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Drug Interactions between buspirone and nafcillin

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

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Interactions between your drugs

Moderate

nafcillin busPIRone

Applies to: nafcillin and buspirone

MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations and pharmacologic effects of buspirone, which is primarily metabolized by the isoenzyme. Conversely, discontinuation of an inducer may increase buspirone plasma concentrations and increase the risk of central nervous system depression and other adverse effects. When a single 30 mg dose of buspirone was administered following treatment with the potent CYP450 3A4 inducer rifampin (600 mg once daily for 5 days) in 10 healthy volunteers, mean buspirone peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by approximately 84% and 90%, respectively, compared to administration following placebo. None of the subjects had a measurable plasma buspirone concentration at 6, 8 or 10 hours after given rifampin, while buspirone concentration could be determined up to 10 hours in all subjects after placebo. Pharmacodynamic effects of buspirone were also significantly reduced by rifampin in the study. Similar results were reported in another pharmacokinetic study conducted by the same group of investigators.

MANAGEMENT: The potential for diminished pharmacologic effects of buspirone should be considered during coadministration with CYP450 3A4 inducers. Pharmacologic response to buspirone should be monitored more closely whenever a CYP450 3A4 inducer is added to or withdrawn from therapy, and the buspirone dosage adjusted as necessary.

References

  1. (2002) "Product Information. Buspar (buspirone)." Bristol-Myers Squibb
  2. Lamberg TS, Kivisto KT, Neuvonen PJ (1998) "Concentrations and effects of buspirone are considerably reduced by rifampicin." Br J Clin Pharmacol, 45, p. 381-5
  3. Kivisto KT, Lamberg TS, Neuvonen PJ (1999) "Interactions of buspirone with itraconazole and rifampicin: Effects on the pharmacokinetics of the active 1-(2-pyrimidinyl)-piperazine metabolite of buspirone." Pharmacol Toxicol, 84, p. 94-7

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Drug and food interactions

Moderate

nafcillin food

Applies to: nafcillin

ADJUST DOSING INTERVAL: Certain penicillins may exhibit reduced gastrointestinal absorption in the presence of food. The therapeutic effect of the antimicrobial may be reduced.

MANAGEMENT: The interacting penicillin should be administered one hour before or two hours after meals. Penicillin V and amoxicillin are not affected by food and may be given without regard to meals.

References

  1. Neu HC (1974) "Antimicrobial activity and human pharmacology of amoxicillin." J Infect Dis, 129, s123-31
  2. Welling PG, Huang H, Koch PA, Madsen PO (1977) "Bioavailability of ampicillin and amoxicillin in fasted and nonfasted subjects." J Pharm Sci, 66, p. 549-52
  3. McCarthy CG, Finland M (1960) "Absorption and excretion of four penicillins." N Engl J Med, 263, p. 315-26
  4. Cronk GA, Wheatley WB, Fellers GF, Albright H (1960) "The relationship of food intake to the absorption of potassium alpha-phenoxyethyl penicillin and potassium phenoxymethyl penicillin from the gastrointestinal tract." Am J Med Sci, 240, p. 219-25
  5. Klein JO, Sabath LD, Finland M (1963) "Laboratory studies on oxacillin. I: in vitro activity against staphylococci and some other bacterial pathogens. II: absorption and urinary excretion in normal young." Am J Med Sci, 245, p. 399-411
  6. Neuvonen PJ, Elonen E, Pentikainen PJ (1977) "Comparative effect of food on absorption of ampicillin and pivampicillin." J Int Med Res, 5, p. 71-6
View all 6 references

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Moderate

busPIRone food

Applies to: 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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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

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