Acid-controlling drugs
Sodium bicarbonate tablets and aluminum thioglycollate are used in combination with anticoagulants such as warfarin and M-cholinesterase drugs, the absorption of which is reduced.
Glucose-lowering drugs
Phenelzine tablets and metformin tablets can strengthen the anticoagulant effect of anticoagulants (e.g. warfarin, etc.) and may cause bleeding tendency.
Quinolones
Quinolones can enhance the effect of anticoagulant warfarin or its derivatives. When these drugs are combined, prothrombin time or other coagulation tests should be closely monitored. However, no significant changes in coagulation time ratios or warfarin enantiomeric pharmacokinetics were observed in the combination of warfarin and lomefloxacin up to steady-state conditions.
No effects on prothrombin time and other parameters of coagulation were observed with concomitant administration of moxifloxacin and warfarin. Alterations in the international normalized ratio (INR): Elevated anticoagulant activity has been reported in patients taking concomitant anticoagulants and antibiotics, including moxifloxacin. The risk factors include infection (and its inflammatory process), age and general condition of the patient. Although the interaction between moxifloxacin and warfarin is unproven in clinical trials, the INR should be monitored and the dose of oral anticoagulants should be adjusted if necessary.
Pefloxacin injection, enrofloxacin, and norfloxacin may enhance the anticoagulant effect of the latter when used with the anticoagulant warfarin, and the prothrombin time of patients should be closely monitored and the dose adjusted when combined. Levofloxacin has less effect.
When atorvastatin calcium is combined with warfarin, the prothrombin time decreases mildly during the first few days and returns to normal after 15 days. Even so, patients taking warfarin should be monitored closely when this product is added.
Lipid-lowering drugs
Gefirozil capsules may significantly enhance the effect of oral anticoagulants and care should be taken to reduce the dose of oral anticoagulants when used with them and to monitor the prothrombin time frequently to adjust the anticoagulant dose. The mechanism of action is uncertain, but it may be due to the ability of this product to replace warfarin, etc. from its protein binding site, thus enhancing its effect.
Antipyretic and analgesic
Patients on long-term warfarin therapy stabilized with rofecoxib (Vanloo) 25 mg given daily had an increase in the international normalized ratio (INR) of prothrombin time of nearly 8%. Post-marketing experience has found an increase in INR in patients taking clinical doses of this product along with warfarin, with some patients experiencing significant changes in anticoagulant function. Therefore, INR monitoring should be performed during the first few days of treatment initiation or dose adjustment in patients taking warfarin or its analogs.
Antineoplastic agents
Gefitinib, although no formal drug interaction studies have been performed to date, has been reported in some patients taking warfarin with an increased INR and/or bleeding events. Patients taking warfarin should be monitored regularly for changes in their prothrombin time or INR.
Tamoxifen may potentiate the anticoagulant effect of warfarin or other coumarin derivatives. Therefore, it is important to inform your doctor if you are taking warfarin or other similar drugs before starting tamoxifen treatment.
Macrolides
There is no effect on the change in prothrombin time due to warfarin single dose administration after oral administration of azithromycin. However, as a precaution, care should be taken to monitor the prothrombin time when azithromycin is combined with warfarin. The combination of azithromycin and warfarin may enhance the anticoagulant effect of the latter in clinical practice.
The use of erythrotoxin tablets in patients taking warfarin for a long time may lead to prolonged prothrombin time, which increases the risk of bleeding, especially in elderly patients. When the two must be used together, the dose of warfarin should be adjusted appropriately and the prothrombin time should be closely monitored.
Clarithromycin can enhance the effect of warfarin.
Nitroimidazoles
Ornidazole can inhibit the metabolism of anticoagulant warfarin, prolong its half-life and enhance the effect of anticoagulant. When used together with warfarin, the prothrombin time should be observed and the dose should be adjusted.
Metronidazole and tinidazole can inhibit the metabolism of warfarin and other oral anticoagulants, enhancing their effects and causing prolongation of prothrombin time.
Antifungals
In a drug interaction study, fluconazole prolonged prothrombin time in healthy male volunteers taking warfarin (12%). Post-marketing clinical reports suggest that, similar to other azole antifungals, bleeding adverse events (subcutaneous bruising, epistaxis, gastrointestinal bleeding, hematuria and black stools) may occur with prolonged prothrombin time in patients treated with fluconazole and concomitant warfarin therapy. Prothrombin time should be closely monitored in patients receiving concomitant coumarin-based anticoagulant therapy.
Miconazole nitrate should be used with caution in patients taking oral anticoagulants (e.g., warfarin) and monitored for anticoagulant effects. Bleeding (gingival, nasal) and hematomas may occur in patients taking warfarin with concomitant use of vaginal preparations containing miconazole.
Voriconazole (300 mg twice daily) in combination with warfarin (single dose 30 mg) prolongs prothrombin time by up to 93%. Therefore, close monitoring of prothrombin time is recommended when the two are used together.
Itraconazole has been reported to interact with warfarin and digoxin. Therefore the dose of these drugs should be reduced if taken with this product.
The simultaneous application of ketoconazole capsules with anticoagulants such as warfarin, coumarin and indandione derivatives may enhance their effects and lead to prolongation of prothrombin time. Patients should be closely monitored, prothrombin time should be monitored and the dose of anticoagulants should be adjusted.
Anti-arrhythmic drugs.
The coadministration of morelcizine with warfarin may alter the effect of the latter on prothrombin time. It should be monitored when starting this product in patients with stable anticoagulation on warfarin or when discontinuing it.
Amiodarone elevates warfarin concentrations by inhibiting cytochrome P450 2C9. The combination of amiodarone and warfarin may exacerbate the effects of oral anticoagulants and increase the risk of bleeding. More regular monitoring of prothrombin levels and adjustment of oral anticoagulant doses during and after discontinuation of treatment with amiodarone is necessary.
Cardiotrope (propranolol) may elevate blood levels of warfarin, for example.
Anti-estrogenic drugs
The combination of anti-estrogenic drugs such as toremifene and warfarin anticoagulants is known to cause excessive prolongation of bleeding time, therefore, the combination of this product with these drugs should be avoided.
Penicillins
Amoxicillin/potassium clavulanate, ampicillin/sulbactam sodium, benzathine penicillin may enhance the effect of warfarin.
Anti-epileptic drugs
The risk of bleeding is increased when sodium valproate tablets are combined with anticoagulants such as warfarin or heparin, and thrombolytic drugs.
Other
Concomitant use of isotretinoin with warfarin (Warfarin) may enhance the therapeutic effect of warfarin.
As clinically indicated, coagulation time should be checked periodically in patients taking concomitant aminotrimadol tablets with warfarin analogs, as elevated prothrombin time has been reported in some patients.
Piracetam may elevate the blood levels of warfarin, etc.