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Drug Interactions between lacosamide and ritonavir

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

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Interactions between your drugs

Moderate

ritonavir lacosamide

Applies to: ritonavir and lacosamide

MONITOR: Coadministration of strong inhibitors of CYP450 3A4 and/or CYP450 2C9 in patients with renal or hepatic impairment may significantly increase lacosamide plasma concentrations and increase the risk of lacosamide toxicity. The presumed mechanism is additive reduction in lacosamide clearance. Pharmacokinetic studies have shown lacosamide systemic exposure (AUC) may increase by 25% to 60% in patients with renal and/or hepatic impairment. Additional increases in lacosamide plasma concentrations are possible due to inhibition of the CYP450 3A4 and 2C9-mediated formation of O-desmethyl metabolite (inactive). Approximately 30% of a lacosamide dose is excreted as O-desmethyl metabolite in the urine. This interaction has not been established in vivo but is possible based on in vitro data.

MANAGEMENT: For patients with renal and/or hepatic impairment concomitantly receiving a strong CYP450 3A4 and/or CYP450 2C9 inhibitor, lacosamide dose reductions in addition to those recommended for renal and/or hepatic impairment may be necessary. Manufacturer labeling should be consulted for dose recommendations in renal and/or hepatic impairment. Patients should be advised to notify their physician if they experience dizziness, lightheadedness, fainting, or irregular heartbeat. Lacosamide dose adjustments may be necessary whenever a strong CYP450 3A4 and/or 2C9 inhibitor is added to or withdrawn from therapy in patients with renal and/or hepatic impairment.

References

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. Cerner Multum, Inc. "Australian Product Information."
  3. (2008) "Product Information. Vimpat (lacosamide)." UCB Pharma Inc

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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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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

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.