title: Simultaneous liquid chromatographic analysis of ritonavir, quinine and 3-hydroxyquinine in human plasma.
abstract: In regions with high prevalence of HIV and malaria, co-infection of both diseases is common; hence, there is a high possibility of concurrent administration of antiretroviral and antimalarial drugs. This study describes a new ion-pair reversed-phase high-performance liquid chromatographic (HPLC) method for simultaneous determinations of ritonavir (RTV), quinine (QN), and its major metabolite, 3-hydroxyquinine (3-HQN), in human plasma. Following a simple extraction with diethyl-ether under alkaline conditions, chromatographic separation was achieved on a 5-mum particle size C-18 column (200 mm x 4.6mm I.D.) using a mobile phase consisting of methanol:acetonitrile:0.02 M potassium dihydrogen phosphate (15:10:75) containing 75 mmol/L perchloric acid (pH 2.8). Retention times for RTV, 3-HQN, QN and the internal standard were 2.8, 4.0, 7.0 and 12 min, respectively. The limits of detection and validated lower limits of quantitation were 10 and 12.5 ng/ml for RTV while the corresponding values were 5 and 70 ng/ml for both QN and 3-HQN, respectively. The new HPLC method is simple, rapid, selective, reproducible and cost-effective. As demonstrated in three volunteers, it will facilitate the conducting of simultaneous therapeutic monitoring of quinine and ritonavir in patients concurrently receiving both drugs.
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria.
authors.forename: Julius O
authors.initials: JO
authors.lastname: Soyinka
authors.forename: Cyprian O
authors.initials: CO
authors.lastname: Onyeji
authors.forename: Sharon I
authors.initials: SI
authors.lastname: Omoruyi
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D011802:Quinidine / Q000031:analogs & derivatives* / Q000097:blood; D011803:Quinine / Q000097:blood*; D012015:Reference Standards; D019438:Ritonavir / Q000097:blood*; D012680:Sensitivity and Specificity
chemical_list: C013569:3-hydroxyquinidine; D011803:Quinine; D011802:Quinidine; D019438:Ritonavir