Vitreous pharmacokinetics and electroretinographic findings after intravitreal injection of acyclovir in rabbits

Abstract

OBJECTIVES:Acute retinal necrosis is a rapidly progressive and devastating viral retinitis caused by the herpesvirus family. Systemic acyclovir is the treatment of choice; however, the progression of retinal lesions ceases approximately 2 days after treatment initiation. An intravitreal injection of acyclovir may be used an adjuvant therapy during the first 2 days of treatment when systemically administered acyclovir has not reached therapeutic levels in the retina. The aims of this study were to determine the pharmacokinetic profile of acyclovir in the rabbit vitreous after intravitreal injection and the functional effects of acyclovir in the rabbit retina.METHODS:Acyclovir (Acyclovir; Bedford Laboratories, Bedford, OH, USA) 1 mg in 0.1 mL was injected into the right eye vitreous of 32 New Zealand white rabbits, and 0.1 mL sterile saline solution was injected into the left eye as a control. The animals were sacrificed after 2, 9, 14, or 28 days. The eyes were enucleated, and the vitreous was removed. The half-life of acyclovir was determined using high-performance liquid chromatography. Electroretinograms were recorded on days 2, 9, 14, and 28 in the eight animals that were sacrificed 28 days after injection according to a modified protocol of the International Society for Clinical Electrophysiology of Vision.RESULTS:Acyclovir rapidly decayed in the vitreous within the first two days after treatment and remained at low levels from day 9 onward. The eyes that were injected with acyclovir did not present any electroretinographic changes compared with the control eyes.CONCLUSIONS:The vitreous half-life of acyclovir is short, and the electrophysiological findings suggest that the intravitreal delivery of 1 mg acyclovir is safe and well tolerated by the rabbit retina.

Intravitreal injection of the synthetic peptide LyeTx I b, derived from a spider toxin, into the rabbit eye is safe and prevents neovascularization in a chorio-allantoic membrane model

“…At 28 days after the LyeTx I b intravitreal injection, no alterations were detected. The analysis of the b-wave amplitude variation according to the luminous stimulus intensity is a widely used method for the functional evaluation of the retina [ 21 , 22 ].…”

Noninvasive Electroretinography Assessment of Intravitreal Sustained-Release Methotrexate Microimplants in Rabbit Eyes

“…As reported in prior studies, the ratio of the B-wave amplitude to the A-wave amplitude, also known as the B/A ratio, is often used as an indicator of the retinal functional integrity. 10,11 The B/A ratio for each intensity was also recorded for both the PS and PE conditions. The mean values of all parameters for each intensity (A-wave amplitude, A-wave implicit time, B-wave amplitude, B-wave implicit time, and B/A ratio) were obtained for each time point (PE condition: days 5, 12, 19, and 33; n = 2 for each time point) for both scotopic and photopic protocols.…”

Estudo farmacológico, eletrofisiológico, imunocitoquímico e morfológico da injeção intravítrea de aciclovir em coelhos

“…Novos estudos com verificação de meia vida em menos de 48 h são necessários. 143,144 Este estudo apresenta algumas limitações. Os olhos de coelhos e humanos apresentam diferenças inerentes entre essas espécies.…”