For anyone who has watched a loved one cycle through psychiatric medications for months—or years—before finding an effective regimen, the promise of personalizing treatment from the start is profound. Two converging technologies are now close enough to routine clinical use that their integration could meaningfully shorten that trial-and-error timeline and reduce the harm caused by poorly tolerated psychotropic drugs.
This review in Current Opinion in Psychiatry synthesizes recent evidence on combining therapeutic drug monitoring (TDM)—which measures actual drug concentrations in blood—with pharmacogenomic testing (PGx), which identifies genetic variants in drug-metabolizing enzymes such as CYP2D6 and CYP2C19. Used separately, each tool addresses a different layer of variability: TDM captures real-time pharmacokinetic deviations caused by diet, drug interactions, or organ function, while PGx predicts constitutional metabolizer status. Together, they account for a far larger share of the interindividual variance in drug response that makes psychiatric pharmacotherapy notoriously unpredictable. Recent data cited in the review show TDM reduces relapse rates and hospitalizations in patients on psychotropics, while PGx-guided prescribing has demonstrated measurable gains in remission rates among patients with depression. Notably, the review flags phenoconversion—where drugs or illness states temporarily shift an individual's functional metabolizer phenotype away from their genetic prediction—as a complication that neither tool alone can fully capture.
This synthesis arrives at a clinically important inflection point. Multiple meta-analyses over the past decade have established PGx's benefit in depression, but uptake has been slowed by cost, clinician unfamiliarity, and questions about which patients benefit most. TDM, by contrast, is already standard for lithium and clozapine but underused for many other psychotropics. The review's emphasis on wearable and point-of-care TDM devices is particularly significant: if drug-level monitoring becomes continuous and minimally invasive, the barrier to routine implementation drops substantially. Long-read sequencing for more accurate genotyping addresses a real weakness in current PGx panels, which often miss structural variants. The key limitation here is that much supporting evidence remains observational, and head-to-head trials comparing integrated TDM-PGx protocols against standard care at scale are still sparse. This is a confirmatory and synthesizing contribution rather than a paradigm-shifting one, but its clinical translation implications for adult mental health care are concrete and near-term.