Ziprasidone dosage

A 22-year-old African-American with chronic undifferentiated schizophrenia developed priapism after taking risperidone 4 mg bd, clonazepam 0.5 mg bd, vitamin E 400 IU bd, and a multivitamin for over 6 months. He did not respond to subcutaneous terbuta-line 0.25 mg. Irrigation of the corpora with phenylephrine 200 p resulted in detumescence risperidone was withdrawn. A few months later he took ziprasidone 20 mg bd for 1 week, clonazepam 1 mg bd, and vitamin E 400 IU bd. The ziprasidone dosage was increased to 40 mg bd, but early the next morning he developed a firm erection with some discomfort that lasted about 2 hour and resolved when he urinated the next morning he had a similar erection that also lasted 2 hour and resolved. 

Most antipsychotics have half-fives of elimination in the range of 20 to 40 hours. After dosage stabilization, most antipsychotics (except quetiapine and ziprasidone) can be dosed once daily. It may be possible to dose SGAs less often than their plasma kinetics would suggest. 

Initial treatment Administer ziprasidone capsules at an initial daily dose of 20 mg twice/day with food. In some patients, daily dosage subsequently may be adjusted up to 80 mg twice/day. Dosage adjustments generally should occur at intervals of not less than 2 days. Observe patients for improvement for several weeks before upward dosage adjustment. No additional benefit was demonstrated for doses greater than 20 mg twice/day. 

Ziprasidone is approved for the treatment of schizophrenia and acute mania. For patients with schizophrenia, ziprasidone is usually started at a dosage of 20-40 mg twice a day. In medically healthy, nonelderly patients, the dose can be rapidly titrated over 2-A days to a typical therapeutic dosage of 60-80 mg twice a day. For patients with acute mania, treatment should be initiated at 40 mg twice... 

Ziprasidone s pharmacokinetics permit rapid and predictable dose adjustment, with metabolites that are considered to be clinically inactive ( 134). The results of PET pharmacokinetic and pharmacodynamic studies indicate that a twice daily dosage regimen is appropriate. 

In four other cases the symptoms occurred within 7 days of the start of ziprasidone therapy and improved substantially when the drug dosage was lowered or the drug was withdrawn (25). 

In 70 patients with schizophrenia and persistent symptoms or troublesome adverse effects who were assigned to a flexible dosage (40-160 mg/day) in a 12-month open trial of ziprasidone looking for cognitive improvement, there were significant improvements in executive functions, attention, and information processing domains, but the effect sizes were moderate [138 j. 

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