Primaquine decreased plasma concentration of ritonavir: single- and repeated-dose study in Sprague Dawley rats
Background: The present study was aimed to explore the effects of ritonavir and primaquine combination given as a singledoseÂ or repeated-dose compared to ritonavir alone on ritonavir plasma concentration in the rats.
Methods: In single-dose study, 30 male Spraque Dawley rats were randomly allocated to receive ritonavir 20 mg/kg BW orÂ ritonavir 20 mg/kg BW + primaquine 1.2 mg/kg BW or ritonavir 20 mg/kg BW + ketokonazole 10 mg/kg BW. KetokonazoleÂ was used as positive control of ritonavir metabolism inhibitor. In the repeated-dose study, thirty Spraque Dawley male ratsÂ were randomly allocated to receive ritonavir 20 mg/kg BW/day or ritonavir 20 mg/kg BW/day + primaquine 1.2 mg/kg BW/day or ritonavir 20 mg/kg BW/day + rifampicin 100 mg/kg BW/day. Rifampicin was used as a positive control of ritonavirÂ metabolism inducer.
Results: In the single-dose study, ketokonazole increased the area under the plasma concentration (AUC) of ritonavir (â114.8%, p< 0.05), while primaquine tended to decrease the AUC of ritonavir (â 32.6%, p> 0.05). Repeated-dose studyÂ showed that rifampicin decreases the AUC of ritonavir (â 42.8%, p< 0.001), and primaquine decreased the AUC of ritonavirÂ plasma concentration (â 46.6%, p< 0.001).
Conclusion: Concomitant administration of primaquine and ritonavir decreases the AUC of ritonavir. This effect may resultÂ in the insufficient concentration of ritonavir as anti-HIV, which may lead to treatment failure with ritonavir. (Med J IndonesÂ 2011; 20:190-4)
Keywords: drug interaction, metabolism, primaquine, ritonavir
Copyright (c) 2011 Melva Louisa, Vivian Soetikno, Nafrialdi Nafrialdi, Rianto Setiabudy, Frans D. Suyatna
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