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Extemporaneous compounding

General principles involved in the extemporaneous compounding of ophthalmic preparations

This document Copyright © 2002 D.McAuley, GlobalRPh Inc. All Rights Reserved.

         There are several important factors to consider when called upon to compound a sterile ophthalmic preparation .  In many cases, the drugs involved have a narrow therapeutic range and even small errors when introduced have the potential to cause irreversible damage to the eye. Unfortunately, it is not difficult to locate court cases that have centered around  loss of sight of a patient due to a compounding error.  The following considerations are recommended whenever you prepare such  a product.
1 Ensure that there is adequate support in the literature for the product that is prescribed and that the requested concentration is within an acceptable range. Also make sure that there is not a suitable commercial product available that would eliminate the need to extemporaneously prepare a  product. The advent of new formulations in the past few years  has already drastically reduced the need for many previously compounded items.
2 Sterility of the final product is a must: strict adherence to aseptic technique as well as any other preventative measures must be in place.
3 The pH of the final product must be within an acceptable range.
4 Anticipated stability of the final product must be known, as well as the recommended storage requirements.
5 Adequate knowledge of  potential diluents or vehicles is required in order to ensure proper tonicity, viscosity, or dissolution of the final product.
6 Establishment of written procedures that fully document each step is an important consideration in order to reduce the likelihood of errors. Whenever  calculations are required, there should be a secondary source available to verify the accuracy. Also,  if multiple dilutions are needed,  it is recommended that a new syringe be used for each step in order to minimize the impact of residual contents. One should also use the smallest possible syringe  for each measurement in order to increase accuracy.
7 If the preparation of a product requires the breaking of an ampule or the reconstitution of a powder (e.g. cefazolin), it is recommended that the final product be filtered  prior to packaging in order to eliminate any particulate matter.
8 The preparation of intra-ocular products requires the use of preservative-free ingredients. Many preservatives have been found to be toxic to the inner ocular tissues.
9 Finally, before dispensing the finished product, always indicate the storage requirements, concentrations of ingredients, and the expected expiration date.
References:
1. American Society of Hospital Pharmacists, Inc.  ASHP technical assistance bulletin on pharmacy-prepared ophthalmic products.  Am J Hosp Pharm. 1993;  50:1462-3.
2. Reynolds LA,  Guidelines for preparation of sterile ophthalmic products.  Am J Hosp Pharm.  1991; 48:2438-9.
At a later date, I will be reviewing the various protocols and guidelines available in the literature regarding extemporaneously prepared ophthalmic products.  If you have any guidelines you would like to submit , please use the form  at the bottom of this page.
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