Medications for Obesity: Naltrexone/Bupropion

 

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Updated September 12, 2014.
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On September 10, 2014, the U.S. Food and Drug Administration (FDA) approved a new medication for the treatment of obesity. The medication, known by the brand name Contrave® and marketed by Takeda Pharmaceuticals, is a combination of two other drugs, naltrexone hydrochloride and bupropion hydrochloride.

For Whom Is Naltrexone/Bupropion Intended?

According to the FDA news release of September 10, 2014, this new drug is approved for use in adult patients with a body mass index (BMI) of 30 or greater, or in adult patients with a BMI of 27 or greater who have at least one weight-related condition (such as high blood pressure, high cholesterol, obstructive sleep apnea, or Type 2 diabetes).

As noted by the FDA, this medication is meant to be a “treatment option for chronic weight management in addition to a reduced-calorie diet and physical activity.” It is not meant to replace lifestyle changes that include a healthy diet and exercise.

What Is Naltrexone/Bupropion?

What kind of drug is naltrexone/bupropion? It is a fixed-dose combination of two medications: naltrexone, which is an opioid receptor antagonist and has been used for many years primarily for the management of alcohol and/or opioid dependence; and bupropion, which has been and continues to be used for the treatment of depression as well as for smoking cessation. This fixed-dose combination is in an extended-release formulation as Contrave®.

How Effective Is It?

Multiple clinical trials were conducted to evaluate the effectiveness of the naltrexone/bupropion fixed-dose combination now known as Contrave®. These trials included approximately 4,500 obese and overweight individuals over the course of one year. In one clinical trial, patients had an average weight loss of 4.1% more when taking Contrave® (when compared to placebo; all patients received lifestyle modification that included a reduced-calorie diet and regular physical activity). This trial also found that 42% of the patients who were taking Contrave® lost at least 5% of their body weight, compared to 17% of patients who did the same while taking placebo.

In another clinical trial that looked at patients who were obese or overweight and also had Type 2 diabetes, those who took Contrave® were found to have an average weight loss of 2% more than placebo at one year. This trial also found that 36% of the patients who were treated with Contrave® lost at least 5% of their body weight, compared to 18% of patients treated with placebo.

It is worth noting that the percentage of patients in these trials who lost weight on placebo was still substantial—meaning that dietary and physical activity modifications, known as “lifestyle changes,” do make a difference.

Further, the FDA states that Contrave® should be discontinued if a patient has not lost at least 5% of baseline body weight after 12 weeks on the drug.

Black Box Warning

The FDA has given Contrave® a black box warning because it contains bupropion. This warning notes that there can be an increased risk of suicidal thoughts and behaviors associated with antidepressant drugs, including bupropion. The warning also notes that “serious neuropsychiatric events have been reported in patients taking bupropion for smoking cessation.”

Possible Side Effects

Common side effects reported during the clinical trials with Contrave® included nausea, vomiting, constipation, diarrhea, headache, dizziness, insomnia and dry mouth.

The FDA’s news release noted that Contrave® can cause seizures and should therefore not be used in patients with seizure disorders. Another serious potential side effect is the possibility of an increase in blood pressure and heart rate on Contrave®; for this reason, the medication is contraindicated in patients with uncontrolled high blood pressure. Blood pressure and pulse should be monitored while a patient is taking Contrave®. In addition, other products containing bupropion should not be taken along with Contrave®.

Because of its naltrexone component, Contrave® is also contraindicated in patients who are taking opioids or who are being treated for opioid dependence. Patients who are abruptly discontinuing benzodiazepines, alcohol, barbiturates, or antiepileptic drugs should also not take Contrave®.

Contrave® is also contraindicated in women who are pregnant or trying to become pregnant.

_References:

_{U.S. Food and Drug Administration. FDA approves weight-management drug Contrave. Accessed online at http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm413896.htm on September 11, 2014.}