Assays of drug levels in blood and of other biochemical characteristics
of psychiatric patients are being proposed for clinical application,
although their utility in practice remains uncertain. Exceptions are the
assay of blood levels of anticonvulsants and of lithium ion. Assays of
antidepressant drugs may be especially helpful in the evaluation of
unexpected responses or in the avoidance of unwanted toxic effects and
promise to permit more efficient predictions of individual requirements.
Assays of platelet MAO activity or urinary MHPG excretion remain clinically
less useful. Attempts to correlate blood levels of antipsychotic agents
with clinical effects have been disappointing, although newer assay methods
may prove more useful.