Apixaban Dose Adjustments and Drug Interactions
Apixaban (Eliquis) is a somewhat newer anticoagulant. While it is tempting to utilize the “set it and forget it” mindset with dosing, we must remember that there are a few reasons that we might have to make apixaban dose adjustments.
Apixaban dose adjustments are not very common, but we need to clinically assess this with ongoing therapy. Having a fixed dose is nice as the patient does not need to come in routinely to assess their level of anticoagulation (i.e. warfarin with INR checks). This does go with the assumption that patients are taking their medication routinely. This is not a given and be sure you assess adherence regularly. It is dosed twice daily and I have had numerous patients struggle with evening dosing of medication due to a busy life/work schedule. I won’t get too deep into that in this post, but I wanted to provide few reasons why we might have to use a different dose.
Patients who have 2 out of 3 of these factors.
- Age. Patients who are 80 years old and older
- Poor kidney function. Patients with a creatinine of 1.5 or greater
- Low body weight. Patients who are less than 60 kg.
When studying for exams, I always remember the numbers 80, 60, 1.5. This is a good stimulus for me to remember these factors and make sure the dose is adjusted appropriately. Another tip if you don’t have labs, would be to ask the patient about their diagnosis history (such as, have you had trouble with your kidneys in the past?)
The usual dose of apixaban in atrial fibrillation is 5 mg twice daily. If the patient has two of the above three factors, the apixaban dose should be reduced to 2.5 mg twice daily.
Apixaban Drug Interactions
Apixaban is not free from drug interactions. Fortunately, it doesn’t have a lot of really common drug interactions, but it definitely has some significant ones. If I don’t have a full medication list, I keep my eye open for certain disease states where interacting drugs may be used.
HIV/AIDS medications do have some interactions with apixaban. If you come across a patient needing anticoagulation and is treated with antiretroviral therapy. Look up the interactions. This is what I have to do because I can’t remember them all.
Classic 3A4 inhibitors. Drugs like amiodarone, clarithromycin, cyclosporine, azole antifungals, and diltiazem all have the potential increase concentrations. Be cautious with these and monitor patients for bleed risk closely.
Classic enzyme inducers: Carbamazepine, rifampin, and St. John’s wort can all potentially lower concentrations of apixaban.
This is not an all inclusive list, but I just wanted to give you a sense of some of the medications that might have significant impacts on apixaban concentrations. When you are reviewing what conditions a patient has, look out for AIDS, fungal infections, seizure disorder, and bacterial infections. These are a few conditions where medications that interact with apixaban may be used.
I discuss apixaban further in this recent podcast episode.
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