Table 1.
Characteristics of pharmacological agents currently licensed for long-term weight loss
| Drug | Dosage | Mechanism of action | Placebo-subtracted weight loss in phase 3 trials | Key adverse effectsa | Contraindications |
|---|---|---|---|---|---|
| Orlistat (Xenical) | 120 mg three times daily (immediately before, during or after meals) | Intestinal lipase inhibitor | 3.0 % [46] | Common/mild: oily stools, malabsorption of fat-soluble vitamins (multivitamins are recommended) Rare/severeb: may reduce absorption of some medications such as ciclosporin and some antiretrovirals, cholelithiasis |
Malabsorption syndromes, cholestasis, pregnancy/breastfeeding |
| Lorcaserin (Belviq) | 10 mg twice daily | 5-HT2C agonist | 3.0–3.6 % [50, 51] | Common/mild: headache, nausea, dry mouth, dizziness, fatigue, constipation Rare/severeb: serotonin syndrome, valvular heart disease, cognitive impairment, priapism, hypoglycaemia |
SSRIs/SNRIs and related drugs, coexisting congestive cardiac failure, valvulopathy, pregnancy |
| Phentermine/topiramate (Qsymia) | Starting dose 3.75 mg/23 mg daily, standard maintenance dose 7.5 mg/46 mg daily, highest dose 15 mg/92 mg daily | Norepinephrine + dopamine release/GABA modulation | 6.6 % at standard dose, 8.6–9.3 % at highest dose [58, 59] | Common/mild: paraesthesia, dizziness, altered taste, insomnia, constipation, dry mouth Rare/severeb: teratogenic, tachycardia, acute myopia and secondary angle-closure glaucoma, cognitive impairment, metabolic acidosis, creatinine elevation, hypoglycaemia |
Pregnancy, recent or unstable cardiovascular disease, glaucoma, hyperthyroidism, MAO inhibitors or sympathomimetic amines |
| Bupropion/naltrexone (Contrave, Mysimba) | 16 mg/180 mg twice daily, titrated over 4 weeks | Dopamine + norepinephrine reuptake inhibitor/opioid antagonist | 3.2–5.2 % [64–67] | Common/mild: nausea, constipation, headache, vomiting, dizziness, insomnia, dry mouth, diarrhoea Rare/severeb: suicidal thoughts, seizures, hypertension, hepatotoxicity, angle-closure glaucoma, hypoglycaemia |
Seizure disorder, uncontrolled hypertension, anorexia nervosa, alcohol or opiate withdrawal, bipolar disorder, end-stage renal disease, MAO inhibitors |
| Liraglutide 3 mg (Saxenda) | 3 mg daily by subcutaneous injection, titrated over 5 weeks | GLP-1 receptor agonist | 4.0–6.0 % [70, 71] | Common/mild: nausea, vomiting Rare/severeb: acute pancreatitis, thyroid C cell tumours, gall bladder disease, tachycardia, renal impairment, hypoglycaemia |
Medullary thyroid carcinoma, multiple endocrine neoplasia, gastroparesis, pregnancy |
5-HT serotonin, GABA gamma-aminobutyric acid, GLP-1 glucagon-like peptide-1, MAO monoamine oxidase, SNRI serotonin/norepinephrine reuptake inhibitor, SSRI selective serotonin reuptake inhibitor
aWe have not listed all reported adverse effects
bWe have included adverse events not conclusively proven to be treatment related in the ‘rare/severe’ category