Clinical Pharmacist Involved in the Treatment of Pneumocystis carinii Pneumonia: A Case Report.

Objective: The first-line treatment for severe Pneumocystis carinii pneumonia (PCP) is trimethoprim-sulfamethoxazole (TMP/SMZ). Here, we report a case involving 6-month-old child with a PCP infection, highlighting the role of clinical pharmacists in providing individualized pharmaceutical care and guidance through the process of therapeutic drug monitoring (TDM).

Methods: The clinical pharmacist monitored the concentration of TMP/SMZ in the serum, urine and sputum of a 6-month-old child with PCP infection. To improve the serum levels of TMP/SMZ, the dose of TMP/SMZ was increased, while infusions of other medications were reduced to decrease the rate of drug excretion. Additionally, the patient received other supportive medications to enhance clinical therapeutic efficacy.

Results: Clinical pharmacists observed that, despite administration of a sufficient dose of TMP/SMZ, plasma concentration of TMP/SMZ remained below the therapeutic window, while urine concentrations were extremely high. This phenomenon was attributed to Augmented Renal Clearance (ARC), often seen in critically ill patients and associated with increased renal clearance. Throughout treatment, the concentrations of SMZ remained below the minimum effective concentration, while the concentrations of TMP fell within the effective target range. However, sufficient therapeutic effects were ultimately achieved and observed in the patient, likely due to improved drug distribution in lung tissue (sputum) and the patient's recovering immune functions. Finally, thanks to individualized pharmaceutical care from clinical pharmacists and the combined efforts of clinicians, the patient was discharged after 58 days of hospitalization.

Conclusion: Throughout treatment, the clinical pharmacist played a vital role in optimizing the treatment plan based on the serum, urine and sputum concentrations of TMP/SMZ and providing pharmaceutical care to ensure a safe, rational and effective medications in children. Individualized dose adjustments, particularly high-dose TMP/SMZ guided by TDM, can significantly enhance the management of PCP in pediatric patients and support clinical pharmacists in delivering individualized pharmaceutical care.