Drug Interaction with Voriconazole

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Omeprazole (Prilosec) has a negative reaction with Voriconazole. I would assume

that the same negative reaction would happen with Nexium, as it is the next

generation of Prilosec. As the publication date of this study is January 15,

2008, your doctor will probably not have heard about it yet.

Joe

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Clin Infect Dis. 2008 Jan 15;46(2):201-11.

Voriconazole therapeutic drug monitoring in patients with invasive mycoses

improves efficacy and safety outcomes.

Pascual A, Calandra T, Bolay S, Buclin T, Bille J, Marchetti O.

Infectious Diseases Service, Centre Hospitalier Universitaire Vaudois and

University of Lausanne, Lausanne, Switzerland.

BACKGROUND: Voriconazole is the therapy of choice for aspergillosis and a new

treatment option for candidiasis. Liver disease, age, genetic polymorphism of

the cytochrome CYP2C19, and comedications influence voriconazole metabolism.

Large variations in voriconazole pharmacokinetics may be associated with

decreased efficacy or with toxicity. METHODS: This study was conducted to assess

the utility of measuring voriconazole blood levels with individualized dose

adjustments. RESULTS: A total of 181 measurements with high-pressure liquid

chromatography were performed during 2388 treatment days in 52 patients. A large

variability in voriconazole trough blood levels was observed, ranging from <or=1

mg/L (the minimum inhibitory concentration at which, for most fungal pathogens,

90% of isolates are susceptible) in 25% of cases to >5.5 mg/L (a level possibly

associated with toxicity) in 31% of cases. Lack of response to therapy was more

frequent in patients with voriconazole levels

<or=1 mg/L (6 [46%] of 13 patients, including 5 patients with aspergillosis, 4

of whom were treated orally with a median dosage of 6 mg/kg per day) than in

those with voriconazole levels >1 mg/L (15 [12%] of 39 patients; P=.02). Blood

levels >1 mg/L were reached after increasing the voriconazole dosage, with

complete resolution of infection in all 6 cases. Among 16 patients with

voriconazole trough blood levels >5.5 mg/L, 5 patients (31%) presented with an

encephalopathy, including 4 patients who were treated intravenously with a

median voriconazole dosage of 8 mg/kg per day, whereas none of the patients with

levels <or=5.5 mg/L presented with neurological toxicity (P=.002). Comedication

with omeprazole possibly contributed to voriconazole accumulation in 4 patients.

In all cases, discontinuation of therapy resulted in prompt and complete

neurological recovery. CONCLUSIONS: Voriconazole therapeutic drug monitoring

improves the efficacy and safety of therapy in severely ill

patients with invasive mycoses.

PMID: 18171251 [PubMed - in process]