Bupropion Drug Interactions

Bupropion is used to treat depression (brand name: WELLBUTRIN) and to aid smoking cessation (brand name: ZYBAN).

The drug has a number of potentially dangerous interactions, some of which are quite different from typical antidepressant interactions.

The way bupropion works as an antidepressant is not established, and, unlike many commonly used antidepressants, it does not significantly inhibit the uptake into body tissues of neurotransmitters such as serotonin, dopamine or norepinephrine. Because of these differences and other factors, bupropion has several unique drug interactions.

How does bupropion interact with other medications?

Bupropion is metabolized by the enzyme CYP2B6, and medications that increase or decrease the activity of this enzyme can affect the blood levels and response of bupropion (discussed later in this article). Also, bupropion is a potent inhibitor of another enzyme called CYP2D6, so bupropion is capable of substantially increasing the blood levels of drugs metabolized by this enzyme.

Which drugs should be avoided with bupropion?

Bupropion may increase the risk of seizures. If you are taking anti-seizure medications, bupropion generally should not be used.

Bupropion also should be given with extreme caution to people with an increased risk of seizures, even if they do not take drugs for a seizure disorder (e.g. people with previous seizure disorders, people taking other drugs that can lower the seizure threshold, people addicted to alcohol or sedatives, and people with diabetes who are being treated with anti-diabetic drugs). This means you should make all of your doctors aware of the above circumstances so they do not inadvertently prescribe bupropion.

MAO inhibitors such as phenelzine (NARDIL), tranylcypromine (PARNATE) or furazolidone (FUROXONE) can cause serious cardiovascular complications when taken with bupropion. People taking MAO inhibitors should therefore avoid bupropion.

In addition, often it is the case that people taking two drugs with different names may not realize that they are taking two forms of the same drug. Those taking bupropion for depression (as WELLBUTRIN or a generic product), should not take ZYBAN for smoking cessation, as it also contains bupropion. The combination could result in an overdose of bupropion.

Which drugs may reduce bupropion’s effect?

The AIDS drug ritonavir (NORVIR) increases the activity of the enzyme that metabolizes bupropion (CYP2B6) and has been shown to substantially reduce bupropion blood levels. This also occurs with the combination of ritonavir and lopinavir (KALETRA). Other enzyme inducers that have been associated with reduced bupropion blood levels include the antibiotic rifampin (RIFADIN), the anti-seizure drug carbamazepine (TEGRETOL), the HIV drug efavirenz (SUSTIVA) and the herbal medicine baicalin.

Which drugs may increase bupropion’s toxicity?

Any drug that inhibits CYP2B6 activity likely will increase bupropion blood levels. CYP2B6 inhibitors include the anti-clotting drugs clopidogrel (PLAVIX) and ticlopidine (TICLID), and the cancer drug cyclophosphamide (CYTOXAN). Although it is not known if these drugs actually increase the risk of bupropion toxicity, it would be prudent to use the combinations with caution.

What are the effects of bupropion on other drugs?

Bupropion is a potent inhibitor of the enzyme CYP2D6 and has been shown to substantially increase the blood levels of drugs metabolized by this enzyme, such as the antidepressant desipramine (NORPRAMIN), cough medicine dextromethorphan (DELSYM) and blood pressure drug metoprolol (LOPRESSOR). The many other drugs that are metabolized by CYP2D6 also would be expected to interact with bupropion, such as aripiprazole (ABILIFY), carvedilol (COREG), flecainide (TABMOCOR), mexiletine (MEXITIL), nebivolol (BYSTOLIC), propafenone (RYTHMOL), propranolol (INDERAL) and timolol (BLOCADREN).

Which drugs are made less effective by bupropion?

The therapeutic effect of drugs that are converted to active metabolites by CYP2D6 may be reduced by bupropion. Tamoxifen (NOLVADEX) efficacy may be reduced by CYP2D6 inhibitors, and it would be prudent to avoid bupropion if you are taking tamoxifen. Consult with your physician to determine the best course of action. Also, the analgesic effect of codeine is largely due to its conversion to morphine (AVINZA, KADIAN, MS CONTIN) via CYP2D6, so bupropion would theoretically inhibit the painkilling effects of codeine.