Orlistat — A Novel Weight Loss Therapy

Abstract

OBJECTIVE: To review the pharmacology, pharmacokinetics, clinical safety and efficacy, drug interactions, and therapeutic issues related to the use of orlistat for treatment of obesity. DATA SOURCES: English-language articles were identified from MEDLINE (1966–July 2000), Roche Laboratories, organizational guidelines, National Institutes of Health and Food and Drug Administration Web sites, and Doctor's Guide online. Key words included obesity, orlistat, and lipase inhibitors. References were also identified from reference sections of published articles. STUDY SELECTION AND DATA EXTRACTION: Prospective, randomized, double-blind, placebo-controlled, human trials were selected for review and discussion. DATA SYNTHESIS: Orlistat is the first agent in the lipase inhibitor class of antiobesity drugs. Orlistat is minimally absorbed and has been shown to reduce body weight by inhibiting absorption (by ∼30%) of ingested dietary fat. Safety and efficacy have been established in one- and two-year double-blind, placebo-controlled trials; adverse effects were primarily, and almost exclusively, gastrointestinal. Due to its ability to block fat absorption, orlistat also has the capability to inhibit absorption of fat-soluble vitamins. Therefore, a daily multiple vitamin is recommended while taking orlistat. CONCLUSIONS: By inhibiting fat absorption, orlistat offers a new treatment modality for weight loss and maintenance. Preliminary data from clinical trials suggest that orlistat may be beneficial in patients with comorbid conditions related to obesity, such as diabetes and hyperlipidemia. However, further studies during postmarketing surveillance are needed to fully establish orlistat's long-term benefits and safety. Orlistat should be considered a useful adjunctive therapy for weight loss and maintenance in obese patients (i.e., body mass index ≥30 kg/m2 or ≥27 kg/m2 if other risk factors are present) committed to lifestyle changes including diet, exercise, and behavioral modification.