Itraconazole (Page 5 of 9)

Effect of Other Drugs on Itraconazole Capsules

Itraconazole is mainly metabolized through CYP3A4. Other substances that either share this metabolic pathway or modify CYP3A4 activity may influence the pharmacokinetics of itraconazole. Some concomitant drugs have the potential to interact with itraconazole capsules resulting in either increased or sometimes decreased concentrations of itraconazole. Increased concentrations may increase the risk of adverse reactions associated with itraconazole capsules. Decreased concentrations may reduce itraconazole capsule efficacy.

Table 2 lists examples of drugs that may affect itraconazole concentrations, but is not a comprehensive list. Refer to the approved product labeling to become familiar with the interaction pathways, risk potential and specific actions to be taken with regards to each concomitant drug prior to initiating therapy with itraconazole capsules.

Although many of the clinical drug interactions in Table 2 are based on information with a similar azole antifungal, ketoconazole, these interactions are expected to occur with itraconazole capsules.

Table 2: Drug Interactions with Other Drugs that Affect Itraconazole Concentrations
*
Based on clinical drug interaction information with itraconazole.

Concomitant Drug Within Class

Prevention or Management

Drug Interactions with Other Drugs that Increase Itraconazole Concentrations and May Increase Risk of Adverse Reactions Associated with Itraconazole

Antibacterials

Ciprofloxacin *

Erythromycin *

Clarithromycin *

Monitor for adverse reactions. Itraconazole capsule dose reduction may be necessary.

Antineoplastics

Idelalisib

Monitor for adverse reactions. Itraconazole capsule dose reduction may be necessary. See also Table 1.

Antivirals

Cobicistat

Darunavir (ritonavir-boosted)

Elvitegravir (ritonavir-boosted)

Fosamprenavir (ritonavir-boosted)

Indinavir *

Ombitasvir/Paritaprevir/Ritonavir with or

without Dasabuvir

Ritonavir

Saquinavir

Monitor for adverse reactions. Itraconazole capsule dose reduction may be necessary. For cobicistat, elvitegravir, indinavir, ombitasvir/paritaprevir/ritonavir with or without dasabuvir, ritonavir, and saquinavir, see also Table 1.

Calcium Channel Blockers

Diltiazem

Monitor for adverse reactions. Itraconazole capsule dose reduction may be necessary. See also Table 1.

Drug Interactions with Other Drugs that Decrease Itraconazole Concentrations and May Reduce Efficacy of Itraconazole Capsules

Antibacterials

Isoniazid

Rifampicin *

Not recommended 2 weeks before and during itraconazole capsule treatment.

Rifabutin *

Not recommended 2 weeks before, during, and 2 weeks after itraconazole capsule treatment. See also Table 1.

Anticonvulsants

Phenobarbital

Phenytoin *

Not recommended 2 weeks before and during itraconazole capsule treatment.

Carbamazepine

Not recommended 2 weeks before, during, and 2 weeks after itraconazole capsule treatment. See also Table 1.

Antivirals

Efavirenz *

Nevirapine *

Not recommended 2 weeks before and during itraconazole capsule treatment.

Gastrointestinal Drugs

Drugs that reduce gastric acidity e.g., acid neutralizing medicines such as aluminum hydroxide, or acid secretion suppressors such as H2 -receptor antagonists and proton pump inhibitors.

Use with caution. Administer acid neutralizing medicines at least 2 hours before or 2 hours after the intake of itraconazole capsules.

Miscellaneous Drugs and Other Substances

Lumacaftor/Ivacaftor

Not recommended 2 weeks before, during, and 2 weeks after itraconazole capsule treatment.

Pediatric Population

Interaction studies have only been performed in adults.

Carcinogenesis, Mutagenesis, and Impairment of Fertility

Itraconazole showed no evidence of carcinogenicity potential in mice treated orally for 23 months at dosage levels up to 80 mg/kg/day (approximately 10 times the maximum recommended human dose [MRHD]). Male rats treated with 25 mg/kg/day (3.1 times the MRHD) had a slightly increased incidence of soft tissue sarcoma. These sarcomas may have been a consequence of hypercholesterolemia, which is a response of rats, but not dogs or humans, to chronic itraconazole administration. Female rats treated with 50 mg/kg/day (6.25 times the MRHD) had an increased incidence of squamous cell carcinoma of the lung (2/50) as compared to the untreated group. Although the occurrence of squamous cell carcinoma in the lung is extremely uncommon in untreated rats, the increase in this study was not statistically significant.

Itraconazole produced no mutagenic effects when assayed in DNA repair test (unscheduled DNA synthesis) in primary rat hepatocytes, in Ames tests with Salmonella typhimurium (6 strains) and Escherichia coli , in the mouse lymphoma gene mutation tests, in a sex-linked recessive lethal mutation (Drosophila melanogaster) test, in chromosome aberration tests in human lymphocytes, in a cell transformation test with C3H/10T½ C18 mouse embryo fibroblasts cells, in a dominant lethal mutation test in male and female mice, and in micronucleus tests in mice and rats.

Itraconazole did not affect the fertility of male or female rats treated orally with dosage levels of up to 40 mg/kg/day (5 times the MRHD), even though parental toxicity was present at this dosage level. More severe signs of parental toxicity, including death, were present in the next higher dosage level, 160 mg/kg/day (20 times the MRHD).

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