[Self-medication in the treatment of acute malaria: study based on users of private health drug stores in Ouagadougou, Burkina Faso]. / Automédication dans le traitement de l'accès palustre: étude auprès de clients d'officines pharmaceutiques privées de la ville de Ouagadougou, Burkina Faso.

In order to contribute to the national debate on the change of protocol of the simple forms of malaria treatment in Burkina Faso, we conducted a transversal descriptive study among 397 private pharmacies users in Ouagadougou. The aims of the study were: - making an inventory of the antimalarials and signs which led to self-medication; - identifying the factors favouring self-treatment and the reasons why these antimalarials have been bought; - making an inventory of the misuses of antimalarial drugs by individuals practicing self-medication; - checking the knowledge base in individuals practicing self-medication in relation to resistance to antimalarials. We noticed that chloroquine (39.3%), sulfadoxine-pyrimethamin (24.4%), arthemisinin and its by products (15.1%) were the three main molecules which account for antimalarial self-treatment However the use of these molecules was inappropriate regarding the dosage (41.3%) as well as the rate of intake (40.7%). Self-medication was motivated by the common signs of malaria and the way in which this parasitosis has become an every day feature in people's minds. The choice of the molecule, the knowledge of the directions for use and the rate of intake were significantly linked to the level of education (p < 0.001). Self-medication being one of the major causes of resistance development, it is necessary together with local pharmacies retailers, to organize information campaigns on the correct use of molecules of the new antimalarial therapeutic scheme which will be adopted.

Stability parameter estimation at ambient temperature from studies at elevated temperatures.

The determination of specific kinetic constants k(i) in pH-profile studies is often undertaken at ambient temperature. However, when dealing with a drug substance that is stable at ambient temperature, the pH-profile study is conducted at a chosen elevated temperature and the kinetic parameters are given at this particular elevated temperature. But in stability studies we generally need kinetic constants at ambient or storage temperature for practical reasons (information and storage conditions of formulation). To assess this ambient kinetic information from studies at elevated temperatures, cumulative sequential steps are usually employed with very few statistical concerns on the final estimates. The statistical problems on these final estimates in cumulative procedures are highlighted in many papers. Because these stability parameters are useful for drug formulation and storage conditions, good practical decisions have to be made on the basis of statistically unbiased identified parameters. We propose in this paper a nonlinear model that allows the direct determination of specific activation energies E(ai) that are linked to the specific kinetic constants k(i). Hence, a mathematical relationship between drug concentration C, pH, temperature T, and time t is obtained. Kinetic data from acetylsalicylic acid (ASA) hydrolysis (first-order kinetics) are used to validate the model. The results show that it is possible to obtain directly, by an extrapolation procedure, the kinetic parameters (specific kinetic constants k(i), specific activation energies E(ai), and dissociation constant pK(a)) at low temperature from data gathered at elevated temperatures using more meaningful statistics.

Improved kinetic parameter estimation in pH-profile data treatment.

Statistical problems in temperature stability parameter estimation have been the subject of many papers whereas statistics in, pH-profile parameter estimation have focused little attention. However, the conventional two step method used in data treatment in both cases leads to identical statistical problems. The aim of this study is then to introduce a method that improves statistics in pH-profile parameter estimation. A one step non-linear method that takes into account the errors in drug content determination is proposed. A mathematical relationship between drug content C, pH and time t is tested. The proposed method allows the estimation of the specific kinetic constants and the dissociation constant (pK(a)) in a single run. The most likely experimental initial drug contents C(0j),. where j is the index of a given experiment, are also determined. This approach that takes into account all relevant experimental information for the estimation of kinetic parameters is more rigorous from a statistical viewpoint than the classical two step methods. Kinetic data from acetylsalicylic acid (ASA) hydrolysis was used for the tests.

Incorporating batch effects in the estimation of drug stability parameters using an Arrhenius model.

The nonlinear estimation of drug stability parameters (energy of activation Ea and shelf-life tY) by conventional approaches employs equations relating drug content determination C at time t and temperature T. The identification procedures lead to the determination of only one initial drug content C0 for several different experiments. However, it is well known that because of experimental concentration variation or of intentional modification of the experimental schedule, there are as many initial drug contents as experiments. For these reasons, a method which takes into account batch effects is proposed to determine stability parameters and also all initial drug contents C0j where j is the index of experiment in one step. This method is more accurate from a statistical viewpoint and is suitable for data treatment in pharmaceutical industries where the initial drug content of each batch entering the stability program can be checked a posteriori. The application of this method is shown on real kinetic data from the hydrolysis of acetylsalicylic acid (ASA).