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Drug Interactions between methadone and mifepristone

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

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Interactions between your drugs

Major

methadone miFEPRIStone

Applies to: methadone and mifepristone

GENERALLY AVOID: Mifepristone may prolong the QTc interval in a dose-related manner. 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. Mifepristone and its metabolites have been found to inhibit the hERG-encoded cardiac potassium channels responsible for the rapid delayed rectifier K+ (IKr) repolarizing current. However, there is little or no experience with high exposure, concomitant dosing with other QT-prolonging drugs, or potassium channel variants resulting in a long QT interval. 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). Since mifepristone can commonly cause hypokalemia during prolonged use, this should also be considered during coadministration with other QT-prolonging drugs. In a study of patients with Cushing's syndrome, hypokalemia was observed in 44% of subjects treated with mifepristone. The hypokalemia responded to treatment with potassium supplementation and/or mineralocorticoid antagonist therapy (e.g., spironolactone or eplerenone).

MANAGEMENT: When mifepristone is used daily to control hyperglycemia secondary to hypercortisolism in patients with endogenous Cushing's syndrome, coadministration with other drugs that can prolong the QT interval should generally be avoided. Caution is recommended if no alternatives exist and concomitant use is required. Serum potassium should be assessed prior to starting mifepristone and 1 to 2 weeks following initiation of therapy or an increase in dosage, and periodically as needed. Hypokalemia must be corrected prior to initiation of mifepristone. Patients should be advised to seek medical attention if they experience potential signs and symptoms of hypokalemia such as fatigue, weakness, myalgia, muscle cramps, numbness, tingling, abdominal pain, constipation, palpitation, and irregular heart rhythm. Because mifepristone is eliminated slowly from the body, drug interactions may be observed for a prolonged period following discontinuation (approximately 2 to 3 weeks if mifepristone had been administered chronically to steady state).

References

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  2. Canadian Pharmacists Association "e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink" (2006):
  3. Cerner Multum, Inc. "Australian Product Information." O 0
  4. "Product Information. Korlym (mifepristone)." Corcept Therapeutics Incorporated (2012):
View all 4 references

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Drug and food interactions

Moderate

methadone food

Applies to: methadone

GENERALLY AVOID: Coadministration with grapefruit juice may increase the plasma concentrations of methadone. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. In 8 study subjects stabilized on methadone maintenance treatment, ingestion of regular strength grapefruit juice (200 mL one-half hour before and 200 mL simultaneously with the daily methadone dose) for five days resulted in an approximately 17% mean increase in methadone peak plasma concentration (Cmax) and systemic exposure (AUC) and a 14% mean decrease in apparent clearance for both the R(+) and S(-) enantiomers. Grapefruit juice did not affect the time to peak level (Tmax), terminal half-life, or apparent volume of distribution of methadone. No signs or symptoms of methadone toxicity or changes in intensity of withdrawal symptoms were reported in the study.

MANAGEMENT: Given the interindividual variability in the pharmacokinetics of methadone, a more significant interaction with grapefruit juice in certain patients cannot be ruled out. Patients treated with methadone should preferably avoid or limit the consumption of grapefruit juice, particularly during the induction of maintenance treatment.

References

  1. Iribarne C, Berthou F, Baird S, Dreano Y, Picart D, Bail JP, Beaune P, Menez JF "Involvement of cytochrome P450 3A4 enzyme in the N-demethylation of methadone in human liver microsomes." Chem Res Toxicol 9 (1996): 365-73
  2. Oda Y, Kharasch ED "Metabolism of methadone and levo-alpha-acetylmethadol (LAAM) by human intestinal cytochrome P450 3A4 (CYP3A4): potential contribution of intestinal metabolism to presystemic clearance and bioactivation." J Pharmacol Exp Ther 298 (2001): 1021-32
  3. Benmebarek M, Devaud C, Gex-Fabry M, et al. "Effects of grapefruit juice on the pharmacokinetics of the enantiomers of methadone." Clin Pharmacol Ther 76 (2004): 55-63
  4. Foster DJ, Somogyi AA, Bochner F "Methadone N-demethylation in human liver microsomes: lack of stereoselectivity and involvement of CYP3A4." Br J Clin Pharmacol 47 (1999): 403-12
View all 4 references

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Moderate

miFEPRIStone food

Applies to: mifepristone

ADJUST DOSING INTERVAL: Food may significantly increase the plasma concentrations of mifepristone.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of mifepristone. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Because pharmacokinetic interactions involving grapefruit juice are often subject to a high degree of interpatient variability, the extent to which a given patient may be affected is difficult to predict.

MANAGEMENT: When mifepristone is used daily to control hyperglycemia secondary to hypercortisolism in patients with endogenous Cushing's syndrome, it should be taken with food to achieve consistent plasma drug levels. Patients should be advised to avoid consuming grapefruit or grapefruit juice during treatment with mifepristone, as it may cause increased adverse effects such as headache, dizziness, fatigue, nausea, vomiting, cramping, diarrhea, hypokalemia, adrenal insufficiency, vaginal bleeding, arthralgia, peripheral edema, and hypertension. Because mifepristone is eliminated slowly from the body, the interaction with grapefruit juice may be observed for a prolonged period.

References

  1. "Product Information. Mifeprex (mifepristone)." Danco Laboratories PROD (2001):
  2. "Product Information. Korlym (mifepristone)." Corcept Therapeutics Incorporated (2012):

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Moderate

methadone food

Applies to: methadone

GENERALLY AVOID: Ethanol may potentiate the central nervous system (CNS) depressant effects of opioid analgesics. Concomitant use may result in additive CNS depression and impairment of judgment, thinking, and psychomotor skills. In more severe cases, hypotension, respiratory depression, profound sedation, coma, or even death may occur.

MANAGEMENT: Concomitant use of opioid analgesics with ethanol should be avoided.

References

  1. Linnoila M, Hakkinen S "Effects of diazepam and codeine, alone and in combination with alcohol, on simulated driving." Clin Pharmacol Ther 15 (1974): 368-73
  2. Sturner WQ, Garriott JC "Deaths involving propoxyphene: a study of 41 cases over a two-year period." JAMA 223 (1973): 1125-30
  3. Girre C, Hirschhorn M, Bertaux L, et al. "Enhancement of propoxyphene bioavailability by ethanol: relation to psychomotor and cognitive function in healthy volunteers." Eur J Clin Pharmacol 41 (1991): 147-52
  4. Levine B, Saady J, Fierro M, Valentour J "A hydromorphone and ethanol fatality." J Forensic Sci 29 (1984): 655-9
  5. Sellers EM, Hamilton CA, Kaplan HL, Degani NC, Foltz RL "Pharmacokinetic interaction of propoxyphene with ethanol." Br J Clin Pharmacol 19 (1985): 398-401
  6. Carson DJ "Fatal dextropropoxyphene poisoning in Northern Ireland. Review of 30 cases." Lancet 1 (1977): 894-7
  7. Rosser WW "The interaction of propoxyphene with other drugs." Can Med Assoc J 122 (1980): 149-50
  8. Edwards C, Gard PR, Handley SL, Hunter M, Whittington RM "Distalgesic and ethanol-impaired function." Lancet 2 (1982): 384
  9. Kiplinger GF, Sokol G, Rodda BE "Effect of combined alcohol and propoxyphene on human performance." Arch Int Pharmacodyn Ther 212 (1974): 175-80
View all 9 references

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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.

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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