Drug treatment and obesity.

(1) The initial treatment of obesity must include an attempt to modify previous eating pattern and may involve group therapy or behavioral modification. Drug treatment is not indicated unless this dietary approach is shown to be ineffective. (2) Since anti-obesity drugs do not help to establish a new and permanent eating habit, they should never be prescribed except as part of an overall management plan. (3) The potential for abuse with amphetamine and phenmetrazine is such that their use cannot be justified as anorectic agents. (4) Phenmetrazine, diethylpropion, mazindol and fenfluramine will all produce an additional mean weight loss of approximately 0.2 kg per week. They are contraindicated if there is a history of drug misuse, drug dependence or psychiatric illness. They should always be prescribed with caution. With the exception of fenfluramine, they are best given intermittently on the grounds of efficacy, safety and cost benefit. (5) The individual response to drug therapy is extremely variable and may reflect differences in drug pharmacokinetics, metabolic adaptation or, less frequently, drug tolerance. (6) Following drug withdrawal, weight regain is the rule. It follows that therapy can most easily be justified if there is a short term need for weight loss, e.g. prior to elective surgery. (7) The safety and efficacy of long term drug therapy has yet to be established. It may prove justifiable in patients most at risk from obesity or from obesity associated disorders such as diabetes and hypertension. However, at present the only established indication for prolonged administration of the currently available drugs is the use of metformin in insulin independent diabetics. (8) The indications for the pharmacological treatment of obesity remain poorly defined. A number of new approaches are being evaluated, and the future may lie in the development of drugs which enhance thermogenesis or primarily act upon the gastrointestinal tract.