Quality of the Antibiotics—Amoxicillin and Co-Trimoxazole from Ghana, Nigeria, and the United Kingdom

Abstract

Little is known about the quality of antibiotics despite being in high demand globally. Thirty five samples (27 brands) of the antibiotics amoxicillin (N = 20; 16 brands) and co-trimoxazole (N = 15; 11 brands), manufactured in six countries (China, Ghana, India, Ireland, Nigeria, and United Kingdom), were purchased in Ghana, Nigeria, and the United Kingdom. Their quality was assessed using German Pharma Health Fund (GPHF) MiniLab® as the screening tool—two capsules of amoxicillin (10%) and two tablets of co-trimoxazole (20%) failed the thin-layer chromatography (TLC) test. Definitive drug quality was measured using high-performance liquid chromatography–photodiode array detection (HPLC-PDA) for content of the stated active pharmaceutical ingredients (APIs) and bioavailability was determined with in vitro dissolution testing. All the samples of amoxicillin complied with U.S. Pharmacopeia (USP) tolerance limits, but 60% tablets of co-trimoxazole (purchased in Ghana and Nigeria) did not. There was disparity in the results obtained for co-trimoxazole and amoxicillin samples using the MiniLab® TLC tests. This highlights the need to invest in techniques such as HPLC-PDA and dissolution testing alongside the screening tests for assessing drug quality.

Assessment of the quality of anti-tuberculosis medicines in Almaty, Kazakhstan, 2014

“…In particular, disintegration, although an important forerunner to dissolution (and subsequent bioavailability), may not accurately predict the bioavailability of all drugs or forms, notably RMP. According to the semi-quantitative TLC component of GPHF-Minilab, 21,22 drugs with at least 80% of the API would pass the test. Given that ±10%variations in TLC readings can be seen with the naked eye, medicines with 70–80% of the API that otherwise meet quality standards could be acceptable.…”

“…Given that ±10%variations in TLC readings can be seen with the naked eye, medicines with 70–80% of the API that otherwise meet quality standards could be acceptable. 21,23,24 However, as TLC may mistakenly identify a form as having too little or sufficient API, reader experience is important for accurate interpretation. 24 Conversely, the detection of breakdown products of the API by TLC due to, for example, incorrect storage, can lend confidence to an interpretation of too little drug.…”

Substandard and falsified medicine screening technologies

“…Minilab can be used for chemical and physical analysis, employing thin layer chromatography (TLC) and disintegration techniques, respectively. Minilab has been used extensively for PMS around the world and has been supplied to 97 countries (Batson et al 2016;Fadeyi et al 2015;GPHF 2019;Kaale et al 2016;Lalani et al 2015;Petersen et al 2017). TLC is a semi-quantitative technique that separates components in a sample according to differences in polarity, as the components interact between mobile and stationary phases.…”

Once-daily amoxicillin immediate- and extended-release bilayer tablets

“…Amoxicillin is a semi-synthetic, broad-spectrum beta-lactam antibiotic [1,2]. It is widely used because of its strong inhibitory effects against a wide range of both Gram-positive and Gram-negative bacteria [3,4].…”