Introduction
The prevalence of obesity is increasing rapidly in all age
groups in the United States and in most EU-countries and is
one of the fastest growing epidemics, now affecting 10–40%
of the adult population. Obesity increases the risk of serious
comorbidity such as type 2 diabetes, cardiovascular disease,
certain cancers and reduced life expectancy, and these complications
may account for 5–10% of all health costs in
Western countries [1]. Of course, dietary modifications and
physical activity increase are the first (and the most costeffective)
approach to the treatment of obesity [2]; however,
in many cases, a pharmacological treatment would help
patients to loose weight and to reinforce their motivation
in dietary protocol prosecution [3]. The US Food and Drug
Administration approves for long-termuse of only two antiobesity
drugs: orlistat, a lipase inhibitor that inhibits absorption
of dietary fat by approximately 30%, and sibutramine, a
centrally acting agent which enhances satiety and thermogenesis
by inhibiting serotonin and noradrenaline
re-uptake [4]. Both drugs are able to induce a significant
weight loss compared to life-changes alone, to maintain
the weight loss after 2 years of treatment and to improve
metabolic pattern of both diabetic and hyperlipoproteinaemic
patients [5]. Orlistat has mainly mild to moderate
gastrointestinal side effects that usually attenuate with
the prosecution of the treatment but often not acceptable
from the patients [6] and some pharmacokinetic interactions
that are rare but potentially relevant, with cyclosporin
[7] and warfarin [8]. Sibutramine is also well
tolerated, although it may cause dry mouth, anorexia
and insomnia, while recently some concerns have been
raised about its safety in patients at risk of cardiovascular
disease [9]. However, actually, results from clinical trials
give contrasting results about the sibutramine effect on
heart rate and blood pressure. Although there are studies
in which orlistat and sibutramine demonstrated their
effectiveness on body weight reduction and on some
metabolic parameters, no studies compared orlistat and
sibutramine in the same trial.