Page 1185 - Basic _ Clinical Pharmacology ( PDFDrive )

CHAPTER 66 Important Drug Interactions & Their Mechanisms 1171

TABLE 66–1 Important drug interactions.

Drug or Properties Promoting
Drug Group Drug Interaction Clinically Documented Interactions
Potassium- Kinase inhibitors: [P] Decreased metabolism of eplerenone with ceritinib, dasatinib,
sparing diuret- imatinib, idelalisib, and lapatinib.
ics (amiloride,
eplerenone, Potassium-sparing diuretics: [P] Additive hyperkalemic effect.
spironolactone, Potassium supplements: [P] Additive hyperkalemic effect; especially a problem in
triamterene) presence of renal impairment.
(cont.)
See also Azole antifungals; Digitalis glycosides; Macrolides; Nonsteroidal anti-
inflammatory drugs.
Probenecid Interference with renal excretion Clofibrate: [P] Reduced glucuronide conjugation of clofibric acid.
of drugs that undergo active
tubular secretion, especially weak Methotrexate: [P] Decreased renal methotrexate excretion; possible methotrexate
acids. Inhibition of glucuronide toxicity.
conjugation of other drugs. Pralatrexate: [P] Decreased renal pralatrexate excretion; possible pralatrexate toxicity.
Penicillin: [P] Decreased renal penicillin excretion.
Salicylates: [P] Decreased uricosuric effect of probenecid (interaction unlikely with
less than 1.5 g of salicylate daily).
Quinidine Substrate of CYP3A4. Inhibits Acetazolamide: [P] Decreased renal quinidine excretion due to increased urinary pH;
CYP2D6. Renal excretion susceptible elevated serum quinidine.
to changes in urine pH. Additive
effects with other agents that Amiodarone: [NP] Increased serum quinidine levels; additive prolongation of QT c
prolong the QT c interval. interval.
Antivirals: [P] Amprenavir, atazanavir, boceprevir, darunavir, delavirdine,
fosamprenavir, indinavir, nelfinavir, ritonavir, saquinavir, simeprevir, and telaprevir
inhibit the metabolism of quinidine.
Boceprevir: [P] Decreased metabolism of quinidine.
Cobicistat: [P] Decreased metabolism of quinidine.
Conivaptan: [P] Decreased metabolism of quinidine.
Kaolin-pectin: [NE] Decreased gastrointestinal absorption of quinidine.
Kinase inhibitors: [P] Decreased metabolism of quinidine with ceritinib, dasatinib,
imatinib, idelalisib, and lapatinib.
Rifampin: [P] Increased quinidine metabolism.
Thioridazine: [NE] Decreased thioridazine metabolism; additive prolongation of QT c
interval.
See also Anticoagulants, oral; Antidepressants, tricyclic; Azole antifungals; Barbiturates;
Cimetidine; Digitalis glycosides; Macrolides; Phenytoin.
Quinolone Susceptible to inhibition of Caffeine: [P] Ciprofloxacin, enoxacin, and, to a lesser extent, norfloxacin inhibit caffeine
antibiotics gastrointestinal absorption. Some metabolism.
quinolones (ciprofloxacin, enoxacin)
inhibit CYP1A2, while ciprofloxacin Frovatriptan: [P] Ciprofloxacin, enoxacin, and, to a lesser extent, norfloxacin inhibit
also inhibits CYP3A4. frovatriptan metabolism.
Ropinirole: [P] Ciprofloxacin, enoxacin, and, to a lesser extent, norfloxacin inhibit
ropinirole metabolism.
Sucralfate: [HP] Reduced gastrointestinal absorption of ciprofloxacin, norfloxacin, and
probably other quinolones.
Theophylline: [P] Ciprofloxacin, enoxacin, and, to a lesser extent, norfloxacin inhibit
theophylline 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.
(continued )