Detailed Drug Information:

DRUG CLASS AND MECHANISM: Sibutramine is a medication that assists with weight-loss by altering neurotransmitters within the brain. Neurotransmitters are chemicals that are produced and released by nerves in order to communicate with other nerves. Released neurotransmitters may attach to other nerves or they may be taken up again by the nerves that release them, a process termed reuptake. Sibutramine blocks the reuptake of the neurotransmitters dopamine, norepinephrine, and serotonin. Blocking the reuptake of neurotransmitters alters the balance of neurotransmitters within the nerve cells and thereby affect nerve function and interaction.

Patients taking sibutramine may achieve a 5-10% reduction from their baseline weight. Additionally, sibutramine-assisted weight loss has been accompanied by improvement in blood lipids (e.g, cholesterol). Sibutramine was approved by the FDA in 1997.

PREPARATIONS: Capsules: 5mg (blue and yellow); 10mg (blue and white); 15mg (white and yellow)

STORAGE: Capsules should be stored at 25°C (77°F). Brief periods at higher or lower temperatures, i.e., 15-30°C (59-86°F) are permitted. The medication should be stored in a tight, light-resistant container. The capsules should be protected from heat and moisture.

PRESCRIBED FOR: Sibutramine is used for weight loss in conjunction with a low calorie diet. Specific populations for whom the medication is recommended are those with an initial body mass index of more than 30 kg/m2 (27 mg/m2 if they also have other risk factors such as diabetes mellitus, high cholesterol or hypertension).

DOSING: Sibutramine is taken once daily, generally in the morning. Therapy usually is started with one 10mg tablet per day. The dose may be increased to 15mg by the physician after several weeks to achieve the desired effect. Doses of up to 60mg have been studied. Sibutramine may be taken with or without food.

DRUG INTERACTIONS: Sibutramine must be converted in the liver to its active form. This conversion is inhibited by ketoconazole (Nizoral), cimetidine (Tagamet) and erythromycin (Erytab, Eryc, Ilosone), and use of these drugs can result in decreased conversion and effectiveness of sibutramine. Several other drugs may have a similar effect. These other drugs include clarithromycin (Biaxin), danazol (Danocrine), diltiazem (Cardizem, Tiazac, Dilacor), fluconazole (Diflucan), fluoxetine (Prozac), itraconazole (Sporanox), propoxyphene (Darvon), troleandomycin(Tao) and verapamil (Verelan, Covera, Calan, Isoptin).

In patients receiving one of the drugs from a class of drugs known as selective serotonin reuptake inhibitors (SSRIs)--e.g., fluoxetine(Prozac), fluvoxamine (Luvox), paroxetine (Paxil), sertraline (Zoloft)--at the same time as monoamine oxidase inhibitordrugs (MAO inhibitors), there have been reports of serious reactions (serotonin syndrome). The serotonin syndrome may include one or more of the following: agitation, anxiety, dizziness, confusion, excessive sweating, disorientation, painful joints, vomiting, hyperexcitement, fever, loss of coordination, loss of consciousness, shivering, fast heart rate, tremor, and weakness. As discussed previously, sibutramine, like the SSRIs, blocks the reuptake of serotonin and may also cause the serotonin syndrome. Therefore, sibutramine should not be used with MAO inhibitors, and there should be at least a 2-week interval between stopping an MAO inhibitor and starting sibutramine. Similarly, there should be at least a 2-week interval after stopping sibutramine and starting an MAO inhibitor. Serotonin syndrome also has been reported with the use of SSRIs at the same time as medications used for migraines such as sumatriptan (Imitrex), zolmitriptan (Zomig) and dihydroergotamine (DHE), as well as dextromethorphan (found in many cough medications such asRobitussin-DM), meperidine (Demerol), pentazocine (Talwin) and fentanyl (Duragesic), or lithium (Eskalith). Therefore, these drugs should not be used with sibutramine.

PREGNANCY: No adequate studies with sibutramine have been done in pregnant women. The use of sibutramine during pregnancy, therefore, is not recommended. Women who could become pregnant should use adequate contraception while taking sibutramine.

NURSING MOTHERS: It is unknown whether sibutramine or its active products accumulate in breast milk. Sibutramine, therefore, is not recommended for nursing mothers.

SIDE EFFECTS: In general, sibutramine is well-tolerated. The most common side effects have been constipation, inability to sleep, headache, and dry mouth. Other side effects include abdominal pain, acne, rash, chest pain, anxiety, joint pain, back pain, excitation, depression, sweating, dizziness, drowsiness, changes in taste, irregular or painful menstrual periods, flu-like syndrome, increased cough, muscle pain, nausea, vomiting, neck pain, nervousness, palpitations, tingling of the extremities, sore throat, and sinus congestion.

Abnormal liver tests have been reported in 1 in 60 persons who receive sibutramine.