General Information

Geodon for injection has been approved by the FDA to rapidly control agitated behavior and psychotic symptoms (such as hallucinations and delusions) in patients with acute exacerbations of schizophrenia. Geodon is the first atypical antipsychotic medication approved in the United States for intramuscular (IM) use.

Geodon blocks the action of serotonin and dopamine, two mood-regulating chemicals found in the brain. An orally administered form of this medication was approved by the FDA for schizophrenia in February 2001. However, with acute agitation (characterized by uncooperative or even violent behavior), immediate intervention is required. Intramuscular delivery provides a rapidly effective option for these emergency situations.

Clinical Results

Intramuscular Geodon was evaluated for effectiveness in two short-term, double-blind trials. These trials included schizophrenic subjects who were considered by the study investigators to be "acutely agitated" and in need of IM antipsychotic medication. The subjects were also required to have a score of three or more on at least three of the following items of the Positive and Negative Syndrome Scale (PANSS): anxiety, tension, hostility and excitement.

Both studies compared a 2 mg control dose to higher doses of Geodon. In the first trial, the higher dose was 20 mg, which could be given up to four times in the 24 hours of the study, with intervals between dosing of no less than four hours. In the second study, the higher dose was 10 mg. This dose could also be given up to four times in 24 hours, but with interdose intervals of no less than two hours.

The first trial (involving 20 mg or 2 mg doses of Geodon) was a one-day, double-blind, randomized study (n=79). Results showed that Geodon 20 mg was statistically superior to the 2 mg dose, as assessed by area under the curve (AUC) of the Behavioral Activity Rating Scale (BARS) at zero to four hours, and by Clinical Global Impression (CGI) severity at four hours and study endpoint. The BARS is a seven point scale with scores ranging from one (difficult or unable to rouse) to seven (violent, requires restraint).

The second trial (involving 10 mg or 2 mg doses of Geodon) -- also a one-day, double-blind, randomized study (n=117) -- showed that Geodon 10 mg was statistically superior to Geodon 2 mg according to the AUC of the BARS at zero to two hours, but not as assessed by CGI severity.

Side Effects

Testing has shown that ziprasidone (the active component of Geodon) has a greater capacity to prolong the QT/QTc interval of an electrocardiogram compared to several other antipsychotic drugs. This effect is important because it is associated with torsade de pointes-type arrhythmia, a potentially fatal polymorphic ventricular tachycardia (rapid heart rate), and sudden death.

In clinical studies, adverse events associated with the use of ziprasidone (incidence of 5% or greater) included somnolence (drowsiness) (14%), extrapyramidal syndrome (5%) and respiratory disorder (8%).

Mechanism of Action

The mechanism of action of ziprasidone, as with other drugs having efficacy in schizophrenia, is unknown. However, it has been proposed that this drug’s efficacy in schizophrenia is mediated through a combination of dopamine type 2 (D2) and serotonin type 2 (5HT2) antagonism. Antagonism at receptors other than dopamine and 5HT2 with similar receptor affinities may explain some of the other therapeutic and side effects of ziprasidone. (from Geodon Prescribing Information)