Context: Sibutramine, or its structurally related analogs, is often found as an adulterant in proprietary herbal slimming products in Hong Kong. A few solitary case reports of sibutramine-associated psychosis have been published since 2000. As the only tertiary referral center for clinical toxicology analysis in Hong Kong, we noticed that psychosis was an unusually common feature in patients taking "herbal slimming products" adulterated with sibutramine or its structurally related analogs over the past 5 years.
Objective: To examine the association between psychosis and the use of sibutramine-adulterated herbal products, in an attempt to elucidate this possible adverse drug reaction.
Methods: This retrospective study reviewed all cases hospitalized with psychotic symptoms confirmed to have used herbal slimming products adulterated with sibutramine, or its analogs, between January 2004 and October 2009. The cases' clinical features, outcome, drug history, and analytical findings of the offending slimming products were studied. Results. Among the 16 confirmed cases, 15 (94%) were female; the median age was 19 years (range: 15-47). Auditory hallucination was documented in 10 (63%), visual hallucination in 6 (38%), persecutory ideas in 6 (38%), delusions in 4 (25%), and suicidal ideation in 2 (13%). For 20 "herbal" slimming products analyzed, 16 were found to have been adulterated with sibutramine, 2 with N-desmethyl-sibutramine, and 1 with N-bisdesmethyl-sibutramine. Other concomitant adulterants were also found and included phenolphthalein in 9, fenfluramine, mazindol, animal thyroid tissue in 2, hydrochlorothiazide and spironolactone in 1. Eight patients disclosed the source of the products: four through the Internet, one obtained over-the-counter locally, with three acquired outside Hong Kong.
Conclusion: Slimming products claimed "herbal" in origin could often be adulterated with sibutramine and other Western medications. We observed an association between the use of these products and psychotic features. Further studies are warranted to study whether these adverse events are an uncommon adverse drug reaction of sibutramine.