Carbamazepine with Viloxazine Interaction Details
Brand Names Associated with Carbamazepine
- Carbamazepine
- Carbatrol®
- Epitol®
- Equetro®
- Tegretol®
- Tegretol®-XR
- Teril®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 25, 2023
Interaction Effect
Carbamazepine toxicity (ataxia, nystagmus, diplopia, headache, vomiting, apnea, seizures, coma)
Interaction Summary
Viloxazine administered concurrently with carbamazepine increased carbamazepine steady-state serum levels significantly. These increased serum levels were associated with symptoms of carbamazepine toxicity (dizziness, ataxia, fatigue, drowsiness) in five of seven patients and four of seven patients in the aformentioned studies, respectively. The concentration of the active metabolite, carbamazepine-10,11-epoxide, was also increased . In another study by , viloxazine pharmacokinetics were not affected by the administration of carbamazepine.
Severity
Moderate
Onset
Delayed
Evidence
Probable
How To Manage Interaction
Downward adjustment of carbamazepine dosage may be necessary when adding viloxazine to drug therapy. Monitor serum carbamazepine concentrations closely.
Mechanism Of Interaction
Inhibition of carbamazepine hepatic metabolism by viloxazine
Literature Reports
A) The possibility of a drug interaction between viloxazine and carbamazepine was studied in seven epileptic patients stabilized on carbamazepine therapy. Viloxazine 100 mg three times daily was added to drug therapy for 21 days and significantly increased steady-state carbamazepine serum levels from an average of 8.1 mcg/mL before adding viloxazine to an average of 12.1 mcg/mL during the second and third weeks of viloxazine therapy (p less than 0.005). These increased levels were associated with mild symptoms of carbamazepine toxicity (dizziness, ataxia, fatigue, drowsiness) in five patients. Serum carbamazepine levels returned to normal and symptoms abated after discontinuing viloxazine .
B) Significant increases in serum carbamazepine and carbamazepine-10,11-epoxide levels during viloxazine therapy were investigated. The study was performed in six epileptic patients stabilized on carbamazepine. After three weeks of viloxazine administration, steady-state plasma carbamazepine levels increased by 55% (p less than 0.001), and carbamazepine-10,11-epoxide levels increased by 16% (p less than 0.001). Three of the six patients suffered from symptoms of carbamazepine intoxication. In a seventh patient, viloxazine had to be discontinued after two weeks due to severe carbamazepine intoxication .
C) The pharmacokinetics of viloxazine and whether chronic anticonvulsant therapy has any affect on viloxazine pharmacokinetics were studied in six epileptic patients taking one or two anticonvulsants (carbamazepine, phenobarbital, or phenytoin) and six drug-free control subjects. One oral viloxazine 200 mg dose followed by a single intravenous infusion of viloxazine 200 mg at least one week later were administered to each patient and control subject. Terminal half-lives were not affected by anticonvulsant therapy (4.3 +/- 1.5 hours for the patients and 4.3 +/- 1.8 hours for the control subjects). Absolute oral availability was 85% +/- 14%. Clearance and volume of distribution calculated from the intravenous dose to the patients were 124 +/- 11 mL/kg/hr and 0.73 +/-0.28 L/kg, respectively. The authors concluded that viloxazine pharmacokinetics did not appear to be significantly altered by carbamazepine, phenobarbital, or phenytoin .
Carbamazepine Overview
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Carbamazepine is used alone or in combination with other medications to control certain types of seizures in people with epilepsy. It is also used to treat trigeminal neuralgia (a condition that causes facial nerve pain). Carbamazepine extended-release capsules (Equetro brand only) are also used to treat episodes of mania (frenzied, abnormally excited or irritated mood) or mixed episodes (symptoms of mania and depression that happen at the same time) in patients with bipolar I disorder (manic-depressive disorder; a disease that causes episodes of depression, episodes of mania, and other abnormal moods). Carbamazepine is in a class of medications called anticonvulsants. It works by reducing abnormal electrical activity in the brain.
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Definitions
Severity Categories
Contraindicated
These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.
Major
This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.
Moderate
This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.
Minor
While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.
Onset
Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.
Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.
Evidence
Level of documentation of the interaction.
Established: The interaction is documented and substantiated in peer-reviewed medical literature.
Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.
How To Manage The Interaction
Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.
It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.
Mechanism Of Interaction
The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.
Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.
Where Does Our Information Come From?
Information for our drug interactions is compiled from several drug compendia, including:
The prescribing information for each drug, as published on DailyMED, is also used.
Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.
The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.