Abstract
Purpose:
The goal of this study was to determine if orally administered acetazolamide, a carbonic anhydrase inhibitor, penetrates the vitreous humor in humans. Carbonic anhydrase inhibitors are thought to modulate the polarized distribution of carbonic anhydrase at the level of the retinal pigment epithelium via extracellular pH gradients, and enhance fluid absorption from the retina. If orally administered acetazolamide penetrates the vitreous, a quantification study of vitreous concentrations of the drug could help establish safe dosages for intravitreous injection of the drug to treat diabetic macular edema.
Methods:
This was a prospective, non-randomized interventional case series of eyes that underwent pars plana vitrectomy for tractional retinal detachment repair. All patients except one control were given 500 mg of oral acetazolamide to take the night prior to surgery and upon awakening the morning of surgery (approximately 3 hours prior to surgery). During surgery, prior to beginning vitrectomy, 0.3 mL of vitreous fluid was obtained by clamping the infusion line and attaching the vitrector to a syringe via a short length of tubing. Vitreous samples were packed on ice and brought to the laboratory for analysis. Vitreous study specimens were extracted with acetonitrile, centrifuged to remove proteins and analyzed using a tandem mass spectrometer equipped with a high performance liquid chromatographer.
Results:
All 11 patients who took oral acetazolamide had detectable concentrations of acetazolamide in the vitreous. The control sample had no drug in the vitreous. Six specimens had acetazolamide in the 100-400 microgram/mL range, 2 specimens had acetazolamide in the 50-100 microgram/mL range and 3 specimens were measured under 1 microgram/mL.
Conclusions:
Orally administered acetazolamide penetrates the vitreous in humans. This study paves the way for additional research investigating intravitreous injection of carbonic anhydrase inhibitors and pharmacotherapeautics for diabetic macular edema.
Keywords: 688 retina •
499 diabetic retinopathy