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Drug Interactions between atazanavir and Dolophine

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

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Interactions between your drugs

Minor

methadone atazanavir

Applies to: Dolophine (methadone) and atazanavir

Atazanavir does not appear to significantly affect the pharmacokinetics of methadone. In 16 HIV-negative patients on chronic methadone therapy for treatment of opiate dependency, coadministration of atazanavir (400 mg orally once daily for 14 days) reduced the steady-state peak plasma concentration (Cmax) of the pharmacologically active R(+) enantiomer of methadone by just 9% compared to administration of methadone alone. The AUC of R(+) methadone increased by 3% and the plasma trough concentration (Cmin) increased by 11% during atazanavir cotreatment. These differences were not statistically significant, and clinically relevant symptoms of opiate withdrawal or excess were not detected. For S(-) methadone, which is pharmacologically inactive, the Cmax, AUC and Cmin decreased by 21%, 15% and 10%, respectively, with atazanavir. For total (racemic) methadone, the Cmax and AUC decreased by 15% and 6%, respectively, and Cmin increased by 2% with atazanavir. Methadone also seems to have negligible effects on atazanavir pharmacokinetics, as atazanavir exposures in the study were within the range of values previously reported for healthy and HIV-infected subjects. Based on these findings, no dosage adjustments are necessary for either methadone or atazanavir during coadministration.

References

  1. Friedland G, Andrews L, Schreibman T, et al. (2005) "Lack of an effect of atazanavir on steady-state pharmacokinetics of methadone in patients chronically treated for opiate addiction." AIDS, 19, p. 1635-1641

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Drug and food interactions

Moderate

methadone food

Applies to: Dolophine (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 (1996) "Involvement of cytochrome P450 3A4 enzyme in the N-demethylation of methadone in human liver microsomes." Chem Res Toxicol, 9, p. 365-73
  2. Oda Y, Kharasch ED (2001) "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, p. 1021-32
  3. Benmebarek M, Devaud C, Gex-Fabry M, et al. (2004) "Effects of grapefruit juice on the pharmacokinetics of the enantiomers of methadone." Clin Pharmacol Ther, 76, p. 55-63
  4. Foster DJ, Somogyi AA, Bochner F (1999) "Methadone N-demethylation in human liver microsomes: lack of stereoselectivity and involvement of CYP3A4." Br J Clin Pharmacol, 47, p. 403-12
View all 4 references

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Moderate

atazanavir food

Applies to: atazanavir

ADJUST DOSING INTERVAL: Administration of atazanavir with food enhances oral bioavailability and reduces pharmacokinetic variability. According to the manufacturer, administration with a light meal increased the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of a single 400 mg dose of atazanavir by 57% and 70%, respectively, relative to the fasting state. Administration with a high-fat meal resulted in a mean increase of 35% in atazanavir AUC and no change in Cmax compared to fasting. The coefficient of variation of AUC and Cmax decreased by approximately one-half when given with either a light or high-fat meal compared to the fasting state.

MANAGEMENT: To ensure maximal oral absorption, atazanavir should be administered with or immediately after a meal.

References

  1. (2003) "Product Information. Reyataz (atazanavir)." Bristol-Myers Squibb

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Moderate

methadone food

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


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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.