Anti-vascular endothelial growth factor activity in the bevacizumab and triamcinolone acetonide combination for intravitreal use

Purpose. To find out if the combination for intravitreal use of the antibody bevacizumab (AvastinTM; Genentech, Inc., San Francisco, CA) and triamcinolone acetonide (TA) (Kenacort®; Bristol-Myers Squibb, Anagni, Italy) could affect over time the anti-vascular endothelial growth factor (VEGF) activity of bevacizumab. Methods. Two different combined preparations were obtained, drawing up together 1.25 mg/0.05 mL of bevacizumab and 2 mg/0.05 mL (B+TA2mg) or 4 mg/0.05 mL (B+TA4mg) of TA into insulin syringes with 29-G needle. Control preparations were obtained with bevacizumab and an injectable solution (B). The syringes were stored refrigerated at 4°C. The bevacizumab concentration was measured, through its binding to VEGF-165 isoform, at 48 hours and at 1 week. Results. No preparations showed statistically significant changes in bevacizumab concentration with time (p=0.74 for B+T2mg, p=0.92 for B+T4mg, p=0.57 for B). The B+TA2mg preparations showed a larger percentage of degradation of bevacizumab than the B+TA4mg preparations (28.4% versus 17.6% at 48 hours; 26.4% versus 18% at 1 week). The B control preparations showed the lowest drug degradation: 9.6% at 48 hours and 14.8% at 1 week. Conclusions. After storage at 4°C for 48 hours and 1 week, the combined preparations showed a larger reduction in bevacizumab concentration than the control preparations. No significant change was observed with the length of storage. The preparations obtained mixing 4 mg/0.05 ml of TA and 1.25 mg/0.05 mL of bevacizumab maintained the highest anti-VEGF activity over time. © Wichtig Editore, 2009.