Sibutramine
Obesity drug withdrawn from the EU market in 2010
Sibutramine was a centrally acting serotonin and noradrenaline reuptake inhibitor that was prescribed in Germany between 1999 and 2010 as an obesity drug under the brand name Reductil. Following evaluation of the SCOUT trial, the EMA withdrew European approval of the substance in January 2010 because the risk of cardiovascular events clearly outweighed the benefit of weight reduction. The United States and other countries followed with market withdrawals shortly afterwards.
Although sibutramine has not been authorised in the EU for more than 15 years, the substance remains relevant because it still appears illegally in counterfeit slimming products from the internet, beauty salons or foreign sources. Consumers often believe they are buying a herbal or harmless slimming product but actually receive sibutramine containing preparations in sometimes considerable doses. BfArM regularly warns against such products. This page provides information from a medical and consumer protection perspective on action, risks and warnings.
Mechanism of Action
Sibutramine inhibits presynaptic reuptake of serotonin and noradrenaline and, to a lesser extent, dopamine. The increased central availability of these neurotransmitters acts on satiety centres in the hypothalamus, reducing appetite and enhancing satiety. Combined with a calorie restricted diet, sibutramine led in clinical trials to an additional weight reduction of 2 to 5 kilograms over 12 months compared with placebo.
The peripheral activity of the substance is based on sympathomimetic effects. Heart rate, arterial blood pressure and oxygen consumption rise. In patients with pre existing cardiovascular disease or cardiovascular risk factors, this potentiates the risk of myocardial infarction, stroke and cardiac death. This very observation led to the SCOUT trial and ultimately to market withdrawal.
The half life of active metabolites was about 14 to 16 hours, enabling once daily dosing of 10 or 15 mg. Metabolism took place mainly via CYP3A4. CYP3A4 inhibitors such as ketoconazole could raise plasma levels and thereby the unwanted effects.
Market Withdrawal 2010
The SCOUT trial (Sibutramine Cardiovascular OUTcomes Trial), published in 2010, investigated sibutramine in approximately 10000 obese high risk patients aged 55 to 74 years with cardiovascular pre existing conditions or multiple risk factors. The primary endpoint analysis showed, under sibutramine, a significantly increased risk of non fatal myocardial infarction and non fatal stroke of about 16 percent compared with placebo. Weight reduction under sibutramine averaged an additional 1.7 kg over placebo, which was judged clinically insufficient.
The EMA concluded that cardiovascular risk outweighed the modest weight effect and withdrew the authorisation across Europe in January 2010. The FDA followed in October 2010. As a consequence, sibutramine products were recalled from pharmacies. Regular prescription has not been possible in the EU since 2010.
The lesson from the sibutramine case is a stricter approach to the approval of obesity drugs: cardiovascular safety studies have since become obligatory before a weight reduction drug is used broadly. Modern substances such as liraglutide, semaglutide and tirzepatide have shown cardiovascular benefits rather than risks in such studies and have reshaped the therapeutic landscape.
Side Effects
Common to very common: dry mouth, insomnia, headache, constipation, decreased appetite (intended and unwanted), anxiety and irritability, tachycardia, blood pressure rise, sweating, taste changes.
Uncommon to rare: palpitations, hypertension, vomiting, haemorrhoids, cycle disturbances, sexual dysfunction, paraesthesia, depression, concentration problems.
Serious: myocardial infarction, stroke, severe hypertension, arrhythmia, serotonin syndrome on combination with serotonergic substances, pulmonary hypertension, liver failure, seizures, suicidality.
Combination hazards: concomitant use with MAO inhibitors or other serotonergic substances (SSRI, SNRI, tramadol, linezolid, triptans) can trigger a life threatening serotonin syndrome. In illegal counterfeit products this warning is not visible; consumers often do not realise they are taking sibutramine.
Risk of Counterfeit Slimming Products
Despite EU wide withdrawal, sibutramine regularly turns up in counterfeit or illegally traded slimming preparations that are marketed as herbal, homeopathic or as food supplements. BfArM and EMA issue regular warnings about specific products. Internet offers, beauty studios and products brought from abroad are particularly affected.
Such preparations often contain unknown, variable and potentially very high doses of sibutramine, sometimes combined with sildenafil, phenolphthalein, diuretics or thyroid hormones. Uncontrolled intake has in individual cases led to myocardial infarctions, strokes, severe psychiatric side effects and deaths. Detection of illegal admixture succeeds only through forensic chemical analysis.
Typical warning signs for consumers are promises of extreme weight loss without dieting, opaque ingredient lists, orders from abroad without a German package leaflet and the appearance of side effects such as palpitations, insomnia and dry mouth after taking an allegedly herbal product. With such symptoms the product should be stopped immediately and a physician consulted. Leftovers of the product should be kept for possible analysis.
Today's Alternatives
- Orlistat: lipase inhibitor, reduces fat absorption by about 30 percent, available over the counter and by prescription
- Liraglutide (Saxenda): GLP 1 receptor agonist as subcutaneous injection, clinically relevant weight reduction
- Semaglutide (Wegovy): GLP 1 receptor agonist as weekly subcutaneous injection, marked weight reduction in the STEP studies
- Tirzepatide (Mounjaro, Zepbound): dual GIP and GLP 1 receptor agonist, even stronger action
- Naltrexone plus bupropion (Mysimba): combination product with moderate effect, Dear Doctor letter in 2015 concerning cardiovascular effects
- Bariatric surgery: for severe obesity with BMI from 35 plus comorbidity or from 40 without comorbidity
- Structured lifestyle programmes: dietary change, exercise and behavioural therapy as the foundation of every obesity therapy
Special Notes
No prescription in the EU: sibutramine is no longer authorised in the European Union. Physicians must not prescribe the substance and pharmacies must not dispense it. Imports from third countries without valid approval are illegal and carry considerable risks. A medical indication for sibutramine no longer exists according to current evidence.
Suspicion of sibutramine intake: in patients with unexplained rise in blood pressure, tachycardia, insomnia, weight loss and use of slimming products from dubious sources, a detailed history and, where appropriate, toxicological analysis are sensible. The substance and its metabolites can be detected in urine.
Pregnancy and lactation: sibutramine was always contraindicated in pregnancy and lactation. In suspected sibutramine intake, seek medical clarification without delay.
Prevention: obesity therapy belongs in medical hands. Nutritional counselling, behavioural therapy and approved, proven medications are effective and safe. For every internet or beauty studio product, the first question is who the manufacturer and distributor are and whether EU approval exists. Over the counter is not the same as safe.
Suspected counterfeit: do not continue to take the product, seek medical clarification, notify BfArM via the ADR reporting form or via nebenwirkungen.bund.de. The report helps protect other consumers.
You Might Also Be Interested In
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- Atorvastatin, statin in cardiovascular prevention
- Ertugliflozin, SGLT 2 inhibitor with weight reduction
Frequently Asked Questions
Why was sibutramine banned?
The SCOUT trial showed an increased risk of heart attack and stroke in patients with cardiovascular background risk, while the weight effect was only modest. In 2010 the EMA concluded that the modest benefit did not justify the risk and withdrew the authorisation. Since then sibutramine can no longer be prescribed in the EU.
I bought a slimming product online and feel my heart racing, what should I do?
Stop taking it immediately, keep the product and packaging, seek medical clarification. With severe symptoms (strong palpitations, chest pain, shortness of breath, confusion) call the emergency number 112 immediately. Notify BfArM via the ADR reporting portal to protect other consumers.
Are there safe drugs for weight reduction?
Yes. Orlistat acts locally in the gut and has been established for years. Modern GLP 1 receptor agonists such as liraglutide, semaglutide and tirzepatide show marked weight reductions and have provided cardiovascular safety signals in long term trials. Prescription belongs in medical hands, and the effect is greatest in combination with lifestyle change.
Can I buy sibutramine abroad?
Import without valid authorisation is illegal and carries significant health risks. Products from abroad may be contaminated, underdosed or overdosed. The EMA withdrew sibutramine for good reasons; approved alternatives are safer and often even more effective.
Sources
- EMA, European Medicines Agency, Sibutramine market withdrawal 2010
- BfArM, warnings on illegal slimming products
- Nebenwirkungen.bund.de, ADR reporting portal
- AWMF, S3 Guideline Prevention and Therapy of Obesity
Legal Notice and Disclaimer
The information provided on this page is for general informational purposes only and does not constitute medical advice, diagnosis or treatment recommendation. It does not replace consultation with a licensed physician or pharmacist. Medicines should only be taken on medical prescription or via a pharmacy. All information is based on product information and recognised scientific sources published at the time of creation; the manufacturer's current summary of product characteristics is always authoritative. Sanoliste assumes no liability for the completeness, timeliness or accuracy of the information presented. In a medical emergency, call the emergency number 112 (Europe).