Why do some drugs need a micron filter? What is it filtering out? What harm could be caused by not using a filter?

—P. Manfresca, BSN

Filters for intravenous (IV) medication administration are used to remove contaminants from intravenous products. This filtration is intended to protect the patient receiving the medication by filtering out particulate matter, bacteria, and air emboli, protecting the patient from phlebitis due to particulates or infection due to bacteria.

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Filters are used with the intravenous administration of many medications. These filters may be contained within an IV line (in-line filter), and are available in a variety of sizes. A 5-micron filter removes large particles that may have been introduced during product preparation, such as glass particles from glass ampules. The 0.22-micron filter is one of the smallest used in patient care, and removes bacteria. There are not currently filters that remove viruses.

Not all intravenous medications should be administered through a filter, and others may require filters of a specific size. The molecules of some medications may be too large to pass through a filter, or may otherwise bind to the filter and be removed. Thus, it is important to consult your institution’s policies for details on which medications require a filter for parenteral administration.