What is ziprasidone, and how does it work (mechanism of action)?
Ziprasidone is an oral and injectable drug that is used for treating psychoses, for example,
schizophrenia. Although the mechanism of action of ziprasidone is not known, 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 the beneficial effect of ziprasidone is due to its blocking of
dopamine and serotonin receptors. It also inhibits the re-uptake of serotonin and norepinephrine by nerves in the brain like some anti-depressant drugs. Ziprasidone is associated with little or no weight gain, a feature that distinguishes it from other anti-psychotic drugs. Similarly, ziprasidone is unique among anti-psychotic drugs in that it does not increase cholesterol levels. The FDA approved ziprasidone as a treatment for schizophrenia in February 2001.
What brand names are available for ziprasidone?
Is ziprasidone available as a generic drug?
Do I need a prescription for ziprasidone?
What are the side effects of ziprasidone?
Some of the most common side effects associated with ziprasidone are:
- feeling unusually tired (1 in 7 patients),
- nausea (1 in 10),
- constipation (1 in 11),
- dizziness (1 in 12),
- restlessness (1 in 12), diarrhea (1 in 20), and
- rash (1 in 20).
Ziprasidone may cause a a condition consisting of abnormal muscle movements, including tremor, shuffling, and uncontrollable movements (1 in 20 patients).
There is a slight risk (1 in 1500 patients) that ziprasidone by itself could significantly increase the QT interval. There is an even smaller risk (1 in 4000 patients) that it could cause a potentially serious change in the rhythm of the heart.
Ziprasidone frequently causes tiredness (1 in 7 patients). Therefore, care should be exercised in any activity requiring mental alertness, such as operating a motor vehicle (including automobiles) or operating hazardous machinery. Less common side effects include seizures (1 in 250 patients).
As with other antipsychotics, long-term use of ziprasidone may lead to a potentially irreversible condition called tardive dyskinesia (involuntary movements of the jaw, lips, and tongue).
A potentially fatal complex referred to as neuroleptic malignant syndrome (NMS) has been reported with other anti-psychotic drugs. Patients who develop NMS may have high fevers, muscle rigidity, altered mental status, irregular pulse or blood pressure, rapid heart rate, excessive sweating, and heart arrhythmias.
Although there is no clear link between ziprasidone and diabetes, patients should be tested during treatment for elevated blood-sugars. Additionally, persons with risk factors for diabetes, including obesity or a family history of diabetes, should have their fasting levels of blood sugar tested before starting treatment and periodically throughout treatment to detect the onset of diabetes. Any patient developing symptoms that suggest diabetes during treatment should be tested for diabetes.
What is the dosage for ziprasidone?
Ziprasidone usually is taken twice a day. The usual starting dose is 20 mg twice daily. The dose may be increased over time to achieve the desired effect. Ziprasidone should be taken with food (for example, shortly after a meal) since when taken on an empty stomach, much less ziprasidone is absorbed.
Schizophrenia is the most disabling mental illness.
Which drugs or supplements interact with ziprasidone?
Ziprasidone has a modest effect on the electrical activity of the heart which can be seen on the electrocardiogram (EKG) as a prolongation of the QT-interval. (See discussion below.) Other drugs which also affect the QT interval can add to the effects of ziprasidone and lead to serious
disturbances in the rhythm of the heart. Due to the potential for such additive effects on the QT interval, ziprasidone should not be taken with thioridazine (Mellaril), quinidine (Quinidex), moxifloxacin (Avelox), pimozide (Orap), sotalol (Betapace), dofetilide (Tikosyn), and sparfloxacin (Zagam).
Carbamazepine (Tegretol) increases the body’s ability to eliminate ziprasidone and, therefore, may reduce the levels and lessen the effectiveness of ziprasidone. Conversely, ketoconazole (Nizoral) reduces the body’s ability to eliminate ziprasidone and may cause increases in levels of ziprasidone and more side effects. Ketoconazole does this by blocking the enzyme that eliminates ziprasidone, cytochrome P450 3A4. Other drugs that also block this enzyme and may increase the levels of ziprasidone include itraconazole (Sporanox), fluconazole (Diflucan), erythromycin, clarithromycin (Biaxin), nefazodone (Serzone), verapamil (Calan, Isoptin, Verelan), and diltiazem (Cardizem, Tiazac, Dilacor).
Is ziprasidone safe to take if I’m pregnant or breastfeeding?
Ziprasidone has not been studied in
pregnant women, but studies in animals have shown that ziprasidone causes birth defects. Nevertheless, a physician may chose to use ziprasidone if he/she feels that its benefits outweigh this potential concern.
It is not known if ziprasidone is excreted in
breast milk. Since most drugs are excreted in breast milk, it is recommended that women receiving ziprasidone should not breast feed their infants.
What else should I know about ziprasidone?
What preparations of ziprasidone are available?
Ziprasidone is available as capsules of 20 mg (blue/white), 40 mg (blue/blue), 60 mg (white/white) and 80 mg (blue/white). The injectable form is available in vials containing 20 mg of lyophilized ziprasidone that must be reconstituted with 1.2 ml of sterile water before injection.
How should I keep ziprasidone stored?
Capsules should be stored at room temperature, from 15 C to 30 C (59 F
to 86 F).