CPT: 80342
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  • Risperdal®
  • Risperdal® Consta®

Expected Turnaround Time

3 - 5 days

Related Documents

Specimen Requirements




3 mL

Minimum Volume

1.1 mL


Red-top tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant.


Collect specimen just prior to the next dose (trough level).

Storage Instructions

Maintain specimen at room temperature.

Stability Requirements



Room temperature

14 days


14 days


14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Gel-barrier tube

Test Details


Monitor drug levels for optimal therapy


This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.


Liquid chromatography/tandem mass spectrometry (LC/MS-MS)

Reference Interval

20−60 ng/mL

Additional Information

Risperidone is an antipsychotic agent belonging to the benzisoxazole derivatives class. The mechanism of action is unknown; however, antipsychotic activity may be mediated through a combination of dopamine (D2) and serotonic (5HT2) antagonism. Risperidone is well absorbed by the gut. It is extensively metabolized in the liver to a major active metabolite, 9-hydroxyrisperidone, which appears approximately equieffective with risperidone with respect to receptor binding activity. Consequently, the clinical effect of the drug likely results from the combined concentrations of risperidone and 9-OH-risperidone. The pharmacokinetics for the sum of the two, after single and multiple doses, were similar in both rapid and slow metabolizers, with an overall mean elimination half-life of about 20 hours. Steady-state concentrations are reached in five to six days. The plasma protein binding of risperidone and 9-OH-risperidone is about 90% and 77%, respectively. It has been reported that dosing with long-acting risperidone every two weeks produced lower peak levels than oral dosing, while trough concentrations did not differ between the two routes of administration.1 Chronic administration of carbamazepine with risperidone may increase the clearance of risperidone; whereas, chronic administration of clozapine with risperidone may decrease the clearance of risperidone. The primary side effects noted with risperidone are the extrapyramidal symptoms, such as spasmodic, intermittent contraction of facial, neck, or back muscles, but the incidence of these side effects is lower compared with other neuroleptic agents.


1. Eerdekens M, Van Hove I, Remmerie B, et al. Pharmacokinetics and tolerability of long-acting risperidone in schizophrenia. Schizophr Res. 2004 Sep 1; 70(1):91-100. 15246468


Castberg I, Spigset O. Serum concentrations of risperidone and 9-hydroxyrisperidone after administration of the long-acting injectable form of risperidone evidence from a routine therapeutic drug monitoring service. Ther Drug Monit. 2005 Feb; 27(1):103-106. 15665755
Raedler TJ, Schreiner A, Naber D, Wiedemann K. Risperidone in the treatment of acute schizophrenia. J Clin Psychopharmacol. 2004 Jun; 24(3):335-338. 15118488


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
716563 Risperidone (Risperdal(R)), S 716564 Risperidone, Serum ng/mL 9393-0
716563 Risperidone (Risperdal(R)), S 716565 9-OH-Risperidone, Serum ng/mL 9383-1
716563 Risperidone (Risperdal(R)), S 716566 Total (Risp+9-OH) ng/mL 9394-8

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