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Drug Interactions between dextromethorphan / quinidine and Di-Phen

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

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Interactions between your drugs

Major

quiNIDine dextromethorphan

Applies to: dextromethorphan / quinidine and dextromethorphan / quinidine

GENERALLY AVOID: Coadministration with potent CYP450 2D6 inhibitors (e.g., quinidine, terbinafine) may significantly increase the plasma concentrations of dextromethorphan in patients who are extensive metabolizers of this isoenzyme (approximately 93% of Caucasians and more than 98% of Asians and individuals of African descent). The proposed mechanism is inhibition of the CYP450 2D6-mediated O-demethylation of dextromethorphan. Studies in humans have shown an increase in systemic exposure of dextromethorphan of up to 43-fold when given concurrently with quinidine. Increased plasma concentrations increase the risk of dextromethorphan-related adverse effects (e.g., agitation, confusion, tremor, insomnia, diarrhea, and respiratory depression) and serotonin syndrome. However, this interaction has also been used clinically, with dextromethorphan in combination with quinidine indicated by some authorities for the treatment of pseudobulbar affect. Data evaluating the impact of this interaction in patients who are poor metabolizers of CYP450 2D6 are limited; most studies include extensive metabolizers of this isoenzyme. It is expected that poor metabolizers would have elevated dextromethorphan levels without concurrent quinidine

MANAGEMENT: The combination of dextromethorphan with potent CYP450 2D6 inhibitors should be generally avoided. Some manufacturers consider the concomitant use of dextromethorphan and selective serotonin reuptake inhibitors contraindicated. If use is considered necessary, the patient should be monitored for signs of dextromethorphan adverse effects (e.g., agitation, confusion, tremor, insomnia, diarrhea, and respiratory depression) and serotonin syndrome, and advised to notify their health care professional if these adverse effects develop or worsen. Dose reduction of dextromethorphan may also be required.

References

  1. Zhang Y, Britto MR, Valderhaug KL, Wedlund PJ, Smith RA "Dextromethorphan: enhancing its systemic availability by way of low-dose quinidine-mediated inhibition of cytochrome P4502D6." Clin Pharmacol Ther 51 (1992): 647-55
  2. Schadel M, Wu DA, Otton SV, Kalow W, Sellers EM "Pharmacokinetics of dextromethorphan and metabolites in humans: influence of the CYP2d6 phenotype and quinidine inhibition." J Clin Psychopharmacol 15 (1995): 263-9
  3. Capon DA, Bochner F, Kerry N, Mikus G, Danz C, Somogyi AA "The influence of CYP2d6 polymorphism and quinidine on the disposition and antitussive effect of dextromethorphan in humans." Clin Pharmacol Ther 60 (1996): 295-307
  4. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  5. Cerner Multum, Inc. "Australian Product Information." O 0
  6. "Product Information. Nuedexta (dextromethorphan-quinidine)." Avanir Pharmaceuticals, Inc (2010):
View all 6 references

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Moderate

quiNIDine phenytoin

Applies to: dextromethorphan / quinidine and Di-Phen (phenytoin)

MONITOR: Hydantoins may increase the CYP450 hepatic metabolism of quinidine. Serum quinidine levels and quinidine effectiveness may be decreased.

MANAGEMENT: Quinidine levels and effectiveness should be monitored frequently after a hydantoin is added to or deleted from the patient's regimen. An increase in quinidine dosage may be required. Patients should be advised to notify their physician if they experience increased irregular heartbeats or worsening of their symptoms.

References

  1. Urbano AM "Phenytoin-quinidine interactions in a patient with recurrent ventricular tachyarrhythmias." N Engl J Med 308 (1983): 225
  2. Data JL, Wilkinson GR, Nies AS "Interaction of quinidine with anticonvulsant drugs." N Engl J Med 294 (1976): 699-702
  3. Farringer JA, Beach CL, Robinson CA, Wooding-Scott R, Slaughter RL, Clementi WA "Quinidine and 3-hydroxyquinidine levels during initiation of anticonvulsant therapy after chronic anticonvulsant administration." Drug Intell Clin Pharm 19 (1985): 461

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Moderate

phenytoin dextromethorphan

Applies to: Di-Phen (phenytoin) and dextromethorphan / quinidine

MONITOR: Central nervous system- and/or respiratory-depressant effects may be additively or synergistically increased in patients taking multiple drugs that cause these effects, especially in elderly or debilitated patients. Sedation and impairment of attention, judgment, thinking, and psychomotor skills may increase.

MANAGEMENT: During concomitant use of these drugs, patients should be monitored for potentially excessive or prolonged CNS and respiratory depression. Cautious dosage titration may be required, particularly at treatment initiation. Ambulatory patients should be counseled to avoid hazardous activities requiring mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

References

  1. Hamilton MJ, Bush M, Smith P, Peck AW "The effects of bupropion, a new antidepressant drug, and diazepam, and their interaction in man." Br J Clin Pharmacol 14 (1982): 791-7
  2. Stambaugh JE, Lane C "Analgesic efficacy and pharmacokinetic evaluation of meperidine and hydroxyzine, alone and in combination." Cancer Invest 1 (1983): 111-7
  3. Sotaniemi EA, Anttila M, Rautio A, et al. "Propranolol and sotalol metabolism after a drinking party." Clin Pharmacol Ther 29 (1981): 705-10
  4. Grabowski BS, Cady WJ, Young WW, Emery JF "Effects of acute alcohol administration on propranolol absorption." Int J Clin Pharmacol Ther Toxicol 18 (1980): 317-9
  5. Lemberger L, Rowe H, Bosomworth JC, Tenbarge JB, Bergstrom RF "The effect of fluoxetine on the pharmacokinetics and psychomotor responses of diazepam." Clin Pharmacol Ther 43 (1988): 412-9
  6. MacLeod SM, Giles HG, Patzalek G, Thiessen JJ, Sellers EM "Diazepam actions and plasma concentrations following ethanol ingestion." Eur J Clin Pharmacol 11 (1977): 345-9
  7. Divoll M, Greenblatt DJ, Lacasse Y, Shader RI "Benzodiazepine overdosage: plasma concentrations and clinical outcome." Psychopharmacology (Berl) 73 (1981): 381-3
  8. Naylor GJ, McHarg A "Profound hypothermia on combined lithium carbonate and diazepam treatment." Br Med J 2 (1977): 22
  9. Stovner J, Endresen R "Intravenous anaesthesia with diazepam." Acta Anaesthesiol Scand 24 (1965): 223-7
  10. Driessen JJ, Vree TB, Booij LH, van der Pol FM, Crul JF "Effect of some benzodiazepines on peripheral neuromuscular function in the rat in-vitro hemidiaphragm preparation." J Pharm Pharmacol 36 (1984): 244-7
  11. Feldman SA, Crawley BE "Interaction of diazepam with the muscle-relaxant drugs." Br Med J 1 (1970): 336-8
  12. Ochs HR, Greenblatt DJ, Verburg-Ochs B "Propranolol interactions with diazepam, lorazepam and alprazolam." Clin Pharmacol Ther 36 (1984): 451-5
  13. Desager JP, Hulhoven R, Harvengt C, Hermann P, Guillet P, Thiercelin JF "Possible interactions between zolpidem, a new sleep inducer and chlorpromazine, a phenothiazine neuroleptic." Psychopharmacology (Berl) 96 (1988): 63-6
  14. Tverskoy M, Fleyshman G, Ezry J, Bradley EL, Jr Kissin I "Midazolam-morphine sedative interaction in patients." Anesth Analg 68 (1989): 282-5
  15. "Product Information. Iopidine (apraclonidine ophthalmic)." Alcon Laboratories Inc PROD
  16. Greiff JMC, Rowbotham D "Pharmacokinetic drug interactions with gastrointestinal motility modifying agents." Clin Pharmacokinet 27 (1994): 447-61
  17. Greb WH, Buscher G, Dierdorf HD, Koster FE, Wolf D, Mellows G "The effect of liver enzyme inhibition by cimetidine and enzyme induction by phenobarbitone on the pharmacokinetics of paroxetine." Acta Psychiatr Scand 80 Suppl (1989): 95-8
  18. Markowitz JS, Wells BG, Carson WH "Interactions between antipsychotic and antihypertensive drugs." Ann Pharmacother 29 (1995): 603-9
  19. "Product Information. Ultram (tramadol)." McNeil Pharmaceutical PROD (2001):
  20. "Product Information. Artane (trihexyphenidyl)." Lederle Laboratories PROD (2001):
  21. "Product Information. Ultiva (remifentanil)." Mylan Institutional (formally Bioniche Pharma USA Inc) PROD (2001):
  22. "Product Information. Seroquel (quetiapine)." Astra-Zeneca Pharmaceuticals PROD (2001):
  23. "Product Information. Meridia (sibutramine)." Knoll Pharmaceutical Company PROD (2001):
  24. "Product Information. Tasmar (tolcapone)." Valeant Pharmaceuticals PROD (2001):
  25. Miller LG "Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions." Arch Intern Med 158 (1998): 2200-11
  26. "Product Information. Precedex (dexmedetomidine)." Abbott Pharmaceutical PROD (2001):
  27. "Product Information. Trileptal (oxcarbazepine)." Novartis Pharmaceuticals PROD (2001):
  28. Ferslew KE, Hagardorn AN, McCormick WF "A fatal interaction of methocarbamol and ethanol in an accidental poisoning." J Forensic Sci 35 (1990): 477-82
  29. Plushner SL "Valerian: valeriana officinalis." Am J Health Syst Pharm 57 (2000): 328-35
  30. "Product Information. Xatral (alfuzosin)." Sanofi-Synthelabo Canada Inc (2002):
  31. "Product Information. Lexapro (escitalopram)." Forest Pharmaceuticals (2002):
  32. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  33. Cerner Multum, Inc. "Australian Product Information." O 0
  34. "Product Information. Fycompa (perampanel)." Eisai Inc (2012):
  35. "Product Information. Belsomra (suvorexant)." Merck & Co., Inc (2014):
  36. "Product Information. Rexulti (brexpiprazole)." Otsuka American Pharmaceuticals Inc (2015):
View all 36 references

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Drug and food interactions

Moderate

quiNIDine food

Applies to: dextromethorphan / 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

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

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Moderate

phenytoin food

Applies to: Di-Phen (phenytoin)

ADJUST DOSING INTERVAL: Phenytoin bioavailability may decrease to subtherapeutic levels when the suspension is given concomitantly with enteral feedings. The mechanism may be related to phenytoin binding to substances in the enteral formula (e.g., calcium, protein) and/or binding to the tube lumen. Data have been conflicting and some studies have reported no changes in phenytoin levels, while others have reported significant reductions.

MONITOR: Acute consumption of alcohol may increase plasma phenytoin levels. Chronic consumption of alcohol may decrease plasma phenytoin levels. The mechanism of this interaction is related to induction of phenytoin metabolism by ethanol during chronic administration. Other hydantoin derivatives may be similarly affected by ethanol.

MANAGEMENT: Some experts have recommended interrupting the feeding for 2 hours before and after the phenytoin dose, giving the phenytoin suspension diluted in water, and flushing the tube with water after administration; however, this method may not entirely avoid the interaction and is not always clinically feasible. Patients should be closely monitored for clinical and laboratory evidence of altered phenytoin efficacy and levels upon initiation and discontinuation of enteral feedings. Dosage adjustments or intravenous administration may be required until therapeutic serum levels are obtained. In addition, patients receiving phenytoin therapy should be warned about the interaction between phenytoin and ethanol and they should be advised to notify their physician if they experience worsening of seizure control or symptoms of toxicity, including drowsiness, visual disturbances, change in mental status, nausea, or ataxia.

References

  1. Sandor P, Sellers EM, Dumbrell M, Khouw V "Effect of short- and long-term alcohol use on phenytoin kinetics in chronic alcoholics." Clin Pharmacol Ther 30 (1981): 390-7
  2. Holtz L, Milton J, Sturek JK "Compatibility of medications with enteral feedings." JPEN J Parenter Enteral Nutr 11 (1987): 183-6
  3. Sellers EM, Holloway MR "Drug kinetics and alcohol ingestion." Clin Pharmacokinet 3 (1978): 440-52
  4. "Product Information. Dilantin (phenytoin)." Parke-Davis PROD (2001):
  5. Doak KK, Haas CE, Dunnigan KJ, et al. "Bioavailability of phenytoin acid and phenytoin sodium with enteral feedings." Pharmacotherapy 18 (1998): 637-45
  6. Rodman DP, Stevenson TL, Ray TR "Phenytoin malabsorption after jejunostomy tube delivery." Pharmacotherapy 15 (1995): 801-5
  7. Au Yeung SC, Ensom MH "Phenytoin and enteral feedings: does evidence support an interaction?" Ann Pharmacother 34 (2000): 896-905
  8. Ozuna J, Friel P "Effect of enteral tube feeding on serum phenytoin levels." J Neurosurg Nurs 16 (1984): 289-91
  9. Faraji B, Yu PP "Serum phenytoin levels of patients on gastrostomy tube feeding." J Neurosci Nurs 30 (1998): 55-9
  10. Marvel ME, Bertino JS "Comparative effects of an elemental and a complex enteral feeding formulation on the absorption of phenytoin suspension." JPEN J Parenter Enteral Nutr 15 (1991): 316-8
  11. Fleisher D, Sheth N, Kou JH "Phenytoin interaction with enteral feedings administered through nasogastric tubes." JPEN J Parenter Enteral Nutr 14 (1990): 513-6
  12. Haley CJ, Nelson J "Phenytoin-enteral feeding interaction." DICP 23 (1989): 796-8
  13. Guidry JR, Eastwood TF, Curry SC "Phenytoin absorption in volunteers receiving selected enteral feedings." West J Med 150 (1989): 659-61
  14. Krueger KA, Garnett WR, Comstock TJ, Fitzsimmons WE, Karnes HT, Pellock JM "Effect of two administration schedules of an enteral nutrient formula on phenytoin bioavailability." Epilepsia 28 (1987): 706-12
  15. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  16. Cerner Multum, Inc. "Australian Product Information." O 0
View all 16 references

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Moderate

dextromethorphan food

Applies to: dextromethorphan / quinidine

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

References

  1. Warrington SJ, Ankier SI, Turner P "Evaluation of possible interactions between ethanol and trazodone or amitriptyline." Neuropsychobiology 15 (1986): 31-7
  2. Gilman AG, eds., Nies AS, Rall TW, Taylor P "Goodman and Gilman's the Pharmacological Basis of Therapeutics." New York, NY: Pergamon Press Inc. (1990):
  3. "Product Information. Fycompa (perampanel)." Eisai Inc (2012):
  4. "Product Information. Rexulti (brexpiprazole)." Otsuka American Pharmaceuticals Inc (2015):
View all 4 references

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Therapeutic duplication warnings

Therapeutic duplication is the use of more than one medicine from the same drug category or therapeutic class to treat the same condition. This can be intentional in cases where drugs with similar actions are used together for demonstrated therapeutic benefit. It can also be unintentional in cases where a patient has been treated by more than one doctor, or had prescriptions filled at more than one pharmacy, and can have potentially adverse consequences.

Duplication

Antiarrhythmics

Therapeutic duplication

The recommended maximum number of medicines in the 'antiarrhythmics' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'antiarrhythmics' category:

  • dextromethorphan/quinidine
  • Di-Phen (phenytoin)

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.

Duplication

Group i antiarrhythmics

Therapeutic duplication

The recommended maximum number of medicines in the 'group I antiarrhythmics' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'group I antiarrhythmics' category:

  • dextromethorphan/quinidine
  • Di-Phen (phenytoin)

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.

See also

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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.

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