Browsing by Subject "Amodiaquine"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Open Access
    Effects of amodiaquine and artesunate on sulphadoxine-pyrimethamine pharmacokinetic parameters in children under five in Mali
    (BioMed Central Ltd, 2011) Tekete, Mamadou; Toure, Sekou; Fredericks, Alfia; Beavogui, Abdoul; Sangare, Cheick; Evans, Alicia; Smith, Peter; Maiga, Hamma; Traore, Zoumana; Doumbo, Ogobara; Barnes, Karen; Djimde, Abdoulaye
    BACKGROUND:Sulphadoxine-pyrimethamine, in combination with artesunate or amodiaquine, is recommended for the treatment of uncomplicated malaria and is being evaluated for intermittent preventive treatment. Yet, limited data is available on pharmacokinetic interactions between these drugs. METHODS: In a randomized controlled trial, children aged 6-59 months with uncomplicated falciparum malaria, received either one dose of sulphadoxine-pyrimethamine alone (SP), one dose of SP plus three daily doses of amodiaquine (SP+AQ) or one dose of SP plus 3 daily doses of artesunate (SP+AS). Exactly 100 mul of capillary blood was collected onto filter paper before drug administration at day 0 and at days 1, 3, 7, 14, 21 and 28 after drug administration for analysis of sulphadoxine and pyrimethamine pharmacokinetic parameters. RESULTS: Fourty, 38 and 31 patients in the SP, SP+AQ and SP+AS arms, respectively were included in this study. The concentrations on day 7 (that are associated with therapeutic efficacy) were similar between the SP, SP+AQ and SP+AS treatment arms for sulphadoxine (median [IQR] 35.25 [27.38-41.70], 34.95 [28.60-40.85] and 33.40 [24.63-44.05] mug/mL) and for pyrimethamine (56.75 [46.40-92.95], 58.75 [43.60-98.60] and 59.60 [42.45-86.63] ng/mL). There were statistically significant differences between the pyrimethamine volumes of distribution (4.65 [3.93-6.40], 4.00 [3.03-5.43] and 5.60 [4.40-7.20] L/kg; p = 0.001) and thus elimination half-life (3.26 [2.74 -3.82], 2.78 [2.24-3.65] and 4.02 [3.05-4.85] days; p < 0.001). This study confirmed the lower SP concentrations previously reported for young children when compared with adult malaria patients. CONCLUSION: Despite slight differences in pyrimethamine volumes of distribution and elimination half-life, these data show similar exposure to SP over the critical initial seven days of treatment and support the current use of SP in combination with either AQ or AS for uncomplicated falciparum malaria treatment in young Malian children.
  • Thumbnail Image
    Item
    Restricted
    Quinoline antimalarials decrease the rate of beta-hematin formation
    (Elsevier, 2005) Egan, Timothy J; Ncokazi, Kanyile K
    The strength of inhibition of b-hematin (synthetic hemozoin or malaria pigment) formation by the quinoline antimalarial drugs chloroquine, amodiaquine, quinidine and quinine has been investigated as a function of incubation time. In the assay used, b-hematin formation was brought about using 4.5 M acetate, pH 4.5 at 60 C. Unreacted hematin was detected by formation of a spectroscopically distinct low spin pyridine complex. Although, these drugs inhibit b-hematin formation when relatively short incubation times are used, it was found that b-hematin eventually forms with longer incubation periods (8 h for quinine). This conclusion was supported by both infrared and X-ray powder diffraction observations. It was further found that the IC50 for inhibition of b-hematin formation increases markedly with increasing incubation times in the case of the 4-aminoquinolines chloroquine and amodiaquine. By contrast, in the presence of the quinoline methanols quinine and quinidine the IC50 values increase much more slowly. This results in a partial reversal of the order of inhibition strengths at longer incubation times. Scanning electron microscopy indicates that b-hematin crystals formed in the presence of chloroquine are more uniform in both size and shape than those formed in the absence of the drug, with the external morphology of these crystallites being markedly altered. The findings suggest that these drugs act by decreasing the rate of hemozoin formation, rather than irreversibly blocking its formation. This model can also explain the observation of a sigmoidal dependence of b-hematin inhibition on drug concentration.