CHICAGO (Reuters Health) - Physicians, nurses and other health care providers should be aware that patients receiving intravenous treatment with the antifungal drug voriconazole may develop a range of neurological side effects, including auditory and visual hallucinations, according to a report presented at the 47th annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
Voriconazole, sold under the trade name Vfend, is a relatively new drug used to treat serious fungus infections, such as invasive mold infections and invasive candidiasis. Many of these patients are extremely ill and are receiving several different drugs, which makes it difficult to distinguish the side effects of specific drugs from the symptoms of the underlying illness.
To estimate the frequency and seriousness of voriconazole side effects, Dr. Dimitrios Zonios and colleagues at the National Institutes of Health in Bethesda, Maryland, evaluated patients in an ongoing prospective study that was assessing voriconazole toxicity. The researchers focused on side effects of the central nervous system, which are not well characterized for the drug.
Between March 2006 and June 2007, the researchers evaluated 66 cancer patients who were being treated with intravenous voriconazole at their institution. Careful interviews and toxicity evaluations were conducted for each patient.
Zonios’s group identified eight patients who experienced hallucinations. All of these patients had visual hallucinations and four also had auditory hallucinations. In six patients the hallucinations began within 24 hours of receiving the drug, and after 1 and 2 weeks of treatment in the other two patients.
The hallucinations quickly disappeared after the drug was stopped in six patients and after the dosage was reduced in the other two. No residual effects were noted.
The visual hallucinations frequently consisted of seeing people or scenes. One patient reported seeing flying objects, another saw scenes of Montana and New York City, and a third patient saw a giant “Wookie” from the movie Star Wars bending over his bed.
The auditory hallucinations often consisted of hearing voices and music, and one patient reported hearing TV commercials.
All of the patients remained oriented, alert, and understood that the hallucinations were not real.
The researchers were not able to identify any other drugs that were likely to have caused the hallucinations and none of the other drugs interacted voriconazole to cause an increase in blood levels of the antifungal drug. Drug levels were within the dose recommendations in all eight patients when symptoms began.
Other neurological effects seen in the group as a whole included visual disturbances, such as blurry vision, in 15 patients; sensitivity to light in 10; and a decreased ability to concentrate in 2 patients. Another 5 developed signs of liver damage.
Zonios and colleagues conclude that visual and auditory hallucinations are “not uncommon” side effects of voriconazole and suggest that health care professionals offer reassurance to patients, should this complication occur.
The possible association between voriconazole-related hallucinations and high blood levels of the drug is currently being investigated, the investigators added.