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Drug Interactions between Cometriq and vemurafenib

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

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Interactions between your drugs

Major

vemurafenib cabozantinib

Applies to: vemurafenib and Cometriq (cabozantinib)

GENERALLY AVOID: Vemurafenib can cause concentration-dependent prolongation of the QT interval. Theoretically, coadministration with other agents that can prolong the QT interval may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. The effect of vemurafenib 960 mg administered twice daily on QTc interval was evaluated in a multicenter, open-label, single-arm study consisting of 132 patients with BRAF V600E mutation-positive metastatic melanoma. No changes in mean QTc interval exceeding 20 ms from baseline were detected in the trial. In the first month of treatment, the largest mean increase from baseline was 12.8 ms, observed at 2 hours post-dose on Day 15. In the first 6 months of treatment, the largest mean increase from baseline was 15.1 ms, which was detected at a predose time point. In general, the risk of an individual agent or a combination of agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia, hypocalcemia). Moreover, the extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s).

MANAGEMENT: Coadministration of vemurafenib with other drugs that can prolong the QT interval is not recommended. ECG and serum electrolytes, including potassium, magnesium and calcium, should be monitored before starting vemurafenib therapy and after dose modification. An ECG should also be obtained 15 days after treatment initiation, monthly during the first 3 months of treatment, and every 3 months thereafter (or more often as clinically indicated). Vemurafenib should not be started in the presence of uncorrected electrolyte abnormalities or a baseline QTc greater than 500 ms. Likewise, treatment should be interrupted if QTc exceeds 500 ms. Any electrolyte abnormalities must then be corrected and cardiac risk factors for QT prolongation (e.g., congestive heart failure, bradyarrhythmias) under control prior to resuming treatment. Vemurafenib may be restarted once QTc decreases below 500 ms, but at a reduced dosage as described in the product labeling. Permanent discontinuation of treatment is recommended if, after correction of associated risk factors, both the QTc is greater than 500 ms and the QTc increase is greater than 60 ms from pretreatment values. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope.

References

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. Canadian Pharmacists Association (2006) e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink
  3. Cerner Multum, Inc. "Australian Product Information."
  4. (2011) "Product Information. Zelboraf (vemurafenib)." Genentech
View all 4 references

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Drug and food interactions

Moderate

cabozantinib food

Applies to: Cometriq (cabozantinib)

ADJUST DOSING INTERVAL: Food may alter the oral bioavailability of cabozantinib. When healthy subjects were given a single 140 mg oral dose with a high-fat meal, cabozantinib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 41% and 57%, respectively, relative to administration under fasting conditions. In clinical studies, patients were administered cabozantinib without food.

GENERALLY AVOID: Coadministration with grapefruit juice is likely to increase the plasma concentrations of cabozantinib, which is primarily metabolized by CYP450 3A4. However, the interaction has not been studied. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit.

MANAGEMENT: Cabozantinib should be administered at least one hour before or two hours after a meal. The consumption of grapefruit, grapefruit juice, and supplements that contain grapefruit extract should be avoided.

References

  1. (2012) "Product Information. Cometriq (cabozantinib)." Exelixis Inc

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Therapeutic duplication warnings

Therapeutic duplication is the use of more than one medicine from the same drug category or therapeutic class to treat the same condition. This can be intentional in cases where drugs with similar actions are used together for demonstrated therapeutic benefit. It can also be unintentional in cases where a patient has been treated by more than one doctor, or had prescriptions filled at more than one pharmacy, and can have potentially adverse consequences.

Duplication

Multikinase inhibitors

Therapeutic duplication

The recommended maximum number of medicines in the 'multikinase inhibitors' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'multikinase inhibitors' category:

  • Cometriq (cabozantinib)
  • vemurafenib

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.


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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.