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Drug Interactions between clarithromycin and Vanspar

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

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Interactions between your drugs

Moderate

clarithromycin busPIRone

Applies to: clarithromycin and Vanspar (buspirone)

MONITOR: The combination of buspirone and some macrolide antibiotics may lead to elevated buspirone concentrations and adverse effects. The mechanism may be due to macrolide inhibition of CYP450 3A4 metabolism of buspirone. In one study, concomitant administration of buspirone with erythromycin resulted in a 5-fold and 6-fold increase in Cmax and AUC, respectively, of buspirone concentrations.

MANAGEMENT: Patients should be monitored for adverse buspirone effects, such as increased sedation. A reduction in dosage of buspirone may be necessary. Some authorities suggest a buspirone dose of 2.5 mg twice daily with subsequent dose adjustments based on clinical response.

References

  1. (2002) "Product Information. Buspar (buspirone)." Bristol-Myers Squibb
  2. Kivisto KT, Lamberg TS, Kantola T, Neuvonen PJ (1997) "Plasma buspirone concentrations are greatly increased by erythromycin and itraconazole." Clin Pharmacol Ther, 62, p. 348-54
  3. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  4. Cerner Multum, Inc. "Australian Product Information."
View all 4 references

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Drug and food interactions

Moderate

busPIRone food

Applies to: Vanspar (buspirone)

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

ADJUST DOSING INTERVAL: In a small, randomized, crossover study, the consumption of large amounts of grapefruit juice (compared to water) was associated with significantly increased plasma buspirone concentrations, slightly prolonged elimination half-lives, and delayed times to reach peak drug concentration. The perceived pharmacodynamic effect of buspirone, as measured by subjective drowsiness and overall subjective drug effect, was also enhanced by grapefruit juice. These alterations may stem from the 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: Patients receiving buspirone should be advised to avoid consumption of alcohol. Patients also should preferably avoid the consumption of large amounts of grapefruits and grapefruit juice to prevent any undue fluctuations in plasma drug levels. If this is not possible, the buspirone dose should be taken at least 2 hours before or 8 hours after grapefruit or grapefruit juice. Monitoring for increased CNS depression is recommended.

References

  1. (2002) "Product Information. Buspar (buspirone)." Bristol-Myers Squibb
  2. Lilja JJ, Kivisto KT, Backman JT, Lamberg TS, Neuvonen PJ (1998) "Grapefruit juice substantially increases plasma concentrations of buspirone." Clin Pharmacol Ther, 64, p. 655-60
  3. 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

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Minor

clarithromycin food

Applies to: clarithromycin

Grapefruit juice may delay the gastrointestinal absorption of clarithromycin but does not appear to affect the overall extent of absorption or inhibit the metabolism of clarithromycin. The mechanism of interaction is unknown but may be related to competition for intestinal CYP450 3A4 and/or absorptive sites. In an open-label, randomized, crossover study consisting of 12 healthy subjects, coadministration with grapefruit juice increased the time to reach peak plasma concentration (Tmax) of both clarithromycin and 14-hydroxyclarithromycin (the active metabolite) by 80% and 104%, respectively, compared to water. Other pharmacokinetic parameters were not significantly altered. This interaction is unlikely to be of clinical significance.

References

  1. Cheng KL, Nafziger AN, Peloquin CA, Amsden GW (1998) "Effect of grapefruit juice on clarithromycin pharmacokinetics." Antimicrob Agents Chemother, 42, p. 927-9

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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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