Drug interactions in primary healthcare in the George area, South Africa : a cross-sectional study
Thesis (MFamMed)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Aim: To investigate the prevalence of potential drug-drug interactions in primary healthcare clinics in the George subdistrict. Objectives included: To investigate and quantify the following risk factors: patient age, poly-pharmacy, gender, multiple prescribers and recorded diagnoses, as well as to identify and quantify the drugs involved, including the level of any drug-drug interactions. Design: A descriptive cross-sectional study was performed at four primary healthcare clinics in George from 400 randomly selected patients’ files for patients who attended these clinics from 1 February to 30 April 2010. Demographics, recorded diagnoses and all concurrently prescribed drugs were recorded and analysed. The level of drug-drug interaction was classified using the OpeRational Classification of drug-drug interactions designed by Hansten and Horn. Results: The prevalence for moderate interactions was 42%, severe interactions 5.25% and contraindicated combinations was 0.5%. The most common drugs involved in potential drug interactions were: enalapril, aspirin, ibuprofen, furosemide and fluoxetine. The most common drugs involved in potentially severe interactions were: warfarin, aspirin, fluoxetine, tramadol and allopurinol. Two contraindicated combinations were found: verapamil plus simvastatin, and hyoscine butyl bromide with oral potassium chloride. Increasing age and poly-pharmacy were associated with an increased risk for potential drug-drug interactions. Input from the regional hospital specialist departments greatly increased the risk of being prescribed a potential drug-drug interaction. Eighty one per cent (17/21) of severe interactions were from this group. The majority of patients in the sample were female (65.5%) but there was no differences in the percentage of drug interactions between males (43.4%) and females (43.1%). Conclusion: Potential drug-drug interactions are commonly prescribed in primary healthcare clinics in the George subdistrict. Drug interactions are predictable and preventable. It would seem prudent to put into place a method of reducing the risk. Further research is needed to identify effective interventions suitable for resource constrained centres. The risk factors identified in this study may assist in designing such an intervention.
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