A Nationwide Survey of the Quality of Antimalarials in Retail Outlets in Tanzania

Abstract

IntroductionRetail pharmaceutical products are commonly used to treat fever and malaria in sub-Saharan African countries. Small scale studies have suggested that poor quality antimalarials are widespread throughout the region, but nationwide data are not available that could lead to generalizable conclusions about the extent to which poor quality drugs are available in African communities. This study aimed to assess the quality of antimalarials available from retail outlets across mainland Tanzania.Methods and FindingsWe systematically purchased samples of oral antimalarial tablets from retail outlets across 21 districts in mainland Tanzania in 2005. A total of 1080 antimalarial formulations were collected including 679 antifol antimalarial samples (394 sulfadoxine/pyrimethamine and 285 sulfamethoxypyrazine/pyrimethamine), 260 amodiaquine samples, 63 quinine samples, and 51 artemisinin derivative samples. A systematic subsample of 304 products was assessed for quality by laboratory based analysis to determine the amount of the active ingredient and dissolution profile by following the published United States Pharmacopoeia (USP) monogram for the particular tablet being tested. Products for which a published analytical monogram did not exist were assessed on amount of active ingredient alone. Overall 38 or 12.2% of the samples were found to be of poor quality. Of the antifolate antimalarial drugs tested 13.4% were found to be of poor quality by dissolution and content analysis using high-performance liquid chromatography (HPLC). Nearly one quarter (23.8%) of quinine tablets did not comply within the tolerance limits of the dissolution and quantification analysis. Quality of amodiaquine drugs was relatively better but still unacceptable as 7.5% did not comply within the tolerance limits of the dissolution analysis. Formulations of the artemisinin derivatives all contained the stated amount of active ingredient when analysed using HPLC alone.ConclusionsSubstandard antimalarial formulations were widely available in Tanzania at the time of this study. No products were detected that did not contain any amount of the stated active ingredient. Quinine and sulfadoxine/pyrimethamine products were the most widely available and also the most likely to be of poor quality. Substandard products were identified in all parts of the country and were labeled as made by both domestic and international manufacturers. With the expansion of the retail pharmaceutical sector as a delivery channel for antimalarial formulations the need for regular nationwide monitoring of their quality will become increasingly important.

Substandard and counterfeit medicines: a systematic review of the literature

“…Only four studies used random sampling methods, in which investigators collected samples from outlets that were randomly chosen from a complete or registered list or outlets in a defined area 16 17 19 22. Information on the person collecting the samples was provided by 12 studies 15 17–23 25–28.…”

Substandard/Counterfeit Antimicrobial Drugs

“…(15), the prevalence of substandard/counterfeit antimicrobials varied from 10% to more than 50% in some studies (2,7,38,79,80), whereas in another report it was 28.5% (range, 11 to 48%) and was similar in developing countries (22 to 38%). In the latter review, out of a total of 44 identified studies, only 15 studies were included in the analysis based on quality criteria (59), four used random sampling methods (7,28,81,82), and only one included sample size estimates (81). Packaging analysis of the collected samples was performed in only two studies from Southeast Asia (40,58).…”

“…Numerous antibiotics have been reported to have low quality (76)(77)(78)(79)(80)(81)(82)(83)(84)(85)(86) (Tables 4 and 5). In a recent literature review, out of 163 counterfeit antibiotics detected in the world until 2009, 50% were beta-lactams, 12% quinolones, 11% macrolides, lincosamides, and synergistines, 7% cyclins, and 20% other antibiotics (17).…”

Risks Associated with International Trading of Medicines by Non-Licensed Entities and Non-Professionals

“…However, due to incorrect storage, inadequate handling and improper transportation, their quality may deteriorate rapidly to the extent that by the time they reach the street vendors, they are already as good as impotent products. Several studies have reported how heat-sensitive medicines, notably, vaccines, antibiotics and anti-malaria products have been transported and stored in inappropriate conditions leading them to degrade [62,66,83,84].…”