14
Treatment
Antipsychotic medications: available oral and short-acting
intramuscular formulations*
Genric name
Trade name
(most common in
U.S., may change)
Metabolic enzymes/
transporters
Available U.S.
formulations
(mg, unless otherwise
noted)
Paliperidone
Invega
P-glycoprotein/ABCB1,
CYP2D6 (Minor), CYP3A4
(Minor) substrate
Tablet, extended release:
1.5, 3, 6, 9
Quetiapine
Seroquel
CYP3A4 (Major), CYP2D6
(Minor) substrate
Tablet, immediate release:
25, 50, 100, 200, 300, 400
Tablet, extended release:
50, 150, 200, 300, 400
Risperidone
Risperdal
CYP2D6 (Major), CYP3A4
(Minor), P-glycoprotein/
ABCB1 substrate,
N-dealkylation (minor),
CYP2D6 weak inhibitor
Tablet: 0.25, 0.5, 1, 2, 3, 4
Tablet, disintegrating:
0.25, 0.5, 1, 2, 3, 4
Oral solution: 1/mL (30 mL)
Ziprasidone
Geodon
CYP1A2 (Minor), CYP3A4
(Minor) substrate,
glutathione, aldehyde
oxidase
Capsule: 20, 40, 60, 80
Solution reconstituted,
IM: 20
* This table includes information compiled from multiple sources. Detailed information on such
issues as dose regimen, dose adjustments, medication administration procedures, handling
precautions, and storage can be found in product labeling. It is recommended that readers
consult product labeling information for authoritative information on these medications.
a
Usually given in divided doses.
b
Up to 9 mg/day has been studied in clinical trials.
c
Clozapine levels should be drawn after at least 3 days on a stable dose and about 12 hours
after the last dose. Levels associated with efficacy show individual variation, but efficacy
typically begins at a level above 250 ng/mL, with the most efficacy seen at levels higher
than 350 ng/mL. U.S. prescribers must complete Clozapine REMS education (https://www.
clozapinerems.com/) and follow requirements for a baseline CBC and ANC, and for ANC
monitoring before and during treatment. Refer to clozapine labeling for detailed instructions
on dose titration and dose adjustments with CYP450 interactions.
d
May be taken without regard to food or other medications unless specifically noted.
e
Olanzapine has been used at higher dosages, typically up to 30 mg/day, although some case
series describe use of up to 60 mg/day.
f
Dosages of risperidone up to 16 mg/day have been studied in clinical trials. However, doses
>6 mg for twice-daily dosing do not appear to confer additional benefit and have a higher
incidence of extrapyramidal symptoms than do lower doses.
(cont'd)
