The use of the following drugs together with clarithromycin is contraindicated in connection with the possibility of developing serious side effects
Cisapride, pimozide, terfenadine, astemizole
With the simultaneous use of clarithromycin with cisapride / pimozide / terfenadine / astemizole, it is possible to increase the concentration of the latter and the blood plasma, which may lead to an increase in the QT interval and the appearance of cardiac arrhythmias, including ventricular tachycardia, ventricular fibrillation, ventricular pirouette tachycardia (see " Contraindications ").
Alkaloids of ergot
With the combined use of clarithromycin with ergotamine or dihydroergotamine, acute poisoning with a group of ergotamines is possible: vascular spasm, ischemia of limbs and other tissues, including the central nervous system. Simultaneous use of clarithromycin and ergot alkaloids is contraindicated (see the section "Contraindications"),
The effect of other drugs on clarithromycin
The following drugs have a proven or suspected effect on the concentration of clarithromycin. In the case of their combined use with clarithromycin, dosage adjustment and the transition to alternative treatment may be required.
Preparations that are inducers of the isoenzyme CYP3A (for example, rifampicin, phenytoin, carbamazepine, phenobarbital, St. John's wort), can induce the metabolism of clarithromycin. This can lead to a subtherapeutic concentration of clarithromycin, which leads to a decrease in its effectiveness. In addition, it is necessary to monitor the concentration of the CYP3A inductor in the blood plasma, which may increase due to inhibition of the CYP3A isoenzyme by clarithromycin.
Efavirenz, nevirapine, rifampicin, rifabutin, rifapentin
Strong inductors of the cytochrome P430 system, such as efavirenz, nevirapine, rifampicin, rifabutin and rifapentin can accelerate the metabolism of clarithromycin and thus, reduce the concentration of clarithromycin in the blood and weaken the therapeutic effect, and at the same time increase the concentration of 14- (R) -hydroxyclarithromycin.
Etravirine
The concentration of clarithromycin decreases with the use of etravirine, but the concentration of the active metabolite 14- (R) -hydroxyclarithromycin increases.
Fluconazole
The simultaneous administration of fluconazole at a dose of 200 mg daily and clarithromycin at a dose of 1 g / day increases the minimum average value of the equilibrium concentration of clarithromycin (Cmin) and the area under the "concentration-time" curve of clarithromycin by 33% and 18%, respectively. Correction of the dose of clarithromycin in the case of concurrent administration of fluconazole is not required.
Ritonavir
Joint intake of ritonavir at a dose of 600 mg / day and clarithromycin 1 g / day leads to a decrease in the metabolism of clarithromycin. With the joint administration of ritonavir, the maximum equilibrium concentration (Cmax) clarithromycin increased by 31%, Cmin increased by 182% and the area under the concentration-time curve increased by 77%. A complete inhibition of the formation of 14- (R) -hydroxyclamirithromycin. In patients with chronic renal failure, dose adjustment is necessary: with creatinine clearance of 30-60 ml / min, the dose of clarithromycin should be reduced by 50%, with a creatinine clearance of less than 30 ml / min by 75%. Doses of clarithromycin exceeding 1 g / day should not be used together with ritonavir.
Oral hypoglycemic drugs / insulin
With the combined use of clarithromycin and oral hypoglycemic agents and / or insulin, pronounced hypoglycemia can be observed.Careful monitoring of glucose level is recommended.
Action of clarithromycin on other drugs
Antiarrhythmic drugs
Possible occurrence of ventricular tachycardia of the "pirouette" type in the joint application of clarithromycin and antiarrhythmic drugs (quinidine, procainamide). With the simultaneous use of clarithromycin with these drugs, the electrocardiogram should be monitored regularly to increase the QT interval, and the serum concentrations of these drugs should be monitored.
Interactions caused by isoenzymes CYP3A
Joint reception of clarithromycin and drugs, primarily metabolized by isoenzymes CYP3A, can enhance or prolong both therapeutic and side effects. Clarithromycin should be used with caution in patients receiving drugs that are substrates of the isoenzyme CYP3A, especially if these drugs have a narrow therapeutic range (for example, carbamazepine), and / or intensively metabolized by this enzyme, if necessary, dose adjustment of the drug taken with clarithromycin should be performed.Also, if possible, monitoring of serum concentrations of drugs that are primarily metabolized by the CYP3A isoenzyme should be conducted.
Inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A-reductase (HMG-CoA reductase) (statins)
Clarithromycin increases the concentration of HMG-CoA reductase inhibitors (eg, lovastatin, simvastatin). The combined use of clarithromycin with lovastatin or simvastatin is contraindicated (see "Contraindications") because these statins are heavily metabolized by the CYP3A4 isoenzyme and co-administration with clarithromycin increases their serum concentrations, which leads to an increased risk of myopathy. If it is necessary to use clarithromycin, you should stop taking lovastatin or simvastatin for the duration of therapy.
Indirect anticoagulants
With the joint administration of warfarin and clarithromycin, bleeding is possible, expressed by an increase in INR and prothrombin time. In the case of combined use with warfarin or other indirect anticoagulants, it is necessary to monitor INR and prothrombin time.
Omeprazole
With simultaneous reception of clarithromycin and omeprazole plasma levels of clarithromycin and its metabolite increase. The concentration of clarithromycin in tissues and gastric mucosa with simultaneous reception is also increased.
Sildenafil, tadalafil, vardenafil
The combined use of clarithromycin with sildenafil, tadalafil or vardenafil (phosphodiesterase 5 inhibitors) may increase the inhibitory effect on phosphodiesterase. You may need to reduce the dose of sildenafil, tadalafil and vardenafil.
Theophylline, carbamazepine
With the combined use of clarithromycin and theophylline or carbamazepine, an increase in the concentration of these drugs in the systemic circulation is possible.
Tolterodin
With the combined use of clarithromycin with tolterodine in patients with a low activity of the CYP2D6 isoenzyme, a dose reduction of tolterodine in the presence of clarithromycin (an inhibitor of the CYP3A isoenzyme) may be required.
Benzodiazepines (e.g., alprazolam, midazolam, triazolam)
With the simultaneous administration of clarithromycin (1 g / day) with midazolam (orally), an increase in the area under the concentration-time curve of midazolam was observed 7-fold.It is necessary to avoid the combined oral administration of clarithromycin and midazolam. When using midazolam (intravenous) and clarithromycin, a dose adjustment may be required.
The same precautions should also be applied to other benzodiazepines that are metabolized by CYP3A isoenzymes, including triazolam, alprazolam. For benzodiazepines, the excretion of which does not depend on the isoenzyme CYP3A (temazepam, nitrazepam, lorazepam), clinically significant interaction with clarithromycin is unlikely.
With the combined use of clarithromycin and triazolam, the central nervous system (CNS) may be affected, for example, drowsiness and confusion. In this regard, in the case of joint application, it is recommended to follow the symptoms of the CNS disorder.
Interaction with other drugs
Colchicine
With the joint administration of clarithromycin with colchicine, the effect of colchicine may be enhanced. It is necessary to monitor the possible development of clinical symptoms of colchicine poisoning, especially in elderly patients and patients with chronic kidney failure (as reported, some cases ended in a fatal outcome).
In patients with normal renal and hepatic function, a dose of colchicine should be lowered with simultaneous use with clarithromycin.
Simultaneous use of clarithromycin and colchicine is contraindicated in patients with impaired liver and kidney function (see section "Contraindications").
Digoxin
Joint reception of digoxin and clarithromycin may lead to an increase in serum digoxin concentration in patients. With the joint administration of clarithromycin and digoxin, the concentration of digoxin in the blood serum should be carefully monitored (possibly increasing its concentration and the development of potentially detailed arrhythmias).
Zidovudine
Simultaneous reception of clarithromycin and zidovudine by adult HIV-infected patients can lead to a decrease in the equilibrium concentration of zidovudine. Because the clarithromycin affects the absorption of zidovudine when ingested, interactions can be largely avoided by taking clarithromycin and zidovudine with an interval of 4 hours.
Phenytoin and valproic acid
When joint application of phenytoin or valproic acid with clarithromycin is recommended to determine their serum concentrations,as there are reports of their increase.
Bi-directional drug interactions
Atazanavir
With the combined use of clarithromycin (1 g / day) and atazanavir (400 mg / day) may lead to a twofold increase in the effect of clarithromycin and a decrease in the effect of 14- (R) -hydroxyclamirithromycin by 70%, with an increase in the area under the concentration-time curve of atazanavir by 28%.
In patients with normal renal function, a decrease in the dose of clarithromycin is not required.
In patients with moderate renal insufficiency (creatinine clearance 30-60 ml / min), the dose of clarithromycin should be reduced by 50%.
In patients with creatinine clearance less than 30 ml / min, the dose of clarithromycin should be reduced by 75%. Clarithromycin in doses exceeding 1 g / day, can not be used in conjunction with protease inhibitors.
Blocks of "slow" calcium channels
With simultaneous use of clarithromycin and blockers of "slow" calcium channels that are metabolized by the CYP3A isoenzyme (for example, verapamil, amlodipine, diltiazem), you should be careful, since there is a risk of arterial hypotension.Plasma concentrations of clarithromycin as well as blockers of "slow" calcium channels can increase with simultaneous application. Arterial hypotension, bradyarrhythmia and lactic acidosis are possible with concurrent administration of clarithromycin and verapamil.
Itraconazole
With the joint administration of clarithromycin and itraconazole, a mutual increase in the concentration of drugs in the plasma is possible. Patients simultaneously taking itraconazole and clarithromycin, should be carefully examined for signs of increased or prolonged pharmacological effects of these drugs.
Saquinavir
With concurrent administration of clarithromycin (1 g / day) and saquinavir (in soft gelatin capsules, 1200 mg 3 times a day), an increase in the area under the concentration-time curve and Cmax saquinavir by 177% and 187%, respectively, and clarithromycin by 40%. If these two drugs are used together for a limited time in the doses indicated above, dose adjustment is not required.