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Background and Importance Outpatient parenteral antimicrobial therapy (OPAT) is expanding, yet pharmacokinetic variability and complex dosing may compromise target attainment and remain poorly characterised in this setting.Aim and Objectives Aim: to evaluate a pharmacist-led therapeutic drug monitoring (TDM) workflow in OPAT. Objectives: (i) describe feasibility and dosing strategies, including continuous infusion; (ii) characterise first-sample concentrations by agent; (iii) quantify TDM frequency per patient; and (iv) report clinical and microbiological outcomes and adverse events (AEs).Material and Methods Single-centre prospective pharmacokinetic pilot. All consecutive OPAT patients for whom clinicians requested TDM were included. Dosing used intermittent or continuous infusion as indicated. Courses were prescribed by infectious diseases physicians with initial renal function–adjusted doses. After case review, a clinical pharmacist issued dosing recommendations that the responsible physician implemented. Clinical and microbiological outcomes and AEs were prospectively recorded.Results Thirty-one patients were monitored: median age 66 years (IQR 55–83), Charlson 4 (IQR 2–7), baseline creatinine 0.92 mg/dL (IQR 0.77–1.81) and eGFR 71 mL/min (IQR 37–99). Indications: complicated UTI 29.0%, respiratory 19.4%, skin/soft-tissue 16.1%, osteo-articular 12.9%, renal cysts 9.7%, Campylobacter enteritis 6.5%, pancreatic abscess 3.2%, and candidemia 3.2%; bacteraemia 12.9%. Agents monitored: ertapenem 29.0%, piperacillin 19.4%, ceftazidime 16.1%, cefepime 6.5%, ceftolozane 6.5%, linezolid 6.5%, meropenem 3.2%, vancomycin 3.2%, amikacin 3.2%, anidulafungin 3.2%, aztreonam 3.2%. Continuous infusion was used in 51.9% of evaluable courses (14/27). TDM frequency: 7 patients had two measurements, 4 had three, and 2 had four. Clinical cure occurred in 87.1% (27/31). Among 25 with follow-up cultures, microbiological eradication was 72.0%. Treatment cessation was most often planned end of therapy 74.2%; other reasons: sequencing 9.7%, surgery 6.5%, resistant microorganism 3.2%, neurotoxicity 3.2%, and ertapenem resistance 3.2%. AEs included three neurologic events and one leukopenia. First-sample concentrations showed wide dispersion; drug-specific medians (p25–p75, mg/L): ertapenem 6.6 (3.7–17.7), piperacillin 59.15 (22.1–59.4), cefepime 64.8 (29.9–99.7), ceftazidime 59.4 (32.6–73.2); single values: ceftolozane 53.4, aztreonam 36.5, meropenem 29.3, vancomycin 10.1, amikacin trough 2.04, anidulafungin 7.6.Conclusion and Relevance A pharmacist-led TDM workflow in OPAT was feasible and safe, supported dose optimisation, and achieved high clinical cure with low toxicity. The marked interpatient variability observed at first sampling supports routine TDM, particularly with continuous infusions and in patients with renal impairment.Conflict of Interest No conflict of interest