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Drug Interactions between carvedilol and Quinidex Extentabs

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

quiNIDine carvedilol

Applies to: Quinidex Extentabs (quinidine) and carvedilol

MONITOR: Quinidine may increase serum levels of some oral beta-blockers. The proposed mechanism is inhibition of CYP450 2D6 first-pass metabolism and decreased hepatic clearance of hepatically metabolized beta-blockers. Quinidine and beta-blockers may also have additive negative inotropic effects, which can be beneficial when used to treat atrial fibrillation. However, adverse effects have been reported with quinidine and propranolol.

MANAGEMENT: Patients should be monitored for orthostatic hypotension, cardiac arrhythmias, bradycardia, and heart failure, and beta-blocker dosage should be decreased if necessary.

References (11)
  1. Manolis AS, Estes NA (1987) "Orthostatic hypotension due to quinidine and atenolol." Am J Med, 82, p. 1083-4
  2. Kessler KM, Humphries WC, Black M, Spann JF (1978) "Quinidine pharmacokinetics in patients with cirrhosis or receiving propranolol." Am Heart J, 96, p. 627-35
  3. Loon NR, Wilcox CS, Folger W (1986) "Orthostatic hypotension due to quinidine and propranolol." Am J Med, 81, p. 1101-4
  4. Zhou HH, Wood AJ (1990) "Differences in stereoselective disposition of propranolol do not explain sensitivity differences between white and Chinese subjects: correlation between the clearance of (-)- and (+)- propranolol." Clin Pharmacol Ther, 47, p. 719-23
  5. Dinai Y, Sharir M, Floman NN, Halkin H (1985) "Bradycardia induced by interaction between quinidine and ophthalmic timolol." Ann Intern Med, 103, p. 890-1
  6. Fenster P, Perrier D, Mayersohn M, Marcus FI (1980) "Kinetic evaluation of the propranolol-quinidine combination." Clin Pharmacol Ther, 27, p. 450-3
  7. Zhou HH, Anthony LB, Roden DM, Wood AJ (1990) "Quinidine reduces clearance of (+)-propranolol more than (-)-propranolol through marked reduction in 4-hydroxylation." Clin Pharmacol Ther, 47, p. 686-93
  8. Ochs HR, Greenblatt DJ, Woo E, et al. (1978) "Effect of propranolol on pharmacokinetics and acute electrocardiographic changes following intravenous quinidine in humans." Pharmacology, 17, p. 301-6
  9. Leemann T, Dayer P, Meyer UA (1986) "Single-dose quinidine treatment inhibits metoprolol oxidation in extensive metabolizers." Eur J Clin Pharmacol, 29, p. 739-41
  10. Dorian P, Newman D, Berman N, Hardy J, Mitchell J (1993) "Sotalol and type IA drugs in combination prevent recurrence of sustained ventricular tachycardia." J Am Coll Cardiol, 22, p. 106-13
  11. Edeki TI, He H, Wood AJ (1995) "Pharmacogenetic explanation for excessive B-blockade following timolol eye drops." JAMA, 274, p. 1611-3

Drug and food interactions

Moderate

quiNIDine food

Applies to: Quinidex Extentabs (quinidine)

GENERALLY AVOID: In a small, randomized, crossover study, the administration of quinidine with grapefruit juice (compared to water) to healthy volunteers significantly prolonged the time to reach peak plasma quinidine concentrations and decreased the plasma concentrations of its major metabolite, 3-hydroxyquinidine. These changes were associated pharmacodynamically with both a delay and a reduction in the maximal effect on QTc interval. The proposed mechanism is delay of gastric emptying as well as inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits.

MANAGEMENT: Given the drug's narrow therapeutic index, patients receiving quinidine therapy should avoid the consumption of grapefruits and grapefruit juice to prevent any undue fluctuations in plasma drug levels.

References (4)
  1. Ace LN, Jaffe JM, Kunka RL (1983) "Effect of food and an antacid on quinidine bioavailability." Biopharm Drug Dispos, 4, p. 183-90
  2. Min DI, Ku YM, Geraets DR, Lee HC (1996) "Effect of grapefruit juice on the pharmacokinetics and pharmacodynamics of quinidine in healthy volunteers." J Clin Pharmacol, 36, p. 469-76
  3. Ha HR, Chen J, Leuenberger PM, Freiburghaus AU, Follah F (1995) "In vitro inhibition of midazolam and quinidine metabolism by flavonoids." Eur J Clin Pharmacol, 48, p. 367-71
  4. Bailey DG, Dresser GR, Kreeft JH, Munoz C, Freeman DJ, Bend JR (2000) "Grapefruit-felodipine interaction: Effect of unprocessed fruit and probable active ingredients." Clin Pharmacol Ther, 68, p. 468-77

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

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