Carbamazepine is not recommended for use simultaneously with monoamine oxidase (MAO) inhibitors. Before using the drug, MAO inhibitors should be withdrawn at least 2 weeks or, if the clinical situation permits, even for a longer period.
Cytochrome P4503A4 (CYP3A4) is the main isoenzyme providing the formation of carbamazepine-10,11-epoxide (active metabolite). Simultaneous use of an inhibitor of the isoenzyme CYP3A4 with the preparation can lead to an increase in the concentration of carbamazepine in the plasma, which, in turn, can cause side reactions. Simultaneous use of inducers of the CYP3A4 isoenzyme may lead to an acceleration of the metabolism of carbamazepine and, thus, to a possible decrease in its concentration in the plasma and, consequently, to a possible decrease in the severity of the therapeutic effect of the drug. The cancellation of simultaneously taken inducers of the isoenzyme CYP3A4 can reduce the rate of biotransformation of carbamazepine, and, as a result, lead to an increase in the concentration of carbamazepine in the blood plasma.
Carbamazepine is a potent inducer of the isoenzyme CYP3A4 and other enzyme hepatic systems of the first and second phases of drug metabolism and, when used simultaneously with drugs metabolized by the CYP3A4 isoenzyme, can induce metabolism induction and a decrease in their concentration in the plasma.
Since the conversion of carbamazepine-10,11-epoxide to carbamazepine-10,11-trans-diol occurs with the aid of microsomal epoxide hydrolase, the use of carbamazepine simultaneously with the inhibitors of microsomal epoxide hydrolase can lead to an increase in the plasma concentration of carbamazepine-10,11-epoxide.
Drugs that can increase the concentration of carbamazepine in blood plasma:
- analgesic and non-steroidal anti-inflammatory drugs: dextropropoxyphene, ibuprofen;
- antineoplastic agents (androgen): danazol;
-antibiotics: macrolide (for example, erythromycin, troleandomycin, josamycin, clarithromycin), ciprofloxacin;
- antidepressants: possibly, desipramine, fluoxetine, fluvoxamine, nefazodone, paroxetine, trazodone, viloxazine;
- antiepileptic drugs: styipentol, vigabatrin;
- antifungal agents: azole derivatives (for example, itraconazole, ketoconazole, fluconazole, voriconazole). Alternative anticonvulsants may be recommended to patients receiving voriconazole or itraconazole;
- blockers of histamine H2 receptors: loratadine, terfenadine;
- antipsychotic drugs (antipsychotics): olanzapine;
- anti-tuberculosis drugs: isoniazid;
- antiviral agents: HIV protease inhibitors (eg, ritonavir);
- antiglaucoma agents (inhibitors of carbonic anhydrase): acetazolamide;
- antihypertensive drugs (blockers of "slow" calcium channels): verapamil, diltiazem;
- antiulcer drugs (proton pump inhibitors, histamine H2 receptor blockers): omeprazole, perhaps, cimetidine;
- muscle relaxants: oxybutynin, dantrolene;
- antiplatelet agents: ticlopidine;
- other medicines and food products: grapefruit juice, nicotinamide (only in high doses).
Since an increase in the concentration of carbamazepine in the blood plasma can lead to the occurrence of adverse reactions (eg, dizziness, drowsiness, ataxia, diplopia),in these situations, the dose of the drug should be corrected and / or the concentration of carbamazepine in the blood plasma regularly determined.
Drugs that can increase the concentration of carbamazepine-10,11-epoxide in blood plasma: loxapine, quetiapine, primidon, progabide, valproic acid, valnoktamide and valpromid.
Since an increase in the concentration of carbamazepine-10,11-epoxide in blood plasma can lead to side reactions (for example, dizziness, drowsiness, ataxia, diplopia), in these situations, the dosage of the drug should be corrected and / or the carbamazepine concentration 10,11 -epoxide in the blood plasma.
Drugs that can reduce the concentration of carbamazepine in blood plasma:
- antiepileptics: felbamate, mezuximide, oxcarbazepine, phenobarbital, fensuximide, phenytoin (in order to avoid intoxication with phenytoin and the appearance of subtherapeutic concentrations of carbamazepine, the recommended plasma concentration of phenytoin should be no more than 13 μg / ml before addition to carbamazepine) and phosphenytoin, primidon, and although the data is partially contradictory, it is also possible that clonazepam;
- antineoplastic agents: cisplatin or doxorubicin;
- anti-tuberculosis drugs: rifampicin;
- bronchodilating agents: theophylline, aminophylline;
- remedy for acne (retinoids): isotretinoin;
- other medicines and food products: herbal preparations containing St. John's wort.
With simultaneous use with the above drugs, you may need to adjust the dose of carbamazepine.
The effect of carbamazepine on the plasma concentration of drugs used as concomitant therapy
With simultaneous use with carbamazepine, a decrease in plasma concentration, a decrease or even a complete cessation of action of certain drugs is possible.
With simultaneous use with carbamazepine, you may need to adjust the doses of the following drugs:
- analgesic and non-steroidal anti-inflammatory drugs: buprenorphine, methadone, paracetamol (long-term use of carbamazepine and paracetamol (acetaminophen) may lead to the development of hepatotoxic effects), phenazone, tramadol;
- antibiotics: doxycycline, rifabutin;
- indirect anticoagulants: warfarin, fenprokumone, dicoumarol and acenocoumarol;
- antidepressants: bupropion, citalopram, mianserin, nefazodone, sertraline, trazodone, tricyclic antidepressants (imipramine, amitriptyline, nortriptyline, clomipramine);
- antiemetics: aprepitant;
- antiepileptic drugs: clobazam, clonazepam, ethosuximide, felbamate, lamotrigine, oxcarbazepine, primidon, tiagabine, topiramate, valproic acid, zonisamide. To avoid intoxication with phenytoin and the occurrence of subtherapeutic concentrations of carbamazepine, the recommended plasma concentration of phenytoin should be no more than 13 μg / ml before addition to carbamazepine. There are reports that, when taking carbamazepine, the concentration of mephenytoin in the blood plasma may increase (in rare cases);
- antifungal agents: itraconazole, voriconazole.
Alternative anticonvulsants may be recommended to patients receiving voriconazole or itraconazole;
- anthelmintic agents: praziquantel, albendazole;
- antineoplastic agents: imatinib, cyclophosphamide, lapatinib, tessirolimus;
- antipsychotic drugs (antipsychotics): clozapine, haloperidol, bromperidol, olanzapine, quetiapine, risperidone, ziprasidone, aripiprazole, paliperidone;
- antiviral agents: HIV protease inhibitors (indinavir, ritonavirsaquinavir);
- anxiolytic means: alprazolam, midazolam;
- bronchodilating agents: theophylline;
- Contraceptive means: hormonal contraceptives (alternative methods of contraception are necessary);
- drugs for the treatment of cardiovascular diseases systems: blockers "slow" calcium channels of the dihydropyridine group (felodipine), simvastatin, atorvastatin, lovastatin, cerivastatin, ivabradine;
- cardiac glycosides: digoxin;
- glucocorticosteroids: prednisolone, dexamethasone;
- funds for the treatment of erectile dysfunction: tadalafil;
- immunosuppressive agents: ciclosporin, everolimus, tacrolimus, sirolimus;
- funds for the treatment of thyroid diseases: levothyroxine;
- Other medicines and food products: preparations containing estrogens and / or progesterone.
Combinations that should be taken into account
With the simultaneous use of carbamazepine with levetiracetam in some cases, increased toxic effects of carbamazepine. There are reports of increased hepatotoxicity caused by isoniazid, when it was used concomitantly with carbamazepine. The combined use of carbamazepine and lithium or metoclopramide, as well as carbamazepine and neuroleptics (haloperidol, thioridazine) may lead to an increase in the incidence of unwanted neurologic reactions (in the case of the latter combination, even with therapeutic concentrations of active substances in the blood plasma).
The simultaneous use of carbamazepine with certain diuretic drugs (hydrochlorothiazide, furosemide) can lead to hyponatremia, accompanied by clinical manifestations.
Carbamazepine may exhibit antagonism to the action of nondepolarizing muscle relaxants (for example, pancuronium bromide). If such a combination of drugs is used, it may be necessary to increase the dose of these muscle relaxants; careful monitoring of patients should be carried out, as possible a faster, than expected, cessation of muscle relaxants.
Reported the occurrence of bleeding in women between menstruation in cases when hormonal contraceptives were used simultaneously. The drug may reduce the effect of hormonal contraceptives due to the induction of microsomal enzymes.
Carbamazepine, as well as other psychotropic drugs, can reduce the tolerance of alcohol. In this regard, the patient is recommended to abandon the use of alcohol.
Interaction with serological reactions
Carbamazepine can lead to a false positive result of determining the concentration of perphenazine by high-performance liquid chromatography.
Carbamazepine and 10,11-carbamazepine epoxide can lead to false-positive results in the determination of the concentration of tricyclic antidepressants by the method of polarization fluorescent immunoassay.