Major sources of analytical interference for Carpine include cross-reactivity from the 10,11-epoxide metabolite and structurally similar drugs. Cross-reactivity of Carpine and its metabolite can vary in commercial immunoassays, from 0% for the Vitros assay to approximately 93.6% on the Dade Dimension. Other assays, such as MEIA (AxSYM), have moderate cross-reactivity (22%) . This cross-reactivity can be utilized to calculate the total amount of epoxide present, but chromatographic methods are preferred . Analytical interferences with Carpine immunoassays have been described for drugs that are structurally similar to Carpine, such as oxcarbazepine, which produce positive interference in Carpine analysis by EMIT . Cross-reactivity with Carpine analogs that are currently in development, such as eslicarbazepine, is not yet characterized. Because this new drug is a purified isomer, it is important to recognize that nonchiral chromatographic assays would not be able to distinguish between use of eslicarbazepine and use of racemic licarbazepine. NonCarpine analogs may also cross-react with Carpine assays. For example, Parant et al. reported that the antihistamine drug hydroxyzine and its metabolite, cetirizine, produced a false-positive result for Carpine using the particle-enhanced turbidimetric inhibition immunoassay (PETINIA) but not with EMIT or turbidimetry (ADVIA Centaur) .
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to Carpine.
What Other Drugs Interact with Carpine?
If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.
Carpine has severe interactions with at least 40 different drugs.
Carpine has serious interactions with at least 164 different drugs.
Carpine has moderate interactions with at least 277 different drugs.
Carpine has minor interactions with at least 76 different drugs.
This information does not contain all possible interactions or adverse effects. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns or for more information about this medicine.
Rare (0.01% to 0.1%): Disturbances of cardiac conduction
Very rare (less than 0.01%): Bradycardia, arrhythmias, AV-block with syncope, collapse, congestive heart failure, hypertension or hypotension, aggravation of coronary artery disease, thrombophlebitis, thromboembolism
Most of the cases of cardiovascular effects reported have occurred in patients receiving Carpine for trigeminal neuralgia. The reported effects included congestive heart failure, edema, hypotension, syncope and arrhythmias. In general, the doses were titrated quickly because of severe pain. Many of the doses were higher than those used to treat epilepsy. Many of the reported cardiovascular effects resolved after discontinuation of Carpine.
Agents That May Affect Tegretol Plasma Levels
When Carpine is given with drugs that can increase or decrease Carpine levels, close monitoring of Carpine levels is indicated and dosage adjustment may be required.
You should not take Carpine if you have a history of bone marrow suppression, if you are allergic to it, or take an antidepressant such as amitriptyline, desipramine, doxepin, imipramine, or nortriptyline.
TELL YOUR DOCTOR ABOUT ALL OTHER MEDICINES YOU USE. Some drugs can raise or lower your blood levels of Carpine, which may cause side effects or make this medicine less effective. Carpine can also affect blood levels of certain other drugs, making them less effective or increasing side effects.
Carpine may cause serious blood problems or a life-threatening skin rash or allergic reaction. Call your doctor if you have a fever, unusual weakness, bleeding, bruising, or a skin rash that causes blistering and peeling.
Some people have thoughts about suicide while taking seizure medicine. Stay alert to changes in your mood or symptoms. Report any new or worsening symptoms to your doctor.
Do not stop taking this medicine without asking your doctor first, even if you feel fine.
If you are pregnant, do not start or stop taking Carpine without your doctor's advice.
Outcome and Management
Carpine hepatotoxicity is usually rapidly reversible with stopping therapy, improvements beginning within 5 to 7 days. In cases of severe injury, progression to acute liver failure and death can occur, particularly in patients presenting with a hepatocellular pattern of serum enzyme elevations (Case 4). Corticosteroids have been used but with uncertain effectiveness for the hepatic components of the hypersensitivity syndrome. Rechallenge with Carpine is associated with rapid and more severe recurrence and should be avoided. Cross reactivity with other aromatic anticonvulsants (phenytoin, phenobarbital, primidone, oxcarbazepine and lamotrigine) is common, but not invariable. Patients with severe hypersensitivity to Carpine should avoid exposure to other aromatic anticonvulsants and be switched instead to agents such as a benzodiazepine, valproate, levetiracetam, gabapentin or pregabalin.