Liquid in fish oil capsules interacts with foam plastic cups


A nurse caring for a patient who was unable to swallow LOVAZA (omega-3-acid ethyl esters), punched holes in the large, soft gelatin capsule, squeezed the oily yellow liquid contents into a disposable foam plastic cup (often called a Styrofoam cup), and diluted it with cranberry juice. Later, as the patient raised the cup to drink the juice, the cup began to leak.

The product information has no warnings regarding the need to swallow the capsules whole or avoid contact with foam plastic cups. Further investigation found no mention of this issue in the medical literature, however, an Internet search of “omega 3” (fish oil) and “Styrofoam” drew a number of hits, including a You Tube video demonstrating the action of nonprescription omega-3 products on foam plastic cups.

In a test done by us, the walls of a foam plastic cup containing liquid from a Lovaza capsule began to dissolve within a minute; the bottom of the cup dissolved after 10 minutes. Other liquid capsule products such as vitamin E did not appear to affect the cup.

It is not known whether it is the omega-3-acid or some other component of the liquid that is causing this reaction. The effect upon other types of plastic (e.g., special plastic syringes used for oral liquids) and potential toxicity from dissolved plasticizers is also unknown but clearly needs to be investigated by companies that provide omega-3-acid products so information can be added to labeling.

Until more is known, we’ve mentioned to the Lovaza manufacturer GlaxoSmithKline that, at a minimum, the label needs to warn about contact with plastics. If you need to mix the product in fluids before swallowing, we recommend that you use a small glass.

Incidentally, “Styrofoam” is a Dow Chemical Company trademark for a different plastic than foam used in cups.

Created on April 23, 2009

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