The study addressed the following research questions:
• Is there a problem of poor quality of chloroquine tablets and syrup formulations and of sulphadoxine/pyrimethamine tablets in countries where they are used?
• If so, what is the magnitude of this problem?
• Is the problem limited to a particular level of the distribution chain?
Study design and sampling
The most widely used antimalarials, chloroquine and sulpha-doxine/pyrimethamine were evaluated. Two dosage forms, tablets and syrup, were sampled for chloroquine (CQT and CQS respectively) while only the tablet form of sulphadoxine/pyrimethamine were sampled (SPT). The study was designed to collect samples at various levels of the drug distribution chain, such as medical stores, teaching hospitals, district hospitals, health centres, private sector pharmacies, shops, street vendors and households. Quality indicators measured were the content of the active ingredient and dissolution rate (for tablets only) in comparison to standard specifications for these products in the relevant pharmacopoeia.
Eight African countries, Gabon, Ghana, Kenya, Mali, Mozambique, Sudan, the United Republic of Tanzania and Zimbabwe were chosen to participate in the study. A team leader was chosen from each country to coordinate sample collection following the standard sampling protocol, coding and packaging for transportation to the WHO/AFRO Regional Adviser through the WHO country office.
The sample identification system was based upon an agreed coding method for all the countries involved in the study. Samples were collected at the various levels of the distribution chain (see list above). Each participating country collected a minimum of 20 samples of each of the three drug products. The sample collectors adopted the actual quantities from each level to their local situation using the following suggested steps:
• Identify the level and institution from which samples will be collected.
• Visit the authorities at the institution and household and acquaint them with the purpose and importance of the study, as well as the information that will be collected.
• Agree on the basis for replacement of drugs to be obtained as samples, if necessary.
• Define sample identification and coding.
• Obtain standardized packaging for samples.
• Collect and carefully label samples at the point of collection.
• Collate all the samples, prepare them for dispatch and deposit them with the WHO country office for onward freighting to WHO/AFRO.
• Send a summary of the sample dispatch report, including coding, to the team leader.
Information obtained for each sample included the name of the drug (brand or generic), strength, dosage form, date of manufacture, date of expiry, description of packaging material, any remarks on storage, location of sample collection point, and date of sample collection. Information on expiry dates was not consistently available and therefore it was not recorded as part of the study.
The samples were sent to the WHO/AFRO Regional Office, and then channelled to the Centre for Quality Assurance of Medicines (CENQAM) in Potchefstroom, South Africa, for analysis.
Analysis of samples
Samples were analysed according to pharmacopoeial specifications to assess the quality of the products. Tests were on the content of active pharmaceutical ingredient for tablets and syrup, and dissolution and content for tablets.