OBJECT DRUGS

• Digoxin (Lanoxin, etc.)

PRECIPITANT DRUGS

P-glycoprotein Inducers:

• Carbamazepine (Tegretol, etc.)
• Dexamethasone (Decadron, etc.)
• Rifampin (Rimactane, etc.)
• St. John's wort
• Tipranavir (Aptivus)

Comment:

Rifampin and St. John's wort have been shown to substantially reduce the plasma concentration of digoxin; although data are limited, other P-glycoprotein inducers may have a similar effect on digoxin concentrations. Although some evidence suggests that carbamazepine induces P-gp, one study found no effect of carbamazepine on digoxin serum concentrations. Several days to weeks may be required to see the full effect a P-glycoprotein inducer on digoxin.

Class 3: Assess Risk & Take Action if Necessary

• Monitor: Monitor for altered digoxin effect if a P-glycoprotein inducer is initiated, discontinued or changed in dosage; adjustments of digoxin dosage may be needed.