Concentrations of unbound bevacizumab in the aqueous of untreated fellow eyes after a single intravitreal injection in humans

Purpose: To determine the concentration of unbound bevacizumab in untreated fellow eyes after contralateral intravitreal injection of bevacizumab. Methods: A total of 18 eyes received intravitreal injections of 1.5 mg bevacizumab. Nine probes were obtained in the injected eye and nine in the fellow eye. Each group contained three individual eyes. Aqueous humour samples were obtained during uneventful phacoemulsification at three intervals 1-7 days (group a), 8-12 days (group b) or 13-28 days (group c). Results: In untreated fellow eyes, the concentration of unbound bevacizumab was below the detectable limit of the ELISA (5 ng/ml in all samples). The mean concentration of unbound bevacizumab in the injected eye declined from 28.6 mu g/ml (group a), 16.5 mu g/ml (group b) to 7.4 mu g/ml (group c). Conclusions: There are no pharmacological indications for a significant concentration of unbound bevacizumab in the anterior chamber of contralateral eyes in humans.