Pharmacodynamic interaction Preparations, They can cause a bidirectional ventricular tachycardia of the type "pirouette"
Co-administration of such drugs is contraindicated, as the risk of potentially lethal ventricular tachycardia increases by the type of "pirouette". Such drugs include:
- Antiarrhythmics: IА class (quinidine, hydroquinidine, disopyramide, procainamide), sotalol, beprideal.
- Other (non-antiarrhythmic) drugs, such as: wincamine; some neuroleptics: phenothiazines (chlorpromazine, tsiammazin, levopromazin, thioridazine, trifluoperazine, fluphenazine), benzamides (amisulfpride, sultopride, sulpride, tiapride, velapride), butyrophenones (droperidol, canterRidol), sertindole, pimozide; tricyclic antidepressants; cisapride; macrolide antibiotics (erythromycin with intravenous administration, spiramycin); azoles; antimalarial drugs (quinine, chloroquine, mefloquine, halofantrine, lumefantrine); pentamidine with parenteral administration; diphenamyl methyl sulfate; misolastine; astemizole; terfenadine.
Drugs that increase the duration of the QT interval
The combined use of amiodarone with these drugs should be based on a careful assessment of the relationship between expected benefit and potential risk (increased risk of developing pirouette-type ventricular tachycardia), using these combinations, it is necessary to constantly monitor the patient's ECG (for elongation of the QT interval), potassium and magnesium in the blood. In patients receiving amiodarone, fluoroquinolones should be avoided, including moxifloxacin.
Drugs that reduce heart rate or cause automatic or conduction disorders
Simultaneous reception of these drugs with amiodarone is not recommended. Beta-adrenoblockers, blockers of "slow" calcium channels, decreasing heart rate (verapamil, diltiazem), can lead to the development of excessive bradycardia and cause conduction disorders.
Preparations, capable of causing hypokalemia, which increases the risk of developing ventricular tachycardia by the type of "pirouette"
Combination of amiodarone with:
- laxatives, stimulating intestinal peristalsis (if necessary, laxatives of other groups should be prescribed). Caution is required when using amiodarone in conjunction with:
- diuretics, causing hypokalemia (in monotherapy or in combination with other drugs);
- systemic corticosteroids (glucocorticosteroids, mineralocorticosteroids) and tetracosactide;
- amphotericin B (intravenous administration).
During treatment with amiodarone it is necessary to regularly monitor the electrolyte content in the blood and the duration of the QT interval. In the case of ventricular tachycardia of the type "pirouette" should not be usedantiarrhythmic drugs (ventricular pacing should be started, and intravenous magnesium salts may be injected).
Preparations for inhalation anesthesia:
The possibility of developing the following serious complications in patients taking amiodarone on the background of general anesthesia: bradycardia (resistant to atropine administration), arterial hypotension, intracardiac conduction disturbance, reduction of cardiac output. There were very rare cases of severe complications from the respiratory system (acute respiratory distress syndrome of adults - sometimes fatal, which developed immediately after surgery, the occurrence is associated with high concentrations of oxygen).
Preparations, truncating heart rate:
Clonidine, guanfacine; cholinesterase inhibitors (donepezil, galantamine, rivastigmine, tacrine, ambenonium chloride, pyridostigmine bromide, neostigmine bromide); m-cholinomimetics (pilocarpine); beta-blockers - increase the risk of developing excessive bradycardia.
Influence of amiodarone on other drugs
Amiodarone and / or its metabolite, desethylamiodarone, inhibit the isoenzymes CYP1A1, CYP1A2, CYP3A4, CYP2C9, CYP2D6, which can increase the system exposure time of preparations that are their substrates. Due to the high duration of amiodarone excretion, this interaction can be observed even a few months after discontinuation of its administration.
Medications, which are substrates of the isoenzyme CYP3A4
When a combination of amiodarone - inhibitor of the isoenzyme CYP3A4 with these drugs may increase their plasma concentrations, which may lead to an increase in their toxicity and / or increased pharmacodynamic effects and may require a reduction in their doses.
Such drugs include: ciclosporin, fentanyl, inhibitors of HMG-CoA reductase - statins: simvastatin, atorvastatin and lovastatin (the risk of development of rhabdomyolysis during their simultaneous administration with amiodarone increases, if necessary, the administration of statins that are not metabolized with the help of the CYP3A4 isoenzyme); lidocaine (risk of developing sinus bradycardia and neurologic symptoms), tacrolimus (risk of nephrotoxicity), sildenafil, midazolam, triazolam, dihydroergotamine, ergotamine, colchicine.
Drugs that are a substrate isoenzyme CYP2D6 and CYP3A4
Dextromethorphan - amiodarone inhibits the isoenzymes CYP2D6 and CYP3A4 and can theoretically increase the plasma concentration of dextromethorphan.
Clopidogrel, which is an inactive thienopyrimidine drug metabolized in the liver with the formation of active metabolites. Possible interaction between clopidogrel and amiodarone, which can lead to a decrease in the effectiveness of clopidogrel.
Medications, which are substrates of the isoenzyme CYP2S9
Amiodarone increases the concentration in the blood of drugs that are substrates of the isoenzyme CYP2C9, for example, warfarin or phenytoin.
Warfarin - when combined with amiodarone, an increased risk of bleeding may occur. It should be more often (both during treatment with amiodarone and after stopping its administration) to monitor prothrombin time (by determining the International Normalized Ratio) and, if necessary, adjust the dosage regimen.
Phenytoin - when combined with amiodarone, the development of an overdose of phenytoin may occur, which may lead to the appearance of neurologic symptoms; Clinical monitoring is necessary and, at the first signs of an overdose, a decrease in the dose of phenytoin. It is desirable to determine the concentration of phenytoin in the blood plasma.
Medications, which are substrates of the isoenzyme CYP2D6
Flecainide - amiodarone increases its plasma concentration, in connection with which a correction of the doses of the latter is required.
Medications, which are substrates of P-gp Amiodarone is an inhibitor of P-gp, co-administration with drugs that are substrates of P-gp may cause an increase in systemic exposure of the latter.
Cardiac glycosides (digitalis preparations) - possibly as a pharmacodynamic interaction - a decrease in automatism (pronounced bradycardia) and AV conduction, and pharmacokinetic - with the combined administration of digoxin with amiodarone, an increase in the concentration of digoxin in the blood plasma is possible (due to a decrease in its clearance, it is necessary to control the concentration of digoxin in the blood and timely detection clinical manifestations of digitalis intoxication).You may need to reduce the dosage of digoxin.
Dabigatran - caution should be exercised with the simultaneous use of amiodarone with dabigatran because of the risk of bleeding. Dabigatran dose may need to be adjusted in accordance with the instructions in its instructions for use.
The effect of other drugs on amiodarone
Inhibitors of isoenzymes CYP3A4 and CYP2C8 can inhibit the metabolism of amiodarone and increase its concentration in the blood and, accordingly, enhance its pharmacodynamic actions (including, causing the development of side effects).
It is recommended to avoid the simultaneous administration of amiodarone and inhibitors of the isoenzyme CYP3A4, for example, grapefruit juice and some medicines, such as cimetidine, and HIV protease inhibitors (incl. indinavir). Inhibitors of HIV protease when used with amiodarone may increase the concentration of the latter in the blood.
Inductors of the isoenzyme CYP3A4
Rifampicin is a strong inducer of the isoenzyme CYP3A4, when combined with amiodarone, plasma concentrations of amiodarone and desethylamiodarone may decrease.
Preparations of St. John's Wort are a strong inducer of the isoenzyme CYP3A4. In this regard, we can expect a decrease in plasma concentrations of amiodarone and a decrease in its effect (no clinical data are available).