Ethylene glycol and diethylene glycol impurities determination and assay tests for selected pharmaceutical syrups collected from Addis Ababa, Ethiopia

Diethylene glycol (DEG) and ethylene glycol (EG) impurities and contaminations in pharmaceuticals, particularly in syrups is of particular concern. Many deaths had been recorded in dozens of countries around the globe as recently as 2025. Hence, analytical works are necessary to avoid the risk of contamination of prone pharmaceutical preparations by these impurities. Thus, our work is aimed at surveying the presence of diethylene glycol (DEG) and ethylene glycol (EG) impurities in pharmaceutical syrups obtained from drug retail outlets in Addis Ababa, Ethiopia. Assay of the Active Pharmaceutical ingredient (API) contents was also performed. A total of 56 syrup samples (14 paracetamol, 12 multivitamin, 15 anti-anemic, and 15 anti-allergic cough preparations) were collected from 23 facilities using a purposive sampling strategy in April-2024. The samples were visually inspected. The presence of DEG and EG in the samples were first analyzed using semi-quantitative thin layer chromatography. Then, samples that yielded suspicious results for contaminations with DEG and EG were subjected to confirmatory analysis by gas chromatography (GC). Assay of the API was conducted using high performance liquid chromatography (HPLC). All passed visual inspection as per WHO labeling standards. Thin layer chromatographic test revealed the presence of propylene glycol, in all samples and either diethylene glycol or ethylene glycol in one of the dextromethorphan syrups. GC analysis indicated the presence of ethylene glycol at a concentration of 0.0092%.15.4% of paracetamol and 10% of dextromethorphan syrup samples failed to meet pharmacopeial standards with respect to assay values. Although EG level is below 0.1% thresh hold, substandard paracetamol and dextromethorphan syrups were detected in this investigation. Thus, the results pin points the need for an immediate strict regulatory measure to protect public health.