Buffering capacity of bovine vitreous.
OBJECTIVE
To measure the buffering capacity of bovine vitreous to HCl, NaOH, and triamcinolone acetonide.


METHODS
Vitreous was dissected from 10 bovine globes, homogenized, and divided into 5.0-mL aliquots. The carbonate/bicarbonate buffer of the vitreous was maintained by performing all subsequent titrations under an atmosphere of 5% CO2/95% air. The pH was monitored during the addition of 0.1 N HCl, 0.1 N NaOH, or 40 mg/mL triamcinolone acetonide to the vitreous sample; 0.9% NaCl was used as control.


RESULTS
The buffering capacity of bovine vitreous to HCl was 10 times greater than that of 0.9% NaCl. The buffering capacity of vitreous to NaOH was four times greater than that of 0.9% NaCl. Bovine vitreous was able to resist pH changes from addition of triamcinolone acetonide at levels 20 times greater than commonly injected intravitreally.


CONCLUSIONS
Vitreous had a greater buffering capacity than 0.9% NaCl, indicating a greater capacity to remain stable when acidic or alkaline pharmaceuticals are injected in microliter amounts.
Conway
Mandi D
MD
Department of Ophthalmology, Tulane University Health Sciences Center, New Orleans, Louisiana, USA. ccole@eyes.arizona.edu
Jermak
Christopher M
CM
Peyman
Gholam A
GA
Swanson
Harvey T
HT
Blake
Diane A
DA
D000818:Animals; D002021:Buffers; D002417:Cattle; D006851:Hydrochloric Acid / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D012972:Sodium Hydroxide / Q000737:chemistry; D014222:Triamcinolone Acetonide / Q000737:chemistry; D014822:Vitreous Body / Q000737:chemistry*
D002021:Buffers; D012972:Sodium Hydroxide; D014222:Triamcinolone Acetonide; D006851:Hydrochloric Acid