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Abstract
Topical preparations represent a large percentage of compounded prescriptions, particularly in the area of dermatology. Properties of ointment bases vary greatly, and active ingredients are frequently added as aqueous or alcoholic solutions. Currently, there are no quantitative guidelines stating the various water and alcohol absorption capacity of different bases. A short experiment was designed to quantitate the amount of water or alcohol that could be absorbed by a series of ointment bases of varying types. Our findings may be used to assist compounding pharmacists in deciding what base is most suitable to use when considering the amount of water, alcohol, or any similar solvent needed to compound the preparation. A general overview of issues related to topical medication compounding is also provided in this article.
Need for Compounded Topical Preparations
There are many reasons why physicians request compounded prescriptions. A patient riiay need a médication in a different strength or a dosage form that is not commercially available. Others could require medication that is free of preservatives due to an allergy.1 The reason also may not be purely patient dependent. For example, the drug or à compound may be chemically or physically unstable, requiring preparation just prior to dispensing. Regardless of the reason, the flexibility offered by compounding allows physician-pharmacist teams the ability to tailor drug therapy to the specific and unique needs of the patient. This flexibility is of particular importance with dermatológica! preparations, where the vehicle used can be of critical importance to the successful delivery of drag.2'5 Additionally, combination preparations are frequently prescribed by dermatologists in order to improve application convenience to the patient and to limit cost to the patient by avoiding the need of multiple products.2
Estimates of the amount of extemporaneous compounding that occur in the U.S. vary greatly, with the estimated number of prescriptions written for extemporaneous compounds ranging from 30 to 250 million per year. Whatever the exact number may be, compounded prescription orders have been increasing since the early 1980s. Dermatologists, out of all the medical specialties, are among those who most frequently prescribe compounded prescriptions. As long as the need exists, compounding will remain an essential service that only pharmacists can provide.4"6
In many cases, the prescriber depends on the pharmacist's knowledge...