Voriconazole (Vfend), as a broad-spectrum triazole antifungal drug, its efficacy and drug interactions involve the regulation of the CYP450 metabolic system. It is important to pay attention to its synergistic or antagonistic effects with other drugs, especially the risk of changes in blood drug concentration when used in combination with CYP3A4/CYP2C19 substrates.

1. Effect of action

(1) Antibacterial spectrum

It has strong inhibitory effects on Aspergillus, Candida (including fluconazole resistant strains), Fusarium, etc., but is ineffective against commensal bacteria.

(2) Mechanism of action

By inhibiting the CYP450 dependent 14 α - demethylase involved in ergosterol synthesis on fungal cell membranes, membrane permeability changes and sterilization occurs.

(3) Pharmacokinetic characteristics

Oral bioavailability is 96%, protein binding rate is 58%, metabolized by CYP2C19/CYP3A4/CYP2C9, with a half-life of 6-9 hours.

2. Drug interactions

(1) Taboo of enzyme inducers

The combination of strong CYP450 inducers such as rifampicin, carbamazepine, and phenobarbital is prohibited, which can cause a 90% decrease in the blood concentration of voriconazole.

(2) Enzyme inhibitor risk

The combination of clarithromycin and erythromycin can increase the AUC of voriconazole by 57%, and liver toxicity needs to be monitored.

(3) The impact of substrate drugs

Increase the blood concentration of cyclosporine and tacrolimus by 2-3 times, and when used in combination, reduce the dosage by 50% and monitor the blood concentration.

(4) Special interactions

When combined with omeprazole, the dosage of the latter needs to be halved; Combined use with phenytoin requires doubling the dose of voriconazole.