E, Expected; HP, Highly predictable. Interaction occurs in almost all patients receiving the interacting combination; P, Predictable. Interaction occurs in most patients receiving the combination; NP, Not predictable. Interaction occurs only in some patients receiving the combination; NE, Not established. Insufficient data available on which to base estimate of predictability.
TABLE 66–1 Important drug interactions.
Acetaminophen: [NE] Decreased gastrointestinal absorption of acetaminophen.
Digitalis glycosides: [NE] Decreased gastrointestinal absorption of digitoxin (possibly also digoxin). Furosemide: [P] Decreased gastrointestinal absorption of furosemide. Methotrexate: [NE] Reduced gastrointestinal absorption of methotrexate. Mycophenolate: [P] Reduced gastrointestinal absorption of mycophenolate. Thiazide diuretics: [P] Reduced gastrointestinal absorption of thiazides. Thyroid hormones: [P] Reduced thyroid absorption. See also Anticoagulants, oral.
E, Expected; HP, Highly predictable. Interaction occurs in almost all patients receiving the interacting combination; P, Predictable. Interaction occurs in most patients receiving the combination; NP, Not predictable. Interaction occurs only in some patients receiving the combination; NE, Not established. Insufficient data available on which to base estimate of predictability.
TABLE 66–1 Important drug interactions.
Carbamazepine Induction of hepatic microsomal drug-metabolizing enzymes and P-glycoprotein. Susceptible to induction and inhibition of metabolism, primarily by CYP3A4.
Amiodarone: [P] Decreased metabolism of carbamazepine; increased metabolism of amiodarone. Expect similar interactions with dronedarone. Antivirals: [P] Amprenavir, atazanavir, boceprevir, darunavir, delavirdine, fosamprenavir, indinavir, nelfinavir, ritonavir, saquinavir, simeprevir, and telaprevir inhibit the metabolism of carbamazepine. Increased metabolism of antivirals by carbamazepine.
Cimetidine: [P] Decreased carbamazepine metabolism. Corticosteroids: [P] Increased corticosteroid metabolism. Cyclosporine: [P] Increased cyclosporine metabolism and possible decreased carbamazepine metabolism. Danazol: [P] Decreased carbamazepine metabolism. Digitalis glycosides: [P] Increased digoxin elimination. Fluvoxamine: [NE] Decreased carbamazepine metabolism. Estrogens: [P] Increased estrogen metabolism.
E, Expected; HP, Highly predictable. Interaction occurs in almost all patients receiving the interacting combination; P, Predictable. Interaction occurs in most patients receiving the combination; NP, Not predictable. Interaction occurs only in some patients receiving the combination; NE, Not established. Insufficient data available on which to base estimate of predictability.
TABLE 66–1 Important drug interactions.
Carbamazepine (cont.)
Cimetidine Inhibits hepatic microsomal drug-metabolizing enzymes. (Ranitidine, famotidine, and nizatidine do not.) May inhibit the renal tubular secretion of weak bases.
Cisapride Susceptible to induction and inhibition of metabolism by CYP3A4 inhibitors. High cisapride serum concentrations can result in ventricular arrhythmias.