sibutramine is an orally administered agent for treatment of obesity. chemically, the active ingredient is a racemic mixture of the (+) and (-) enantiomers of cyclobutanemethanamine, 1-(4-chlorophenyl)-n, n-dimethyl-a - (2-methylpropyl)-, hydrochloride, monohydrate, and has an empirical formula of c17h29cl2no. its molecular weight is 334.33. the structural formula is shown below: sibutramine hydrochloride monohydrate is a white cream crystalline powder with a solubility of 2.9 mg/ml in ph 5.2 water. sibutramine is used together with a reduced-calorie diet to help you lose weight and to help keep the lost weight from returning. sibutramine is thought to work by increasing the activity of certain chemicals, called norepinephrine and serotonin, in the brain. usage: follow a reduced-calorie diet while taking sibutramine, as directed by your doctor. sibutramine may be taken with or without food, on a full or empty stomach. however, if your doctor tells you to take it in a certain way, take it as directed. you must follow a reduced-calorie diet while taking sibutramine in order to lose weight and keep the lost weight from returning