Last reviewed · How we verify

NB

Orexigen Therapeutics, Inc · FDA-approved active Small molecule

NB (naltrexone/bupropion) is a combination drug that reduces appetite and increases energy expenditure through opioid antagonism and norepinephrine/dopamine reuptake inhibition.

NB (naltrexone/bupropion) is a combination drug that reduces appetite and increases energy expenditure through opioid antagonism and norepinephrine/dopamine reuptake inhibition. Used for Chronic weight management in obese or overweight adults with weight-related comorbidities.

At a glance

Generic nameNB
SponsorOrexigen Therapeutics, Inc
Drug classCombination antiobesity agent (opioid antagonist + norepinephrine-dopamine reuptake inhibitor)
TargetOpioid receptors (naltrexone); norepinephrine and dopamine transporters (bupropion)
ModalitySmall molecule
Therapeutic areaObesity / Metabolic Disease
PhaseFDA-approved

Mechanism of action

Naltrexone blocks opioid receptors in the hypothalamus, removing tonic inhibition of pro-opiomelanocortin (POMC) neurons that regulate appetite. Bupropion, an atypical antidepressant, inhibits reuptake of norepinephrine and dopamine, further enhancing satiety signaling and metabolic rate. Together, these mechanisms reduce hunger and increase energy expenditure, leading to weight loss.

Approved indications

Common side effects

Key clinical trials

Primary sources

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SourceUsed for
ClinicalTrials.govTrial enrolment, design, endpoints, results