Routine Plasma Level Determination to Compare Actual vs Expected Plasma Levels at Psychiatric Inpatient Admission

Context Noncompliance or incomplete compliance with psychopharmacological medication by psychiatric patients is a frequent risk and may be underreported by classical methods (e.g., pill counts or coloring additives). Objective To determined the prevalence of incomplete compliance and/or faster-than average elimination of the medication by comparing actual plasma levels with those expected from the prescribed dosage under naturalistic routine conditions. Design Forty-five day prospective routine survey. Setting University acute inpatient clinic. Participants All consecutive admissions for acute inpatient treatment from June 1, 2005 to July 15, 2005 who had been treated with antidepressants and/or antipsychotics. Intervention Determination of plasma levels of all psychiatric medications and their comparison to the expected plasma levels, based on known preadmission dosing regimen and average pharmacokinetic data. Main outcome measures The percentage of admissions with actual plasma level that were (a) more than 2-fold lower or (b) more than 2-fold higher than the expected plasma level or (c) differing only 0.5- to 2-fold from the expected plasma level.