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Drug Interactions between Combogesic and ritonavir

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

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Interactions between your drugs

Minor

ibuprofen ritonavir

Applies to: Combogesic (acetaminophen / ibuprofen) and ritonavir

Ritonavir has a moderate affinity for the CYP450 2C9 microsomal enzyme and may variably affect drugs that are substrates of this enzyme. The area under the plasma concentration-time curves for these drugs may increase or decrease. If concomitant therapy is necessary, close monitoring for therapeutic and adverse effects is strongly recommended. Dosage adjustments should be made as necessary.

References

  1. (2001) "Product Information. Norvir (ritonavir)." Abbott Pharmaceutical

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Drug and food interactions

Major

acetaminophen food

Applies to: Combogesic (acetaminophen / ibuprofen)

GENERALLY AVOID: Chronic, excessive consumption of alcohol may increase the risk of acetaminophen-induced hepatotoxicity, which has included rare cases of fatal hepatitis and frank hepatic failure requiring liver transplantation. The proposed mechanism is induction of hepatic microsomal enzymes during chronic alcohol use, which may result in accelerated metabolism of acetaminophen and increased production of potentially hepatotoxic metabolites.

MANAGEMENT: In general, chronic alcoholics should avoid regular or excessive use of acetaminophen. Alternative analgesic/antipyretic therapy may be appropriate in patients who consume three or more alcoholic drinks per day. However, if acetaminophen is used, these patients should be cautioned not to exceed the recommended dosage (maximum 4 g/day in adults and children 12 years of age or older).

References

  1. Kaysen GA, Pond SM, Roper MH, Menke DJ, Marrama MA (1985) "Combined hepatic and renal injury in alcoholics during therapeutic use of acetaminophen." Arch Intern Med, 145, p. 2019-23
  2. O'Dell JR, Zetterman RK, Burnett DA (1986) "Centrilobular hepatic fibrosis following acetaminophen-induced hepatic necrosis in an alcoholic." JAMA, 255, p. 2636-7
  3. Seeff LB, Cuccherini BA, Zimmerman HJ, Adler E, Benjamin SB (1986) "Acetaminophen hepatotoxicity in alcoholics." Ann Intern Med, 104, p. 399-404
  4. Thummel KE, Slattery JT, Nelson SD (1988) "Mechanism by which ethanol diminishes the hepatotoxicity of acetaminophen." J Pharmacol Exp Ther, 245, p. 129-36
  5. McClain CJ, Kromhout JP, Peterson FJ, Holtzman JL (1980) "Potentiation of acetaminophen hepatotoxicity by alcohol." JAMA, 244, p. 251-3
  6. Kartsonis A, Reddy KR, Schiff ER (1986) "Alcohol, acetaminophen, and hepatic necrosis." Ann Intern Med, 105, p. 138-9
  7. Prescott LF, Critchley JA (1983) "Drug interactions affecting analgesic toxicity." Am J Med, 75, p. 113-6
  8. (2002) "Product Information. Tylenol (acetaminophen)." McNeil Pharmaceutical
  9. Whitcomb DC, Block GD (1994) "Association of acetaminopphen hepatotoxicity with fasting and ethanol use." JAMA, 272, p. 1845-50
  10. Bonkovsky HL (1995) "Acetaminophen hepatotoxicity, fasting, and ethanol." JAMA, 274, p. 301
  11. Nelson EB, Temple AR (1995) "Acetaminophen hepatotoxicity, fasting, and ethanol." JAMA, 274, p. 301
  12. Zimmerman HJ, Maddrey WC (1995) "Acetaminophen (paracetamol) hepatotoxicity with regular intake of alcohol: analysis of instances of therapeutic misadventure." Hepatology, 22, p. 767-73
View all 12 references

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Moderate

ritonavir food

Applies to: ritonavir

ADJUST DOSING INTERVAL: Administration with food may modestly affect the bioavailability of ritonavir from the various available formulations. When the oral solution was given under nonfasting conditions, peak ritonavir concentrations decreased 23% and the extent of absorption decreased 7% relative to fasting conditions. Dilution of the oral solution (within one hour of dosing) with 240 mL of chocolate milk or a nutritional supplement (Advera or Ensure) did not significantly affect the extent and rate of ritonavir absorption. When a single 100 mg dose of the tablet was administered with a high-fat meal (907 kcal; 52% fat, 15% protein, 33% carbohydrates), approximately 20% decreases in mean peak concentration (Cmax) and systemic exposure (AUC) were observed relative to administration after fasting. Similar decreases in Cmax and AUC were reported when the tablet was administered with a moderate-fat meal. In contrast, the extent of absorption of ritonavir from the soft gelatin capsule formulation was 13% higher when administered with a meal (615 KCal; 14.5% fat, 9% protein, and 76% carbohydrate) relative to fasting.

MANAGEMENT: Ritonavir should be taken with meals to enhance gastrointestinal tolerability.

References

  1. (2001) "Product Information. Norvir (ritonavir)." Abbott Pharmaceutical

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Moderate

ibuprofen food

Applies to: Combogesic (acetaminophen / ibuprofen)

GENERALLY AVOID: The concurrent use of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) and ethanol may lead to gastrointestinal (GI) blood loss. The mechanism may be due to a combined local effect as well as inhibition of prostaglandins leading to decreased integrity of the GI lining.

MANAGEMENT: Patients should be counseled on this potential interaction and advised to refrain from alcohol consumption while taking aspirin or NSAIDs.

References

  1. (2002) "Product Information. Motrin (ibuprofen)." Pharmacia and Upjohn

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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

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