Multi-Analytical Approach for Profiling Some Essential Medical Drugs

Abstract

Counterfeit and substandard pharmaceutical drugs are chiefly rampant in developing countries due to inadequate analytical facilities and lack of regulatory oversight. The production of counterfeit or substandard drugs is broadly problematic. Underestimating it therefore leads to morbidity, mortality, drug resistance, introduction of toxic substances into the body and loss of confidence in health care systems. Medical drugs that are often counterfeited range from antimalarial drugs to antiretroviral drugs with antibiotics being counterfeited the most. This research work, therefore, aims at contributing towards the establishment of measures/processes for distinguishing between fake and genuine amoxicillin drugs. This was achieved by the identification and quantification of the Active Pharmaceutical Ingredient (API) and the excipients in the drug formulation. The major analytical techniques employed for this research work were Instrumental Neutron Activation Analysis (INAA), X-ray Powder Diffraction (XRD), High Performance Liquid Chromatography (HPLC) and in vitro Dissolution Test. The amoxicillin samples analyzed were the foreign generic amoxicillin purchased from Ernest Chemists pharmacy at East Legon, Accra, the National Health Insurance Scheme (NHIS) amoxicillin purchased at Fair Mile pharmacy at West Legon, Accra and the Suspected Fake amoxicillin purchased at Okaishi market. For the establishment of fingerprint for identification of substandard amoxicillin, INAA was used to qualitatively determine the short lived radionuclides (excipients) which then facilitated the correct identification of the API and the excipient phases in each of the amoxicillin groups. The phases identified were Amoxicillin Trihydrate as the excipient, Magnesium Stearate (hydrated) and Magnesium Stearate (anhydrous) as the excipients. For Quality control purposes, High Performance Liquid Chromatography approach and also, the in vitro Dissolution test were conducted on each of the groups of amoxicillin samples. Before that, the Physical Parameter test on each revealed that, the British Pharmacopoeia (B.P ±7.5%) weight range for the Foreign Generic Amoxicillin was 0.6322 g – 0.7348 g, with the actual range being 0.6587 g – 0.7111 g. For the NHIS Amoxicillin, the B.P ±7.5% weight range was 0.4243 g – 0.4931 g with the actual range being 0.4313 g – 0.4824 g. The Suspected Fake Amoxicillin had a B.P ±7.5% weight range of 0.3733 g – 0.4339 g with its actual range being 0.3966 g – 0.4130 g. For the HPLC, The range of the percentage content of the API according to the 3rd edition of the British Pharmacopoeia is 92.5% - 110.0%. The Foreign Generic Amoxicillin contained 102.5% of the API, the NHIS Amoxicillin contained 99.8% of the API and the Suspected Fake Amoxicillin contained 98.7% of the API which all fall within the pharmacopoeia range. For the Dissolution Test, According to the 2014 edition of the British Pharmacopoeia, the threshold tolerance level is 80% below which a medical drug is rejected. The dissolution percentage range of the Foreign Generic Amoxicillin was 93.6% – 95.5%, that of the NHIS Amoxicillin was 87.5% – 92.0%, which were above the 80% tolerance level. But the dissolution percentage range of the Suspected Fake Amoxicillin was 55.7% – 57.2% which is far below the threshold tolerance level of 80% indicated. The Suspected Fake Amoxicillin was therefore found to be substandard. This research work has also shown that for quality control purposes, HPLC is a better tool but XRD in combination with INAA is a more effective tool for structural identification and phase quantification for the purposes of distinguishing between fake and genuine drugs. It also has faster analysis time, and simpler sample preparation.