Mapping Therapeutic Drug Monitoring Research in Low- and Middle-Income Countries: A Scoping Review (2015–2024)

Background: Therapeutic drug monitoring (TDM) helps optimize pharmacotherapy, but research activity in low- and middle-income countries (LMICs) is poorly characterized. This scoping review systematically maps the volume, characteristics, and geographic distribution of TDM research in LMICs from 2015 to 2024. Methods: PubMed, Embase, and Web of Science were searched to identify peer-reviewed TDM studies conducted in World Bank-defined LMICs. Extracted data covered publication characteristics, study design, geographic distribution, drug classes, analytical methods, and descriptive quality indicators. Results: A total of 385 publications from 38 LMICs were included; annual output steadily increased from 29 publications in 2015 to 53 in 2024. The Western Pacific Region accounted for 54.5% of all publications, with China contributing 197 (51.2%). Antimicrobials, immunosuppressants, antiseizure drugs, and antipsychotics accounted for 95.5% of drug-class attributions. Vancomycin (n = 84) and tacrolimus (n = 81) were the most studied drugs. Immunoassay was the predominant analytical method (35.1%), followed by liquid chromatography–mass spectrometry (18.7%). Pharmacy and clinical pharmacology departments were involved in 47.0% of studies. Only 6 low-income countries contributed publications (n = 7) through collaborations with high-income countries (10.4%). The analytical method did not align with the country's income. Pharmacogenetic studies (n = 45), guidelines (n = 2), and external quality assessment studies (n = 2) were rare. Conclusions: TDM research in LMICs has expanded substantially but remains geographically concentrated and focused on drugs with commercial assays. Key gaps remain in pharmacogenetics, implementation science, and guideline development. Strengthening laboratory infrastructure, equitable international collaboration, and locally adapted TDM strategies may help advance precision medicine in resource-limited settings.