Potential drug-drug interactions among patients with chronic kidney disease admitted at National Hospital: a retrospective study in Tanzania

Abstract

Background: Drug related problems such as drug-drug interactions (DDI) are likely to occur in chronic kidney disease (CKD) patients due to polypharmacy practice. The DDI increases the risk of morbidity, mortality, prolonged hospital and cost of treatment. In most cases, the potential drug-drug interactions (pDDI) are not checked during prescribing or dispensing of polypharmacy for CKD patients in developing countries like Tanzania. Therefore, we documented the pattern and potential drug-drug interactions (DDIs) among CKD patients admitted at Muhimbili National Hospital (MNH).Methods: The study retrospectively reviewed 198 files for CKD patients admitted at MNH between January 2017 and December 2018. The social-demographic characteristics and comorbidities were documented using a checklist. Prescriptions with polypharmacy were reviewed and prescribed medicines were documented. Medscape drug interaction checker was used for pDDIs. The SPSS version 23.0 was used to carry out statistical analysis. Results: The study involved a total of 306 prescriptions with polypharmacy with a mean(±SD) of 6.21(±1.22) medicines per prescription. Majority of patients (77.2%) were in stage 5 of chronic kidney disease. Frequently prescribed medicines were pantoprazole 135(44.1%), furosemide 133(43.5%), ferrotone 101(33.0%), calcium carbonate 91(29.7%), amlodipine 121(39.5%), nifedipine 83(27.1%), bisoprolol 46(15.0%) and clonidine 38(12.4). The prevalence of pDDIs was 94.1%. The total of 1743 potential drug-drug interactions was observed with a mean of 6.03(±2.12) interactions per prescription. Majority of the pDDIs were moderate (67.5%) whereas, 29.5%, 2.6% and 0.3 were minor, serious and contraindicated respectively. The occurrence of pDDIs was associated with stroke (P-value=0.038), diabetes mellitus (p-value=0.049) and hypertension with diabetes mellitus (p-value=0.047).Conclusion: The prevalence of pDDIs was high among the CKD patients. The determinants of pDDIs among CKD patients were hypertension, diabetes mellitus and stroke. Interaction checkers should be incorporated in health system to guide the prescribing and dispensing of medicine for CKD patients.