Introduction

Drugs are administered to the eye for local effects such as miosis, mydriasis, and anesthesia, or to reduce intraocular pressure in treating glaucoma. The ophthalmic formulation delivers the drug on the eye, into the eye, or onto the conjunctiva. Transcorneal transport (i.e., drug penetration into the eye) is not an effective process. It is estimated that only one-tenth of a dose penetrates into the eye.

Formulations used include aqueous solutions, aqueous suspensions, ointments, and inserts. Every ophthalmic product must be sterile in its final container to prevent microbial contamination of the eye. Preservatives are added to the formulation to maintain sterility once the container has been opened. Ophthalmic formulations also require that the pH, buffer capacity, viscosity, and tonicity of the formulation is carefully controlled.

ASHP has prepared a Technical Assistance Bulletin entitled, "Pharmacy-Prepared Ophthalmic Products." The bulletin gives a sketch of the many considerations that are inherent in compounding ophthalmic formulations. The bulletin then stresses the need for established policies and procedures. It states that all compounding must be performed in a laminar air flow hood, and gives some general information about how to filtration sterilize solutions. Ophthalmic suspensions and ointments cannot be filtration sterilized and must either be sterilized as a finished product, or have each component separately sterilized and then combined using aseptic techniques.