Evaluation of different preparation methods for a preservative free triamcinolone acetonide preparation for intravitreal administration: a validated stability indicating HPLC-method.

Intravitreally applied triamcinolone acetonide (TA) is used to treat a variety of macular diseases. Commercially available products of TA are mainly intended for intramuscular application and contain benzyl alcohol (BA) as a bacteriostatic preservative. Since this agent damages ocular tissues, different methods such as filtration techniques and centrifugation are usually used to eliminate BA from commercial products (40 mg/mL TA, 9.9 mg/mL BA). In this study, we evaluated these methods in regard to their ability to eliminate benzyl alcohol and to guarantee standard doses of triamcinolone acetonide. A new formulation without BA (TA 40 mg/mL) was developped according to the following criteria: autoclavability, stability, and suitability for intravitreal use. For QA/QC evaluation a new rapid and simple HPLC procedure (C18 RP column, mobile phase consisting of methanol-water, 48:52, v/v) to quantify the respective compounds was developed and validated according to ICH guidelines. The HPLC method was proven to be selective, linear, precise and accurate. Analysis of preparations based on commercial products undergoing different filtration techniques showed variable results: TA concentrations of 22-80% of the declared amount were found, and BA content was not reduced to safe levels (up to 39% of initial content remained). Centrifugation methods decreased the concentration of the preservative adequately, however agglomerated TA crystals were observed, leading to irreproducible and deviating particle sizes that are potentially harmful with ocular use. The newly developed preservative free formulation (TA 40 mg/mL) delivered uniform doses of TA, revealed no drug loss during forced light exposure and was proven to be stable, sterile and bacterial endotoxin free after autoclaving and after storage for three months,. The new formulation may offer an alternative for the in-house production of intravitreally applicable TA preparations in hospital pharmacies and should enhance medication safety.