How can we make eye drops with voriconazole and what is the stability?

(Thanks to Apoth M. Doooms, Pharmacy, UZ GHB, Leuven)

The method of preparation can be taken from the article Stability of extemporaneously prepared voriconazole ophthalmic solution, published in Am J Health-Syst. Pharm (2009) 66, 1478-1483.

As a starting product we use Vfend 200 mg powder voear intravenous infusion (Pfizer). VFEND is a sterile lyophilisate with no preservatives for single use. Sodium Sulfobutylether beta-cyclodextrin (SBECD) ensures that voriconazole is in solution.

The producer gives the following modifications for the use of this gelyofilized powder. The powder is reconstituted with 19 ml of water for injection, so that an extractable volume of 20 ml of clear concentrate is obtained with 10 mg/ml of voriconazole. From a microbiological point of view, once reconstituted, the product should be used immediately. When the product is not used immediately, the user is responsible for the storage time during use and the storage conditions prior to use. The storage period shall not exceed 24 hours at 2 °C to 8 °C unless reconstitution has been carried out under controlled and validated aseptic conditions. The chemical and physical stability during use has been demonstrated for 24 hours at a temperature of 2 °C to 8 °C. Discard the VFEND vial if the vacuum does not pull the diluent into the vial. It is recommended to use a standard (non-automatic) 20 ml syringe to ensure that the exact amount (19.0 ml) of water for injection is used. This medicinal product is intended for single use only and any unused solution should be destroyed. Only clear solutions without powder particles can be used. For the preparation of 2% eye drops is used as solvent 9ml water for injections, which contains 0.01% Benzalkonium chloride. For the 1% solution This is 19 ml water for injections with 0.01% benzalkonium. Sterilization can be done by filtration on a sterilized 0.2 micrometer filter in a pre-sterilized zentropvial. Stored at room temperature, the shelf life of the non-attached vial for the 2% solution is 16 weeks but the 1% solution can be stored in the refrigerator for 14 weeks.