Quetiapine

GENERIC NAME: quetiapine

DRUG CLASS AND MECHANISM
Quetiapine is an oral antipsychotic drug used for treating schizophrenia and bipolar disorder. Although the mechanism of action of quetiapine is unknown, like other anti-psychotics, it inhibits communication between nerves of the brain. It does this by blocking receptors on the nerves for several neurotransmitters, the chemicals that nerves use to communicate with each other. It is thought that its beneficial effect is due to blocking of the dopamine type 2 (D2) and serotonin type 2 (5-HT2) receptors.

PRESCRIPTION: Yes

GENERIC AVAILABLE: No

PREPARATIONS: Tablets: 25, 50, 100, 200, 300, and 400 mg

PRESCRIBED FOR
Quetiapine is used alone or in combination with other drugs to treat schizophrenia and bipolar disorder.

DOSING
Quetiapine usually is taken two or three times daily. The dose usually is increased slowly over several days or weeks to achieve the desired effect. Quetiapine can be taken with or without food.

The initial dose for bipolar disorder is 50 mg twice daily (100 mg/d). The dose can be increased by 100 mg/d to a daily dose of 400 mg/d. Most patients respond to 400-800 mg/d. Doses greater than 800 mg/d have not been studied.

The initial dose for schizophrenia is 25 mg twice daily (50 mg/d). The dose can be increased by 25-50 mg two or three times daily. The target dose is 300-400 mg/d in two or three doses. Patients respond to 150-750 mg/d, and doses greater than 800 mg/d have not been evaluated.

DRUG INTERACTIONS
Phenytoin (Dilantin) and thioridazine (Mellaril) markedly decrease the amount of quetiapine that is absorbed from the intestine and thereby reduces its effectiveness. Therefore, patients taking phenytoin or thioridazine may require higher doses of quetiapine.

Quetiapine can cause hypotension (low blood pressure) and therefore increase the blood pressure lowering effects of antihypertensive drugs.

Quetiapine can increase the sedating effects of other drugs that sedate. Such drugs include narcotic pain relievers [for example, oxycodone and acetaminophen (Percocet, Roxicet, Tylox, Endocet)], barbiturates, sedatives such as alprazolam (Xanax) and clonazepam (Klonopin), ethanol, and blood pressure drugs that can cause orthostatic hypotension, such as prazosin (Minipress) and terazosin (Hytrin).

Quetiapine is eliminated from the body by an enzyme in the liver called cytochrome P450 3A. There is a concern that drugs that strongly interfere with the enzyme, for example, ketoconazole (Nizoral), itraconazole (Sporanox), fluconazole (Diflucan), and erythromycin, clarithromycin (Biaxin), nefazodone (Serzone), verapamil (Calan, Isoptin, Verelan), or diltiazem (Cardizem, Tiazac, Dilacor) may cause elevated and toxic levels of quetiapine.

USES
This medication is used for the treatment of certain mental conditions (e.g., schizophrenia, the manic stage of bipolar disorder).

HOW TO USE
This drug is taken by mouth, generally twice or three times daily. Dosage is based on age, mental condition and other diseases, and is slowly increased as tolerated. It may take several weeks to notice the full benefit of this drug. Continue to take it everyday as directed, even if you are feeling better and thinking more clearly. Avoid eating grapefruit or drinking grapefruit juice while being treated with this medication unless our doctor instructs you otherwise. Grapefruit juice can increase the amount of certain medications in your bloodstream. Consult your doctor or pharmacist for more details.

SIDE EFFECTS
Constipation, drowsiness, dizziness, stomach pain or upset, weight gain or dry mouth may occur. If these persist or worsen, notify your doctor. To relieve dry mouth and protect teeth and gums, you may suck on sugarless candy or use a saliva substitute or ice chips. Report promptly: fainting, unusually fast or irregular heartbeat. Unlikely but report promptly: skin rash, itching, trouble breathing. Very unlikely but report promptly: fever, persistent sore throat, muscle stiffness, confusion, sweating, uncontrolled muscle movements (e.g., tongue or facial muscles), one-sided muscle weakness, cold sensitivity, trouble urinating, black stools, unusual moods. This drug may infrequently make your blood sugar level rise, therefore causing or worsening diabetes. This high blood sugar can rarely cause serious (sometimes fatal) conditions such as diabetic coma. Tell your doctor immediately if you develop symptoms of high blood sugar, such as unusual increased thirst and urination, or vision changes. If you already have diabetes, be sure to check your blood sugar level regularly. This drug may also cause significant weight gain and a rise in your blood cholesterol (or triglyceride) levels. These effects, along with diabetes, may increase your risk for developing heart disease. Discuss the risks and benefits of treatment with your doctor. (See also Notes section.) If you notice other effects not listed above, contact your doctor or pharmacist.

OVERDOSE
If overdose is suspected, contact your local poison control center or emergency room immediately. US residents can call the US national poison hotline at 1-800-222-1222. Canadian residents should call their local poison control center directly. Symptoms of overdose may include drowsiness, rapid pulse, weakness, fatigue, and dizziness.

MISSED DOSE
If you miss a dose, use it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not "double-up" the dose to catch up.

PRECAUTIONS
Before taking quetiapine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. Tell your doctor your medical history, especially of: liver problems, blood vessel disease, very low blood pressure, seizure disorders. (See also Side Effects section.) Also tell your doctor or pharmacist if either you or a family member has a history of the following: diabetes, heart disease, high blood cholesterol/triglyceride levels, high blood pressure, obesity. To avoid dizziness and lightheadedness when rising from a seated or lying position, get up slowly. This is more likely to occur in the first few days after starting or restarting the drug, or after dosage increases. This drug may make you dizzy or drowsy; use caution engaging in activities requiring alertness such as driving or using machinery. Avoid alcoholic beverages. This drug might hinder body temperature control. It is advised not to exercise strenuously, and to avoid extreme heat while using this medication. Caution is advised when using this drug in the elderly because they may be more sensitive to its effects. This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor. It is not known whether this drug is excreted into breast milk. Because of the potential risk to the infant, breast-feeding while using this drug is not recommended. Consult your doctor before breast-feeding.

STORAGE
Store at room temperature between 68 and 77 degrees F (20-25 degrees C) away from light and moisture.

Note : This product information is intended only for residents of the India. Taj Pharmaceuticals Limited, medicines help to treat and prevent a range of conditions—from the most common to the most challenging—for people around the world.