Formal topical drug interaction studies with tacrolimus ointment have not been conducted.
Tacrolimus is not metabolized in human skin, indicating that there is no potential for percutaneous interactions that could affect the metabolism of tacrolimus.
Systemically available tacrolimus is metabolized via the hepatic cytochrome P-450 3A4 (CYP3A4). Systemic exposure from topical application of tacrolimus ointment is low (<1 ng/mL) and is unlikely to be affected by concomitant use of substances known to be inhibitors of CYP3A4. However, the possibility of interactions cannot be ruled out and the concomitant systemic administration of known CYP3A4 inhibitors (eg, erythromycin, itraconazole, ketoconazole and diltiazem) in patients with widespread and/or erythrodermic disease should be done with caution.
A potential interaction between vaccination and application of Protopic has not been investigated. Because of the potential risk of vaccination failure, vaccination should be administered prior to commencement of treatment, or during a treatment-free interval with a period of 14 days between the last application of Protopic and the vaccination. In case of live attenuated vaccination, this period should be extended to 28 days or the use of alternative vaccines should be considered.