Drug Interaction Report

CONTRAINDICATED: The administration of live smallpox virus vaccine during immunosuppressant or intense antineoplastic therapy may be associated with a risk of disseminated infection due to enhanced replication of vaccine virus in the presence of diminished immune competence. Patients may be immunosuppressed if they have recently received or are receiving alkylating agents, antimetabolites, radiation, some antirheumatic agents, high dosages of corticosteroids or adrenocorticotropic agents, or long-term topical or inhaled corticosteroids. These patients may also have increased adverse reactions and decreased or suboptimal immunologic response to vaccines. Cases of generalized vaccinia and progressive vaccinia have been reported in HIV patients who received the smallpox vaccine.

MANAGEMENT: Routine, nonemergency smallpox vaccination is contraindicated in patients receiving immunosuppressive therapy or cancer chemotherapy. Vaccination should be deferred until after such therapy is discontinued for at least 3 months in most cases. A longer waiting period may be necessary following treatment with agents that have a prolonged elimination half-life (e.g., leflunomide, teriflunomide). In patients who have recently been vaccinated, such therapy should not be initiated for at least 2 weeks (may be longer in some cases; refer to individual product labeling). Household contacts of immunosuppressed patients should also not be vaccinated. However, there are no absolute contraindications to vaccination if a high-risk exposure has occurred. In an outbreak emergency, smallpox vaccine is recommended for all persons, regardless of medical conditions. The risk for experiencing serious complications from the vaccine should be weighed against the risk of acquiring a potentially fatal smallpox infection.

ADJUST DOSING INTERVAL: Consumption of food has led to a 27% decrease in the bioavailability of orally administered tacrolimus.

MANAGEMENT: Tacrolimus should be administered at least one hour before or two hours after meals.

GENERALLY AVOID: Grapefruit juice has been reported to increase tacrolimus trough concentrations. Data are limited, but inhibition of the CYP450 enzyme system appears to be involved.

MANAGEMENT: The clinician may want to recommend that the patient avoid ingesting large amounts of grapefruit juice while taking tacrolimus.