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Drug Interactions between Klonopin and ritonavir

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

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Interactions between your drugs

Moderate

clonazePAM ritonavir

Applies to: Klonopin (clonazepam) and ritonavir

MONITOR: The coadministration of ritonavir and benzodiazepines that are substrates of the CYP450 3A4 enzymatic pathway may result in elevated plasma concentrations of the latter. The mechanism is decreased clearance of benzodiazepines due to inhibition of CYP450 3A4 activity by ritonavir.

MANAGEMENT: While clinical data are not available for all agents in the class, the possibility of prolonged and/or increased pharmacologic effects of benzodiazepines, including sedation and respiratory depression, should be considered in patients receiving ritonavir therapy. It may be appropriate to use lower benzodiazepine dosages in these patients, or use agents that are not metabolized by the CYP450 3A4 pathway (e.g., lorazepam, oxazepam, temazepam).

References

  1. (2001) "Product Information. Norvir (ritonavir)." Abbott Pharmaceutical
  2. Michalets EL (1998) "Update: clinically significant cytochrome P-450 drug interactions." Pharmacotherapy, 18, p. 84-112
  3. Greenblatt DJ, vonMoltke LL, Harmatz JS, Durol ALB, Daily JP, Graf JA, Mertzanis P, Hoffman JL, Shader RI (2000) "Alprazolam-ritonavir interaction: Implications for product labeling." Clin Pharmacol Ther, 67, p. 335-41

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Drug and food interactions

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

clonazePAM food

Applies to: Klonopin (clonazepam)

GENERALLY AVOID: Acute ethanol ingestion may potentiate the CNS effects of many benzodiazepines. Tolerance may develop with chronic ethanol use. The mechanism may be decreased clearance of the benzodiazepines because of CYP450 hepatic enzyme inhibition. Also, it has been suggested that the cognitive deficits induced by benzodiazepines may be increased in patients who chronically consume large amounts of alcohol.

MANAGEMENT: Patients should be advised to avoid alcohol during benzodiazepine therapy.

References

  1. MacLeod SM, Giles HG, Patzalek G, Thiessen JJ, Sellers EM (1977) "Diazepam actions and plasma concentrations following ethanol ingestion." Eur J Clin Pharmacol, 11, p. 345-9
  2. Whiting B, Lawrence JR, Skellern GG, Meier J (1979) "Effect of acute alcohol intoxication on the metabolism and plasma kinetics of chlordiazepoxide." Br J Clin Pharmacol, 7, p. 95-100
  3. Divoll M, Greenblatt DJ, Lacasse Y, Shader RI (1981) "Benzodiazepine overdosage: plasma concentrations and clinical outcome." Psychopharmacology (Berl), 73, p. 381-3
  4. Juhl RP, Van Thiel DH, Dittert LW, Smith RB (1984) "Alprazolam pharmacokinetics in alcoholic liver disease." J Clin Pharmacol, 24, p. 113-9
  5. Ochs HR, Greenblatt DJ, Arendt RM, Hubbel W, Shader RI (1984) "Pharmacokinetic noninteraction of triazolam and ethanol." J Clin Psychopharmacol, 4, p. 106-7
  6. Staak M, Raff G, Nusser W (1979) "Pharmacopsychological investigations concerning the combined effects of dipotassium clorazepate and ethanol." Int J Clin Pharmacol Biopharm, 17, p. 205-12
  7. Nichols JM, Martin F, Kirkby KC (1993) "A comparison of the effect of lorazepam on memory in heavy and low social drinkers." Psychopharmacology (Berl), 112, p. 475-82
View all 7 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.

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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