AIDS and HIV Information
Atripla and Grapefruit: Interactions and How to Deal with It
Grapefruit can be an excellent part of your diet. It’s rich in Vitamin C, potassium, and other nutrients that your body needs to function properly. It also contains flavonoids that have a preventive impact on chronic diseases, such as cancer and heart problems. But grapefruit and even commercially available grapefruit juice can pose as a health risk when taken with some medications. Patients must be educated of its effects on their medications since the juice and drugs are often consumed together at breakfast.
There are more than 85 drugs that can interact with grapefruit, and it includes HIV meds like Atripla. The chemical component of grapefruit interacts with the efavirenz content of Atripla. Not surprisingly, since efavirenz (Sustiva) must be taken with an empty stomach. It has been demonstrated that the body absorbs more of the drug after a meal, which can increase the occurrence of side effects.
Grapefruit alters drug levels
The unprecedented discovery that grapefruit juice can significantly affect the oral bioavailability of some drugs was actually a serendipitous finding. A group of Canadian researchers, Bailey and colleagues, were conducting an interaction study between the calcium channel blocker felodipine and ethanol. The team used grapefruit juice to mask the taste of ethanol. Felodipine is a drug used to treat high blood pressure. The authors wanted to know if alcohol interacts with the drug, but they also came up with an unexpected observation: grapefruit dramatically increases the drug levels in the blood. In fact, the first report of the interaction stated that compared to water, grapefruit juice tripled the mean plasma levels of felodipine. While it increases the blood pressure reduction capability of the drug, it also increases heart rate and frequency of vasodilation-related side effects. This is particularly worrying because the effects of grapefruit lasts for about 24 hours or more. The fruit can also decrease the amount of drugs in the body, including anti-allergy drugs like Allegra (fexofenadine). Other drugs that may interact with grapefruit juice include:
- Anxiolytic medications – Xanax (alprazolam) and Halcion (triazolam);
- Antibiotic medications – erythromycin and clarithromycin;
- Blood pressure medications – Plendil (felodipine), Covera-HS (verapamil), Cozaar (losartan);
- Antiarrhythmic drugs – Cordarone (amiodarone), Multaq (dronedarone);
- HIV medications – Crixivan (indinavir), Invirase (saquinavir);
- Cancer medications – Tasigna (nilotinib), Votrient (pazopanib).
Primary mechanism of grapefruit-drug interaction
Out of 85 or so prescription medications that can be affected by grapefruit intake, 43 of which can cause life-threatening interactions. A single glass (250ml) of grapefruit juice is enough to alter drug metabolism, and the effects may last up to three days. Most drugs are commonly metabolized in the liver. The CYP3A4 enzyme contributes in the metabolism of more than half of all medications. Before the drug components enter the system, the enzyme can either inactivate them for elimination or, in the case of prodrugs, they are metabolized to more active forms.
Grapefruit juice contains furanocoumarins; these compounds bind irreversibly to CYP3A4 enzyme in the small intestine and inactivates it, resulting into an increased amount of oral medication delivered in systemic circulation. The juice, however, does not affect medications administered intravenously. The efavirenz in Atripla is metabolized by the enzymes CYP2B6 and CYP3A4—members of the cytochrome P 450 (CYP) enzyme system. Taking grapefruit with Atripla can increase the amount of efavirenz in your bloodstream, which can increase the likelihood of side effects. This regimen must be taken on an empty stomach, which means an hour before meal, or two hours after you’ve eaten. Grapefruit is not covered by this recommendation since its effects can last for days.
Dealing with grapefruit-drug interactions
- Before taking HIV drugs and other prescription medications, read the patient information sheet or the drug facts label of OTC drugs to know if grapefruit juice affects your medication.
- Ask your healthcare provider, pharmacist, or nurse if you can take your medication together with grapefruit.
- Always check the labels of fruit juices or fruit-flavored food and drinks if they are made with grapefruit juice.
- Similar fruits, such as Seville oranges, tangelos, and pomelos, may have the same effect as grapefruit juice. Avoid these fruits if your medication interacts with grapefruit.
- The effect of grapefruit may take days, so it’s not enough to avoid taking it at the same time as your medicine. You need to avoid it the whole period that you are on the regimen.
- Inform your doctor if you have taken significant amount of grapefruit with Atripla or if you can’t avoid consuming the fruit.