Sibutramine
A serotonin-noradrenaline reuptake inhibitor marketed as Meridia/Reductil for weight loss from 1997. It produced modest, sustained weight loss but was withdrawn worldwide around 2010 after the SCOUT trial showed increased non-fatal heart attacks and strokes. It remains a common illegal adulterant in 'herbal' slimming products.
01 Overview
Sibutramine (and its active metabolites) inhibits reuptake of serotonin and noradrenaline, reducing appetite and modestly increasing energy expenditure. In trials it delivered roughly 3-5 kg more weight loss than placebo over a year, and it was widely prescribed for a decade.
The SCOUT (Sibutramine Cardiovascular Outcomes) trial in high-risk patients found a significant increase in non-fatal myocardial infarction and stroke, prompting EMA and FDA withdrawal in 2010. It is now banned as a medicine in most countries but is repeatedly detected illegally spiked into weight-loss supplements, causing avoidable cardiovascular harm.
02 Mechanism
Inhibits reuptake of serotonin and noradrenaline (and weakly dopamine) centrally, enhancing satiety and thermogenesis; raises heart rate and blood pressure as a class effect.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Former therapeutic dose | 10–15 mg/day | Oral | 10 mg once daily, titratable to 15 mg; withdrawn from market. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Sustained weight lossModest but durable weight loss with satiety enhancement and mild thermogenesis. | ~3-5 kg vs placebo/year | Clinical | |
| Improved glycaemic and lipid markersSecondary metabolic improvements accompanying weight loss. | small | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Increased cardiovascular eventsSignificant excess of non-fatal myocardial infarction and stroke in high-risk patients, the reason for worldwide withdrawal. | Severe | Increased vs placebo (SCOUT) | Clinical | |
| Hypertension and tachycardiaDose-related rise in blood pressure and pulse. | Moderate | Common | Clinical |