Clinical pharmacy services aim to optimise medication use, enhance patient outcomes, and reduce the risk of drug-related harm through patient-centred pharmaceutical care. In hospital settings, clinical pharmacists collaborate with physicians and other healthcare professionals as part of a multidisciplinary team to identify, prevent, and resolve drug-related problems (DRPs). Pharmacist interventions are defined as any action initiated by a pharmacist that directly contributes to patient management or results in a modification of medication therapy. The clinical and economic benefits of such interventions have been widely recognised in various healthcare environments.

This quasi-experimental study aims to investigate the impact of clinical pharmacy services on drug use and the management of DRPs in patients with renal impairment admitted to the general internal medicine ward. The study also evaluates the contribution of the clinical pharmacist to optimising the use of drugs that require renal dose adjustment.

The study was conducted in a university hospital and included three consecutive patient groups: observation (control), education, and intervention. In the observation group, no pharmacist intervention was performed. In the education group, physicians received a structured educational presentation on renal dose adjustment for commonly prescribed medications. In the intervention group, the clinical pharmacist actively participated in daily ward rounds, identified and resolved DRPs, and provided recommendations to physicians. DRPs were classified using the Pharmaceutical Care Network Europe (PCNE) classification version 9.1.

This study evaluates whether the integration of a clinical pharmacist into the healthcare team can improve the quality of pharmacotherapy, reduce DRPs-particularly those associated with renal dysfunction-and enhance patient safety and outcomes in hospitalised patients.

Patients with renal impairment are at high risk for adverse drug reactions, medication errors, and inappropriate prescribing due to altered pharmacokinetics and pharmacodynamics. As renal function declines, dose adjustments and careful monitoring are required for many commonly prescribed drugs. Inappropriate dosing and the use of nephrotoxic agents in this population can lead to drug accumulation, toxicity, or therapeutic failure, thereby increasing the risk of hospitalisations, prolonged stays, and mortality. Previous studies have highlighted that a considerable proportion of drug-related hospital admissions are attributable to inadequate dose adjustment in patients with reduced kidney function. Therefore, careful monitoring and evidence-based dose optimisation are crucial in these patients.

Incorporating clinical pharmacy services into the care of patients with renal impairment may improve medication safety and treatment outcomes. Clinical pharmacists are well-positioned to identify and prevent drug-related problems (DRPs), recommend dose adjustments, and collaborate with physicians to enhance the quality of pharmacotherapy. Pharmacist-led interventions-such as medication reviews, dose optimisation, education of healthcare providers, and direct communication of recommendations-have been shown to reduce medication errors and improve patient outcomes in various clinical settings. Furthermore, integrating clinical pharmacists into multidisciplinary hospital teams has demonstrated positive impacts on treatment effectiveness, patient safety, and overall healthcare costs.

The present study aims to investigate drug use patterns, identify DRPs, and evaluate the impact of clinical pharmacy services on the management of patients with renal impairment admitted to the general internal medicine ward. The study specifically focuses on the pharmacist's role in optimising drug therapy for medications requiring renal dose adjustments. By assessing both the educational and interventional contributions of clinical pharmacists, this study intends to provide evidence supporting the integration of these services into routine hospital practice.

This study adopts a prospective, quasi-experimental design and was conducted in the general internal medicine ward of a university hospital. Three consecutive patient groups were included: the observation (control) group, the education group, and the intervention group. In the observation group, patients were followed without any direct pharmacist intervention. In the education group, physicians received structured training on renal dose adjustment principles and the safe use of frequently prescribed medications in renal dysfunction. In the intervention group, the clinical pharmacist actively participated in daily ward rounds, performed comprehensive medication reviews, and identified DRPs related to inappropriate drug selection, dosage errors, potential drug-drug interactions, and drugs requiring renal adjustment. The clinical pharmacist provided evidence-based recommendations to physicians regarding clinically significant findings, and these interventions were documented systematically.

All identified DRPs were classified according to the Pharmaceutical Care Network Europe (PCNE) classification system version 9.1. The clinical pharmacist's recommendations and physician acceptance rates were also recorded. Patient data-including demographic information, comorbidities, renal function parameters, prescribed medications, and relevant laboratory results-were collected prospectively. Statistical comparisons were made between the three study groups to evaluate the effect of educational and interventional phases on the frequency and nature of DRPs, particularly those associated with renal dysfunction.

Through this design, the study aims to demonstrate the stepwise impact of clinical pharmacy involvement-from passive observation to educational and active interventional roles-on the rational use of medicines in patients with renal impairment. It is expected that increased clinical pharmacist participation will lead to a reduction in DRPs, particularly those related to renal dosing errors, and improve patient outcomes by ensuring safer and more effective medication use. The findings are anticipated to contribute to the development of standardised clinical pharmacy service models and support the integration of pharmacists into multidisciplinary care teams for patients with chronic kidney disease and related comorbidities.

Inclusion Criteria:

• Hospitalised in the General Internal Medicine ward with an estimated glomerular filtration rate (eGFR) below 60 mL/min/1.73 m².
• Hospital stay of at least 48 hours.
• Receiving at least one medication that requires dose adjustment in renal impairment.
• Age 18 years or older.

Exclusion Criteria:

• eGFR value of 60 mL/min/1.73 m² or higher.
• Not receiving any medication that requires renal dose adjustment.
• Hospital stay shorter than 48 hours.
• Age under 18 years.
• Refusal or inability to provide informed consent.
• Lack of sufficient cognitive ability to participate in the study.

The IPD will not be shared due to ethical necessities.