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Drug Interactions between delavirdine and rifampin

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

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Interactions between your drugs

Major

rifAMPin delavirdine

Applies to: rifampin and delavirdine

GENERALLY AVOID: Coadministration with potent inducers of CYP450 3A4 may significantly decrease the plasma concentrations of delavirdine, which is primarily metabolized by the isoenzyme. In seven HIV-infected subjects, administration of delavirdine (400 mg three times a day for 30 days) in combination with the potent CYP450 3A4 inducer rifampin (600 mg once daily on days 16 thru 30) decreased mean delavirdine peak plasma concentration (Cmax), systemic exposure (AUC) and trough plasma concentration (Cmin) by approximately 92%, 97% and 100%, respectively, compared to administration of delavirdine alone. Oral clearance of delavirdine also increased by nearly 27-fold in the presence of rifampin. When delavirdine (400 mg three times a day for 30 days) was given with rifabutin (300 mg once daily on days 16 thru 30) in seven HIV-positive subjects, mean delavirdine Cmax, AUC and Cmin decreased by about 75%, 84% and 95%, respectively, and oral clearance increased by approximately 5-fold. Likewise, population pharmacokinetic data from efficacy studies showed that delavirdine Cmin was reduced by approximately 90% in patients (n=8) treated with various dosages of phenytoin, phenobarbital, and/or carbamazepine who were given delavirdine 300 to 400 mg three times a day.

MANAGEMENT: Given the risk of reduced viral susceptibility and resistance development associated with subtherapeutic antiretroviral drug levels, concomitant use of delavirdine with potent CYP450 3A4 inducers should generally be avoided.

References (6)
  1. Borin MT, Chambers JH, Carel BJ, Gagnon S, Freimuth WW (1997) "Pharmacokinetic study of the interaction between rifampin and delavirdine mesylate." Clin Pharmacol Ther, 61, p. 544-53
  2. (2001) "Product Information. Rescriptor (delavirdine)." Pharmacia and Upjohn
  3. Borin MT, Chambers JH, Carel BJ, Freimuth WW, Aksentijevich S, Piergies AA (1997) "Pharmacokinetic study of the interaction between rifabutin and delavirdine mesylate in HIV-1 infected patients." Antiviral Res, 35, p. 53-63
  4. Burman WJ, Jones BE (2001) "Treatment of HIV-related tuberculosis in the era of effective antiretroviral therapy." Am J Respir Crit Care Med, 164, p. 7-12
  5. Tran JQ, Gerber JG, Kerr BM (2001) "Delavirdine: clinical pharmacokinetics and drug interactions." Clin Pharmacokinet, 40, p. 207-26
  6. (2000) "Notice to readers: updated guidelines for the use of rifabutin or rifampin for the treatment and prevention of tuberculosis among HIV-infected patients taking protease inhibitors or nonnucleoside reverse transcriptase inhibiotrs." MMWR Morb Mortal Wkly Rep, 49, p. 185-9

Drug and food interactions

Moderate

rifAMPin food

Applies to: rifampin

GENERALLY AVOID: Concurrent use of rifampin in patients who ingest alcohol daily may result in an increased incidence of hepatotoxicity. The increase in hepatotoxicity may be due to an additive risk as both alcohol and rifampin are individually associated with this adverse reaction. However, the exact mechanism has not been established.

ADJUST DOSING INTERVAL: Administration with food may reduce oral rifampin absorption, increasing the risk of therapeutic failure or resistance. In a randomized, four-period crossover phase I study of 14 healthy male and female volunteers, the pharmacokinetics of single dose rifampin 600 mg were evaluated under fasting conditions and with a high-fat meal. Researchers observed that administration of rifampin with a high-fat meal reduced rifampin peak plasma concentration (Cmax) by 36%, nearly doubled the time to reach peak plasma concentration (Tmax) but reduced overall exposure (AUC) by only 6%.

MANAGEMENT: The manufacturer of oral forms of rifampin recommends administration on an empty stomach, 30 minutes before or 2 hours after meals. Patients should be encouraged to avoid alcohol or strictly limit their intake. Patients who use alcohol and rifampin concurrently or have a history of alcohol use disorder may require additional monitoring of their liver function during treatment with rifampin.

References (6)
  1. (2022) "Product Information. Rifampin (rifAMPin)." Akorn Inc
  2. (2022) "Product Information. Rifampicin (rifampicin)." Mylan Pharmaceuticals Inc
  3. (2023) "Product Information. Rifadin (rifampicin)." Sanofi
  4. (2024) "Product Information. Rifadin (rifaMPICin)." Sanofi-Aventis Australia Pty Ltd
  5. Peloquin CA, Namdar R, Singleton MD, Nix DE (2024) Pharmacokinetics of rifampin under fasting conditions, with food, and with antacids https://pubmed.ncbi.nlm.nih.gov/9925057/
  6. (2019) "Product Information. Rofact (rifampin)." Bausch Health, Canada Inc.

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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