Evaluation of heavy metal impurities in metformin tablet brands marketed in Ilorin, Nigeria
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Date
2022-01-31
Journal Title
Journal ISSN
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Publisher
Faculty of Pharmaceutical Sciences, University of Ilorin
Abstract
The safety and quality of pharmaceutical products are important considerations for optimal therapeutic
outcomes. Periodic assessment of heavy metals impurities in pharmaceutical products used for long term treatment of chronic diseases is important to safeguard the health and well-being of patients. This
study investigated the levels of manganese (Mn), copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb)
in brands of metformin tablets commonly prescribed in Ilorin, Nigeria, for the management of
diabetes. Five brands of commonly prescribed metformin tablets were randomly purchased from
pharmacies in Ilorin, North-central Nigeria. Metal concentrations in the acid digested samples were
profiled using Atomic Absorption Spectrophotometry (AAS) method. Method validation results
showed excellent linearity (r
2=0.9921(Mn), 0.9995 (Cu), 0.9998 (Zn), 0.9996(Cd), 0.9913(Pb)), with
limits of detection (0.001, 0.001, 0.002, 0.002 and 0.025 mg/L for Mn, Cu, Zn, Cd and Pb respectively)
and limits of quantification (0.003, 0.003, 0.006, 0.006 and 0.076 mg/L for Mn, Cu, Zn, Cd and Pb
respectively) in the concentration ranges of 2– 10, 0.2–1.6, 0.2–1.6, 1–4 and 1–4 mg/L for Mn, Cu,
Zn, Cd and Pb respectively. Mn, Cu, and Zn were detectable in varying concentrations in all the five
brands of metformin evaluated in this study while none of the brands contained Cd and Pb at detectable
levels. The levels of Mn, Cu and Zn ranged between 0.031-0.062, 0.085-0.112 and 0.040-0.130 mg/mL
respectively across the brands. The highest concentrations of Mn, Cu and Zn were 0.062(0.001),
0.112(0.001) and 0.130(0.001) mg/L respectively. Similarly, maximum daily ingestible amounts for
Mn, Cu and Zn ranges between 0.84-1.75, 2.17-3.03 and 6.12-20.7 μg/day respectively, which were
below permissible daily exposure (PDE). These results indicate that all the metformin brands
evaluated could be safely administered orally to the patients without fear of any of the metal’s toxicity
consequences.
Description
Keywords
Metformin tablets; heavy metals; permissible daily exposure