A risk-benefit assessment of anti-obesity drugs

This review evaluates the benefits and potential health risks of the curren tly used drugs that are approved for the pharmacological treatment of obesi ty. Analysis of several long term clinical trials indicates that all of the se drugs are efficient in reducing excess bodyweight, and that the majority of them allow the maintenance of the reduced bodyweight for at least I yea r. However, the loss of body weight attributable to these drugs is in gener al rather modest, approaching only 0.2kg per week during the first 6 months of treatment, and at least a partial regain of bodyweight occurs when thes e drugs are used for periods longer than 1 year. All of these drugs induce several adverse effects. Although most of these a dverse effects are mild and transient, the prolonged use of adrenergic or s erotonergic anorectic drugs, or their use as combination treatment, may ind uce serious and potentially life-threatening complications, such as primary pulmonary hypertension or varvular heart disease. The adrenergic appetite- suppressing drugs are not recommended for the treatment of obesity, since t heir safety has never been evaluated in long term clinical trials, and beca use of their stimulatory effects on the cardiovascular and nervous systems. The serotonergic drugs, such as fenfluramine and dexfenfluramine, have bee n the most widely used during the past decade; however, both these compound s have recently been withdrawn from e market, since their use was associate d with serious cardiovascular complications. The safety of the prolonged th erapeutic use of newer compounds such as sibutramine and orlistat has not y et been demonstrated. Therefore, none of the currently available anti-obesi ty medications meets the criteria of an 'ideal antiobesity drug' and, if pr escribed, these medications should be used with caution and only under care ful medical suppression, Since obesity is recognised as a chronic health-threatening condition, and since classical behavioural therapeutic approaches lack long term efficacy, there is clearly a need for an efficient pharmacological treatment offerin g an acceptable safety profile. Such a treatment is not available at presen t. Development of new agents and a more careful assessment of the safety of currently available drugs are needed.