Another asked
I work in a memory care facility and we have a patient who's medication we are allowed to crush. The thing is that chocolate pudding is not working anymore. Would the medication lose its effect or get affected in anyway if I crushed the pills and pour them into cranberry juice?
Answer
Cranberry juice has the potential to interact with many different medications and is therefore generally not recommended to be administered at the same time. However, more data and research are needed to accurately identify exactly what cranberry interacts with and how severe the potential drug interactions are. Below, we list some potential interactions between cranberry (and cranberry juice) with medication.
Cranberry Medication Interactions
Cranberry is thought to inhibit a various CYP metabolizing enzymes in the liver including:
- CYP3A4
- CYP2C9
Inhibition of metabolizing enzymes, in most cases, will decrease how quickly drugs are metabolized, potentially increasing drug concentrations in the body, increasing the risk of side effects.
In addition, cranberry may also inhibit OATP (Organic-anion-transporting polypeptide), an important transport enzyme responsible for transporting certain drugs into cells. Without OATP, drugs may have less of an effect. A classic example of this interaction is with the antihistamine Allegra (fexofenadine). The labeling recommends avoiding co-administration of Allegra with citrus (which can inhibit OATP) since the drug will be significantly less effective.
Cranberry CYP3A4 Drug Interactions
Cranberry has several documented interactions with two drugs metabolized by CYP3A4:
- Lipitor (atorvastatin)
- Nifedipine
One case study reported symptoms of rhabdomyolysis, and abnormal liver function in a patient taking Lipitor (atorvastatin) in combination with cranberry juice (16 ounces daily for 2 weeks). All lab values and liver enzymes returned to normal within 2 weeks of stopping cranberry juice.
An animal study showed that cranberry juice inhibits the metabolism of the drug nifedipine and significantly increases total concentrations of the drug in the body, which could potentially lead to serious adverse reactions.
CYP3A4 is one of the major metabolizing enzymes in the body. Although there isn't data on whether or not cranberry interacts with all medications metabolized by this enzyme, there is still the potential for it and caution is advised administering cranberry with these medications. Medications metabolized by CYP3A4 include:
- Lovastatin
- Ketoconazole
- Itraconazole
- Triazolam
- Clarithromycin
- Fluconazole
- Various chemotherapy drugs
- Trazodone
Cranberry CYP2C9 Drug Interactions
Cranberry may also inhibit CYP2C9, but evidence is conflicting. Lab studies show that cranberry does inhibit CYP2C9 to some extent, but studies in humans haven't shown any significant effect. Nevertheless caution would be advised when administering cranberry with drugs metabolized by CYP2C9, which include:
- Amitriptyline
- Diazepam
- Warfarin
- Celecoxib
- Diclofenac
- Fluvastatin
- Glipizide
- Ibuprofen
- Irbesartan
- Losartan
- Phenytoin
- Piroxicam
One particular drug of note is warfarin. There is contradictory evidence about the effect of drinking cranberry juice on warfarin. There are several published case reports of cranberry interacting with warfarin, causing an increase in INR and bleeding episodes. Other studies however are dubious that the interaction exists or is clinically relevant to most individuals.
Conclusion
Cranberry juice may interact with various medications via inhibition of liver metabolizing enzymes (which can increase drug concentrations) and inhibition of transport enzymes (which can decrease drug concentrations). Complete data is sparse, but based on what we do know of potential drug interactions, cranberry typically isn't a good choice to administer at the same time as your medication.
