Page 1179 - Basic _ Clinical Pharmacology ( PDFDrive )

CHAPTER 66 Important Drug Interactions & Their Mechanisms 1165

TABLE 66–1 Important drug interactions.

Drug or Properties Promoting
Drug Group Drug Interaction Clinically Documented Interactions
Cyclosporine Statins: [NP] Decreased metabolism of atorvastatin, lovastatin, and simvastatin.
(cont.) Myopathy and rhabdomyolysis noted in patients taking statins and cyclosporine.
Drugs that may decrease cyclosporine effect:
Bosentan: [P] Increased cyclosporine elimination.
Dexamethasone: [NP] Increased cyclosporine metabolism.
Efavirenz: [P] Increased cyclosporine metabolism.
Etravirine: [NP] Increased cyclosporine metabolism.
Nevirapine: [NP] Increased cyclosporine metabolism.
Phenytoin: [P] Increased cyclosporine metabolism.
Rifabutin: [NP] Increased cyclosporine metabolism.
Rifampin: [P] Increased cyclosporine elimination.
St. John’s wort: [NP] Increased cyclosporine elimination.
See also Azole antifungals; Barbiturates; Calcium channel blockers; Carbamazepine.
Digitalis Digoxin susceptible to alteration of Drugs that may increase digitalis effect:
glycosides gastrointestinal absorption. Renal
and nonrenal excretion of digoxin Amiodarone: [P] Increased digoxin plasma concentrations. Expect similar interaction
susceptible to inhibition. Digitalis with dronedarone.
toxicity may be increased by drug- Antivirals: [P] Daclatasvir, indinavir, nelfinavir, paritaprevir, ritonavir, saquinavir, and
induced electrolyte imbalance telaprevir reduce the elimination of digoxin.
(eg, hypokalemia).
Conivaptan: [P] Increased digoxin plasma concentrations.
Cyclosporine: [P] Increased digoxin plasma concentrations.
Macrolide antibiotics: [P] Azithromycin, clarithromycin, and erythromycin inhibit the
elimination of digoxin.
Potassium-depleting drugs: [P] Increases likelihood of digitalis toxicity.
Propafenone: [P] Increases digoxin plasma concentrations.
Quinidine: [HP] Increased digoxin plasma concentrations; displaces digoxin from tissue
binding sites.
Spironolactone: [NE] Increased digoxin plasma concentrations.
Tacrolimus: [P] Increased digoxin plasma concentrations.
Ticagrelor: [P] Increased digoxin plasma concentrations.
See also Azole antifungals; Calcium channel blockers.
Drugs that may decrease digitalis effect:
Kaolin-pectin: [P] Decreased gastrointestinal digoxin absorption.
Rifampin: [NE] Increased metabolism of digitoxin and elimination of digoxin.
St. John’s wort: [NP] Increased digoxin elimination.
Sulfasalazine: [NE] Decreased gastrointestinal digoxin absorption.
See also Acid reducing agents; Bile acid-binding resins; Carbamazepine.
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.
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