Article
Efficacy of different preparations of Triamcinolone acetonide for intravitreal injection
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Authors
Published: | September 22, 2004 |
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Outline
Text
Objective
Intravitreal injection of triamcinolone acetonide has become increasingly popular for the treatment of a variety of intraocular disorders. The concentrations used range from 4 to 25mg/0,2ml. Three different preparations have been described so far: (A) Injection with preservative after sedimentation, or micro-filtration via (B) three-way valve or, (C) reverse flow.
Methods
Commercially available triamcinolone acetonide (Volon A) was processed according to the different preparation guidelines and the concentrate was transferred into a syringe for transportation. Each concentrate was loaded into a sterile tuberculin syringe prior to the injection into an eye-model. Concentrations of triamcinolone acetonide and benzalkonium chloride were assessed quantitatively and with high-pressure liquid chromatography (HPLC).
Results
The concentrations of triamcinolone acetonide in the transport syringes ranged in all preparations from 93±6,7% to 106±5,4% of the target concentration. Benzalkonium chloride was found in large amounts in (A), but not in (B) or (C). After injection into the eye-model, the concentration of triamcinolone acetonide was reduced to 15,4±14% of the target concentration with preparation (B) and 11,3±12% with preparation (C), respectively. Benzalkonium chloride was not detected. Following method (A) a concentration of 45,1±16,2% could be measured with large amounts of benzalkonium chloride. A significant portion of the crystalline drug was found on the inner wall of both syringes and cannulas.
Conclusions
The different methods of preparations (A-C) of triamcinolone acetonide crystals for intravitreal injection produce a high rate of retrieval for the active drug. After transfer into a sterile syringe a significant portion of the crystals gets lost. As a result, the final concentration of the steroid varies. Benzalkonium chloride augments the solubility of triamcinolone acetonide crystals. However, contamination with this preservative is not desired because of its assumed retinotoxic effect.