The current status of antiobesity drugs

The currently available antiobesity drugs will produce an additional mean weight loss of approximately 0.5 lb (0.23kg) per week for a limited period of time. There is no major difference between the weight losing properties of the various drugs, and choice of drug depends in part on other factors such as cost and side effects. Those drugs affecting catecholaminergic pathways such as phentermine and diethylpropion can be prescribed intermittently because this is as effective, cheaper and presumably less likely to result in dependence than continuing therapy. Fenfluramine however is best given continuously, the dose being built up and reduced stepwise to avoid the dangers of withdrawal depression. Individual response may depend partly upon drug compliance and metabolism but cannot be predicted except by trial and error. Once a drug is discontinued, weight regain is the rule and there is no evidence that drug therapy helps to re-educate faulty eating habits. It follows that therapy can be most easily justified if there is a short term need to achieve weight loss, e.g. prior to elective surgery. In some patients, weight regain may be prevented by giving the drug long term but the complications of long-term administration have yet to be evaluated. If it can be justified at all, it is in those subjects with complicated obesity. The development of a non-pharmacological way of preventing weight regain following drug therapy would enhance the potential usefulness of an antiobesity agent.