved in this pilot study implicates the need for further studies.