Warnings and precautions
DRUG INTERACTIONS
CNS active drugs: Sibutramine should not be used concomitantly with monoamine oxidase inhibitors (MAOI) and serotonergic drugs (selective serotonin reuptake inhibitors) since rare, but serious, constellation of symptoms termed ‘serotonin syndrome’ have been reported. At least two weeks should elapse between discontinuation of an MAOI and initiation of treatment with sibutramine. Similarly, at least two weeks should elapse between discontinuation of sibutramine and an MAOI.
Drugs that may raise blood pressure and/or heart rate: Concomitant use of sibutramine and other agents that may raise blood pressure or heart rate (e.g. certain decongestants, cough, cold and allergy medications that contain agents such as phenylpropanolamine, ephedrine or pseudoephedrine) have not been evaluated. Caution should be used when prescribing sibutramine to patients who use these medications.
Drugs that inhibit cytochrome P450 (3A4) metabolism: In vitro studies have shown that ketoconazole, erythromycin and cimetidine inhibit the cytochrome P450 (3A4) mediated metabolism of sibutramine but the magnitude of such an interaction appears to be small and not of clinical significance.
Alcohol: The concomitant use of sibutramine and excess alcohol is not recommended.
BLOOD PRESSURE AND PULSE
Sibutramine substantially increases blood pressure in some patients. Hence regular monitoring of blood pressure is required when prescribing sibutramine. For patients who experience a sustained increase in blood pressure or pulse rate while receiving sibutramine, either dose reduction or discontinuation should be considered. Sibutramine should be given with caution to those patients with a history of hypertension and should not be given to patients with uncontrolled or poorly controlled hypertension.
CONCOMITANT CARDIOVASCULAR DISEASE
Treatment with sibutramine has been associated with increases in heart rate and/or blood pressure. Therefore, sibutramine should not be used in patients with a history of coronary artery disease, congestive heart failure, arrhythmias or stroke.
GLAUCOMA
Because sibutramine can cause mydriasis, it should be used with caution in patients with narrow angle glaucoma.
PULMONARY HYPERTENSION
Certain centrally-acting weight loss agents that cause release of serotonin from nerve terminals have been associated with pulmonary hypertension (PPH), a rare but lethal disease. In pre-marketing clinical studies, no cases of PPH have been reported with sibutramine. Because of the low incidence of this disease in the underlying population, however, it is not known whether or not sibutramine may cause this disease.
SEIZURES
During premarketing testing, seizures were reported in <0.1% of sibutramine-treated patients. Sibutramine should be used cautiously in patients with a history of seizures. It should be discontinued in any patient who develops seizures.
GALLSTONES
Weight loss can precipitate or exacerbate gallstone formation.
RENAL/HEPATIC DYSFUNCTION
Patients with severe renal impairment or severe hepatic dysfunction have not been systematically studied; sibutramine should therefore not be used in such patients.
INTERFERENCE WITH COGNITIVE AND MOTOR PERFORMANCE
Although sibutramine did not affect psychomotor or cognitive performance in healthy volunteers, any CNS active drug has the potential to impair judgment, thinking or motor skills.
MISCELLANEOUS
Organic causes of obesity (e.g. untreated hypothyroidism) should be excluded before prescribing sibutramine.
PREGNANCY
There are no adequate and well controlled studies with sibutramine in pregnant women. The use of sibutramine during pregnancy is not recommended Women of child-bearing potential should employ adequate contraception while taking sibutramine. Patients should be advised to notify their physician if they become pregnant or intend to become pregnant during therapy.
NURSING MOTHERS
It is not known whether sibutramine or its metabolites are excreted in human milk. Sibutramine is not recommended for use in nursing mothers. Patients should be advised to notify their physician if they are breast feeding.
PEDIATRIC USE
The safety and efficacy of sibutramine in pediatric patients under 16 years of age have not been established.