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Drug Interactions between amitriptyline and dofetilide

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

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Interactions between your drugs

Major

amitriptyline dofetilide

Applies to: amitriptyline and dofetilide

GENERALLY AVOID: Like other class III antiarrhythmic agents, dofetilide can cause dose-related QT interval prolongation. Theoretically, coadministration with other agents that can prolong the QT interval may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. In general, the risk of an individual agent or a combination of agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia). In addition, the extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s).

MANAGEMENT: Coadministration of dofetilide with other drugs that can prolong the QT interval has not been studied and is not recommended.

References

  1. (2001) "Product Information. Tikosyn (dofetilide)." Pfizer U.S. Pharmaceuticals
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  3. Canadian Pharmacists Association (2006) e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink
  4. Cerner Multum, Inc. "Australian Product Information."
View all 4 references

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Drug and food interactions

Moderate

amitriptyline food

Applies to: amitriptyline

GENERALLY AVOID: Concomitant use of ethanol and a tricyclic antidepressant (TCA) may result altered TCA plasma levels and efficacy, and additive impairment of motor skills, especially driving skills. Acute ethanol ingestion may inhibit TCA metabolism, while chronic ingestion of large amounts of ethanol may induce hepatic TCA metabolism.

MANAGEMENT: Patients should be advised to avoid alcohol during TCA therapy. Alcoholics who have undergone detoxification should be monitored for decreased TCA efficacy. Dosage adjustments may be required.

References

  1. Dorian P, Sellers EM, Reed KL, et al. (1983) "Amitriptyline and ethanol: pharmacokinetic and pharmacodynamic interaction." Eur J Clin Pharmacol, 25, p. 325-31
  2. Warrington SJ, Ankier SI, Turner P (1986) "Evaluation of possible interactions between ethanol and trazodone or amitriptyline." Neuropsychobiology, 15, p. 31-7
  3. Sandoz M, Vandel S, Vandel B, Bonin B, Allers G, Volmat R (1983) "Biotransformation of amitriptyline in alcoholic depressive patients." Eur J Clin Pharmacol, 24, p. 615-21
  4. Ciraulo DA, Barnhill JG, Jaffe JH (1988) "Clinical pharmacokinetics of imipramine and desipramine in alcoholics and normal volunteers." Clin Pharmacol Ther, 43, p. 509-18
  5. Seppala T, Linnoila M, Elonen E, Mattila MJ, Makl M (1975) "Effect of tricyclic antidepressants and alcohol on psychomotor skills related to driving." Clin Pharmacol Ther, 17, p. 515-22
  6. Ciraulo DA, Barnhill JG, Jaffe JH, Ciraulo AM, Tarmey MF (1990) "Intravenous pharmacokinetics of 2-hydroxyimipramine in alcoholics and normal controls." J Stud Alcohol, 51, p. 366-72
  7. Ciraulo DA, Alderson LM, Chapron DJ, Jaffe JH, Subbarao B, Kramer PA (1982) "Imipramine disposition in alcoholics." J Clin Psychopharmacol, 2, p. 2-7
View all 7 references

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Minor

dofetilide food

Applies to: dofetilide

In vitro data suggest that grapefruit juice may inhibit the CYP450 3A4 first-pass metabolism of dofetilide. Decreased first-pass metabolism may increase dofetilide concentrations and increase the risk of QT interval prolongation and arrhythmias. The clinical significance is unknown, since dofetilide has a high oral bioavailability and a low affinity for CYP450 3A4. The manufacturer recommends caution.

References

  1. (2001) "Product Information. Tikosyn (dofetilide)." Pfizer U.S. Pharmaceuticals

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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

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.