tetrabenazine

Taking tetrabenazine (Xenazine) can make you depressed and cause you to have thoughts of suicide or harming yourself, especially if you have Huntington's disease. Your provider might screen you for depression and suicidal thoughts throughout your treatment. If you or anyone around you notice that you have suicidal thoughts, feelings of depression, or unusual behavior (e.g., anxiety, panic attacks, difficulty sleeping, feeling angry or irritated, restlessness) while taking tetrabenazine (Xenazine), call your provider right away. If your depression or suicidal thoughts don't go away, you might have to stop taking tetrabenazine (Xenazine).

Huntington's disease is a condition that can cause changes in mood, ability to think clearly, chorea, muscle stiffness, and ability to function normally over time. Medications like tetrabenazine (Xenazine) can also worsen these symptoms as well. If you're taking tetrabenazine (Xenazine) and have Huntington's disease, your provider will examine you every so often to make sure this medication is safe and working properly for you. You might need to stop taking tetrabenazine (Xenazine) for a period of time to see if your symptoms are due to your Huntington's disease or the medication. If your chorea has improved, your provider might lower your dose or even have you stop taking tetrabenazine (Xenazine).

Most people respond to doses of up to 50 mg of tetrabenazine (Xenazine) per day. However, if your symptoms aren't controlled with 50 mg per day, you might need to get genetic testing done for a specific enzyme that metabolizes (breaks down) tetrabenazine (Xenazine). The presence and properties of this enzyme affects how fast your body breaks down the medication, which affects the level of tetrabenazine (Xenazine) in your body and how well the medication works. Your dose will be adjusted based on information about the properties of this enzyme from the genetic testing. If this test shows you break down tetrabenazine (Xenazine) quickly, you'll need a dose of up to 100 mg per day to treat your symptoms.

• Risk factors: Taking antipsychotic medications or other medications that lower dopamine levels

Tetrabenazine (Xenazine) can cause a rare, but life-threatening condition called neuroleptic malignant syndrome (NMS). Symptoms include high fever, sweating, stiff muscles, confusion, not being aware of your surroundings, and fast or irregular heartbeat. Your risk is higher if you take other medications that can cause NMS, such as antipsychotics (e.g., haloperidol (Haldol), risperidone (Risperdal), olanzapine (Zyprexa)). If you experience any of these symptoms while taking tetrabenazine (Xenazine), get medical attention as soon as possible. You'll likely have to stop taking tetrabenazine (Xenazine) and be switched to another medication.

Tetrabenazine (Xenazine) can make you feel restless (like you can't sit still), squirmy or fidgety, or agitated. These are signs of a complex movement problem called akathisia.

Tetrabenazine (Xenazine) can also cause parkinsonism, or abnormal movements, such as a tremor, slow movement, impaired speech, muscle stiffness, and losing your balance easily. These abnormal movements can lead to falls. Since muscle stiffness can be a symptom of Hungtington's disease, it's important to tell your provider if you experience this. They can help you figure out if it's from the disease or if it's a side effect of the medication.

If you experience any of these abnormal movements while taking tetrabenazine (Xenazine), tell your provider. Your dose might need to be lowered or you might need to stop the medication.

• Risk factors: Low heart rate | Low potassium and magnesium blood levels | Taking other medications that cause QT prolongation | Born with QT prolongation | History of abnormal heart rhythms (arrhythmias)

Although rare, tetrabenazine (Xenazine) can delay when your heart squeezes (contracts) and then relaxes. This condition is known as QT prolongation and can raise the risk for life-threatening abnormal heart rhythms. Your risk for QT prolongation is higher if you have a low heart rate, low potassium or magnesium blood levels, or take other medications that cause QT prolongation. Make sure to tell your provider about all the medications you're taking, and don't start any new medications or supplements while taking tetrabenazine (Xenazine) without talking to your provider or pharmacist first. People born with QT prolongation or have a history of arrhythmias should avoid taking tetrabenazine (Xenazine). If you feel your chest pounding, short of breath, chest pain, feeling faint, or lightheaded while taking tetrabenazine (Xenazine), call 911 right away, so you can be examined for this heart rhythm problem right away.

Tetrabenazine (Xenazine) can raise your prolactin levels. Prolactin is a hormone made in your brain that causes milk production and breast growth in women, although men also make some prolactin as well. Too much prolactin can cause weak bones, breast growth (for both men and women), and can even play a role in breast cancer. If you experience breast growth, breast milk leakage, or loss of interest in sex while taking tetrabenazine (Xenazine), contact your provider so you can be tested to see if you have a high prolactin level.