Clonazepam with Carbamazepine Interaction Details
Brand Names Associated with Clonazepam
- Clonazepam
- Klonopin®
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
Reduced plasma levels of clonazepam
Interaction Summary
Clonazepam and carbamazepine cotherapy has resulted in decreased clonazepam serum concentrations. This may be a result of carbamazepine enzyme induction. One study involving clonazepam administration to epileptic patients maintained on carbamazepine either alone or in combination with other anticonvulsants determined that clonazepam administration did not influence serum concentrations of carbamazepine .
Severity
Major
Onset
Delayed
Evidence
Probable
How To Manage Interaction
Clonazepam levels should be monitored whenever carbamazepine is added or withdrawn from therapy, or when the carbamazepine dose is changed. Also monitor the patient for seizure control.
Mechanism Of Interaction
Induction of CYP3A4-mediated clonazepam metabolism by carbamazepine
Literature Reports
A) The effect of carbamazepine on clonazepam plasma levels during chronic administration were evaluated in seven healthy volunteers . Subjects were given clonazepam 1 mg once daily for 29 consecutive days, and carbamazepine 200 mg was coadministered on days 8 to 29. Clonazepam plasma levels reached a steady-state level prior to the initiation of carbamazepine therapy. After the addition of carbamazepine, plasma clonazepam levels decreased over 5 to 15 days to a level 19% to 37% less than their prior steady-state concentrations. Carbamazepine also reduced clonazepam half-life. The proposed mechanism for this drug interaction is enzyme induction caused by carbamazepine.
B) The effects of clonazepam on serum levels of phenytoin, phenobarbital, and carbamazepine were studied in 22 epileptic patients who were receiving one or two of these drugs . Clonazepam 4 mg to 6 mg daily was added to their therapeutic regimens and anticonvulsant levels were determined weekly for at least six weeks. Of the nine patients receiving carbamazepine either as monotherapy or combined with another anticonvulsant, carbamazepine plasma concentrations averaged 8.1 mcg/mL prior to clonazepam and 8.3 mcg/mL after clonazepam therapy. The authors concluded that clonazepam has an insignificant effect on plasma concentrations of carbamazepine.
C) Concurrently administered clonazepam and carbamazepine were investigated in epileptic children . The steady-state plasma concentration of clonazepam was determined in 66 epileptic children who were receiving both carbamazepine and clonazepam. These levels were compared to the plasma levels of clonazepam in 188 other children who were receiving clonazepam as monotherapy. In another group of 12 children, some of whom were included in the previous groups, carbamazepine was added to their pre-existing regimen of clonazepam. Another group of 11 children was maintained on clonazepam and carbamazepine, and their therapeutic regimen was changed to clonazepam alone. All plasma levels were determined four or more weeks after maintaining the same dose and regimen. When comparing the plasma levels of clonazepam, children who received clonazepam monotherapy had a mean level of 30.9 ng/mL and children who were receiving therapy with clonazepam and carbamazepine had a mean level of 26.2 ng/mL. When carbamazepine was added to clonazepam monotherapy, steady-state plasma concentrations of clonazepam decreased from 47.5 ng/mL to 35.1 ng/mL. Conversely, when children who were receiving clonazepam and carbamazepine were switched to clonazepam monotherapy, plasma levels of clonazepam increased from 28.6 ng/mL to 34.4 ng/mL.
Clonazepam Overview
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Clonazepam is used alone or in combination with other medications to control certain types of seizures. It is also used to relieve panic attacks (sudden, unexpected attacks of extreme fear and worry about these attacks). Clonazepam is in a class of medications called benzodiazepines. It works by decreasing abnormal electrical activity in the brain.
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.