Assessment of prescribed medications and pattern of distribution for potential drug-drug interactions among chronic kidney disease patients attending the Nephrology Clinic of Lagos University Teaching Hospital in Sub-Saharan West Africa.

Introduction: Life expectancy has increased significantly among chronic kidney disease (CKD) patients due to the extensive use of polypharmacy practice for medication prescriptions. This predisposes them to potential drug-drug interactions (DDIs), which can lead to an increase in morbidity, mortality, length of hospital stay, and health care cost.

Methods: This was a 30-month retrospective study that reviewed the medical case records of consenting adult CKD patients from January 2014 to June 2016. The Medscape drug reference database was used to evaluate patients' medications for potential DDIs.

Results: This study involved 123 adult CKD patients (63 [51.22%] males and 60 [48.78%] females) with a mean age of 53.81±16.03 years. The most common comorbid conditions were hypertension (112 [91.10%]) and diabetes mellitus (45 [36.60%]). Regarding the form of nephrological interventions being offered, the majority of the respondents - 66 (53.66%) were on maintenance dialysis, followed by 53 (43.09%) respondents on conservative care, while 4 (3.25%) respondents were on renal transplantation. A total of 1264 prescriptions were made, and the mean number of prescribed medications per patient was 10.28±3.85. The most frequently prescribed medications were furosemide (88 [71.6%]), heparin (67 [54.47%]), lisinopril (65 [52.9%]), oral calcium carbonate (CaCO₃) (63 [51.2%]), α-calcidol (62 [50.4%]), and erythropoietin (61 [49.6%]). A total number of 1851 potential DDIs were observed among 118 patients. The prevalence of potential DDIs in this study was 78.0%, while the mean DDI per prescription was 1.50. Among the potential DDIs observed, the severity was mild in 639 (34.5%) patients, moderate in 1160 (62.7%) patients, and major in 51 (2.8%) patients and only 1 (0.1%) patient was of contraindicated drug combination. The most frequent DDIs' pattern observed was between oral CaCO₃ and oral ferrous sulfate. There was a statistically significant association between the number of prescribed medications and the estimated glomerular filtration rate (eGFR; pre-ESRD and ESRD staging) with a P-value of 0.00000119. This implies that the number of prescribed medications increases as the eGFR declines in advance CKD stage patients.

Conclusion: Most of these interactions have moderate severity and delayed onset, hence the need to follow-up these patients after prescription in order to reduce associated morbidity, mortality, length of hospital stay, and health care cost. Physicians and clinical pharmacists should utilise available interaction software to avoid harmful DDIs in these patients.