Resistance against anti-malarial drugs remains one of the greatest obstacles to the effective control of malaria. The current first-line treatment regimen for uncomplicated P.falciparum malaria is based on artemisinin combination therapies (ACTs). However, reports of an increase in tolerance of the malaria parasite to artemisinins used in ACTs have alarmed the malaria community. The spread of artemisinin-resistant parasites would impact negatively on malaria control. Chloroquine and amodiaquine are 4-aminoquinolines. Chloroquine and amodiaquine were evaluated in a primate model by comparing the bioavailability of these compounds in a reference formulation and also in a Pheroid® formulation. In vivo pharmacokinetic studies were conducted for chloroquine, and in vitro and in vivo drug metabolism and pharmacokinetic (DMPK) studies were conducted for amodiaquine. Pheroid® technology forms the basis of a colloidal drug delivery system, and it is the potential application of this technology in combination with the 4-aminoquinolines that was the focus of this thesis. Pheroid® is a registered trademark but for ease of reading will be referred to as pheroid(s) or pro-pheroid(s) throughout the rest of the thesis. The non-human primate model used for evaluation of the pharmacokinetic parameters was the vervet monkey (Chlorocebus aethiops). Chloroquine was administered orally at 20 mg/kg. A sensitive and selective LC-MS/MS method was developed to analyze the concentration of chloroquine in both whole blood and plasma samples. The Cmax obtained for whole blood was 1039 ± 251.04 ng/mL for the unformulated reference sample of chloroquine and 1753.6 ± 382.8 ng/mL for the pheroid formulation. The AUC0-inf was 37365 ± 6383 ng.h/mL (reference) and 52047 ± 11210 ng.h/mL (pheroid). The results indicate that the use of pheroid technology enhances the absorption of chloroquine. The effect of pheroid technology on the bioavailability of amodiaquine and N-desethylamodiaquine was determined in two groups of vervet monkeys, with the reference group receiving capsules containing the hydrochloride salt of amodiaquine and the test group receiving capsules containing a pro-pheroid formulation of amodiaquine. Amodiaquine was administered at 60 mg/kg. Blood concentrations of amodiaquine and N-desethylamodiaquine samples were monitored over 13 time points from 0.5 to 168 hours. Amodiaquine and pro-pheroid formulated amodiaquine were incubated in vitro with human and monkey liver (HLM and MLM) and intestinal (HIM and MIM) microsomes and recombinant cytochrome P450 enzymes. The in vitro metabolism studies confirm the rapid metabolism of amodiaquine to the main metabolite N-desethylamodiaquine in monkeys. Although the pharmacokinetic parameters varied greatly, parameters for both the parent compound and main metabolite were lower in the test formulation compared to the reference formulation. For HLM, MLM and CYP2C8, the pro-pheroid test formulation showed significantly longer amodiaquine clearance and slower formation of N-desethylamodiaquine. However, the effect was reversed in MIM. Pheroid technology impacts differently on the bioavailability of the various pharmaceutical classes of anti-malarials. Pheroid technology did not enhance the bioavailability of amodiaquine or N-desethylamodiaquine. This is contrary to the observed effects of pheroid technology on the pharmacokinetics of other drugs such as artemisone and chloroquine where it increases the area under the curve and prolongs the drug half-life. / Thesis (PhD (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

Resistance against anti-malarial drugs remains one of the greatest obstacles to the effective control of malaria. The current first-line treatment regimen for uncomplicated P.falciparum malaria is based on artemisinin combination therapies (ACTs). However, reports of an increase in tolerance of the malaria parasite to artemisinins used in ACTs have alarmed the malaria community. The spread of artemisinin-resistant parasites would impact negatively on malaria control. Chloroquine and amodiaquine are 4-aminoquinolines. Chloroquine and amodiaquine were evaluated in a primate model by comparing the bioavailability of these compounds in a reference formulation and also in a Pheroid® formulation. In vivo pharmacokinetic studies were conducted for chloroquine, and in vitro and in vivo drug metabolism and pharmacokinetic (DMPK) studies were conducted for amodiaquine. Pheroid® technology forms the basis of a colloidal drug delivery system, and it is the potential application of this technology in combination with the 4-aminoquinolines that was the focus of this thesis. Pheroid® is a registered trademark but for ease of reading will be referred to as pheroid(s) or pro-pheroid(s) throughout the rest of the thesis. The non-human primate model used for evaluation of the pharmacokinetic parameters was the vervet monkey (Chlorocebus aethiops). Chloroquine was administered orally at 20 mg/kg. A sensitive and selective LC-MS/MS method was developed to analyze the concentration of chloroquine in both whole blood and plasma samples. The Cmax obtained for whole blood was 1039 ± 251.04 ng/mL for the unformulated reference sample of chloroquine and 1753.6 ± 382.8 ng/mL for the pheroid formulation. The AUC0-inf was 37365 ± 6383 ng.h/mL (reference) and 52047 ± 11210 ng.h/mL (pheroid). The results indicate that the use of pheroid technology enhances the absorption of chloroquine. The effect of pheroid technology on the bioavailability of amodiaquine and N-desethylamodiaquine was determined in two groups of vervet monkeys, with the reference group receiving capsules containing the hydrochloride salt of amodiaquine and the test group receiving capsules containing a pro-pheroid formulation of amodiaquine. Amodiaquine was administered at 60 mg/kg. Blood concentrations of amodiaquine and N-desethylamodiaquine samples were monitored over 13 time points from 0.5 to 168 hours. Amodiaquine and pro-pheroid formulated amodiaquine were incubated in vitro with human and monkey liver (HLM and MLM) and intestinal (HIM and MIM) microsomes and recombinant cytochrome P450 enzymes. The in vitro metabolism studies confirm the rapid metabolism of amodiaquine to the main metabolite N-desethylamodiaquine in monkeys. Although the pharmacokinetic parameters varied greatly, parameters for both the parent compound and main metabolite were lower in the test formulation compared to the reference formulation. For HLM, MLM and CYP2C8, the pro-pheroid test formulation showed significantly longer amodiaquine clearance and slower formation of N-desethylamodiaquine. However, the effect was reversed in MIM. Pheroid technology impacts differently on the bioavailability of the various pharmaceutical classes of anti-malarials. Pheroid technology did not enhance the bioavailability of amodiaquine or N-desethylamodiaquine. This is contrary to the observed effects of pheroid technology on the pharmacokinetics of other drugs such as artemisone and chloroquine where it increases the area under the curve and prolongs the drug half-life. / Thesis (PhD (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

Malaria is currently a huge treat worldwide, as far as infections are concerned, and is responsible for thousands of deaths per annum. The dilemma associated with the development of anti–malarial drug resistance over the past few decades should be addressed as a matter of urgency. Novel drug delivery systems should be developed in order to employ new and existing anti–malarial drugs in the treatment and management of malaria. The aim of these delivery systems should include an improvement in the efficacy, specificity, acceptability and therapeutic index of anti–malarial drugs. Previous studies have suggested that liposomes have the ability to encapsulate, protect and to promote the sustained release of anti–malarial drugs. Two liposome formulations, namely liposomes and chloroquine entrapped in liposomes, were formulated during this thesis and evaluated by conducting a stability study and an in vitro study with the main focus on cell viability. The stability study consisted of a series of stability tests regarding the stability of nine liposome and nine chloroquine entrapped in liposome formulations over a period of twelve weeks. The in vitro study included three assays such as a reactive oxygen species assay, a lipid peroxidation assay and a hemolysis assay. The aims of these studies included the manufacturing of liposomes, the incorporation of chloroquine into liposomes, the determination of the stability of the formulations as well as the evaluation of the possible in vitro toxicity of liposomes. Results obtained from these studies revealed that liposomes remained more stable over the stability study period in comparison to chloroquine entrapped in liposomes. The entrapment of chloroquine within liposomes was possible, although the initial entrapment efficiency (%) of 14.55 % was much too low. The production of reactive oxygen species occurred to a small extent in the red blood cells and the infected red blood cells. Equal amounts of reactive oxygen species (%) was observed within both the red blood cells and the infected red blood cells with a maximum value of 23.27 % in the presence of the chloroquine entrapped in liposomes at varying concentrations. Red blood cells experienced the highest degree of lipid peroxidation (%) in the presence of chloroquine, at varying concentrations, entrapped in liposomes. The maximum amount of lipid peroxidation (%) was 79.61 %. No significant degree of hemolysis (%) was observed in the red blood cells neither in the presence of the liposomes nor in the presence of the chloroquine entrapped in liposomes at varying concentrations. It can be concluded that liposomes are a more stable formulation and have less toxic effects on red blood cells and infected red blood cells in comparison to the chloroquine entrapped in liposome formulations. Future studies should investigate the possibility of a more stable and less toxic chloroquine entrapped in liposome formulation. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2011.

Malaria is currently a huge treat worldwide, as far as infections are concerned, and is responsible for thousands of deaths per annum. The dilemma associated with the development of anti–malarial drug resistance over the past few decades should be addressed as a matter of urgency. Novel drug delivery systems should be developed in order to employ new and existing anti–malarial drugs in the treatment and management of malaria. The aim of these delivery systems should include an improvement in the efficacy, specificity, acceptability and therapeutic index of anti–malarial drugs. Previous studies have suggested that liposomes have the ability to encapsulate, protect and to promote the sustained release of anti–malarial drugs. Two liposome formulations, namely liposomes and chloroquine entrapped in liposomes, were formulated during this thesis and evaluated by conducting a stability study and an in vitro study with the main focus on cell viability. The stability study consisted of a series of stability tests regarding the stability of nine liposome and nine chloroquine entrapped in liposome formulations over a period of twelve weeks. The in vitro study included three assays such as a reactive oxygen species assay, a lipid peroxidation assay and a hemolysis assay. The aims of these studies included the manufacturing of liposomes, the incorporation of chloroquine into liposomes, the determination of the stability of the formulations as well as the evaluation of the possible in vitro toxicity of liposomes. Results obtained from these studies revealed that liposomes remained more stable over the stability study period in comparison to chloroquine entrapped in liposomes. The entrapment of chloroquine within liposomes was possible, although the initial entrapment efficiency (%) of 14.55 % was much too low. The production of reactive oxygen species occurred to a small extent in the red blood cells and the infected red blood cells. Equal amounts of reactive oxygen species (%) was observed within both the red blood cells and the infected red blood cells with a maximum value of 23.27 % in the presence of the chloroquine entrapped in liposomes at varying concentrations. Red blood cells experienced the highest degree of lipid peroxidation (%) in the presence of chloroquine, at varying concentrations, entrapped in liposomes. The maximum amount of lipid peroxidation (%) was 79.61 %. No significant degree of hemolysis (%) was observed in the red blood cells neither in the presence of the liposomes nor in the presence of the chloroquine entrapped in liposomes at varying concentrations. It can be concluded that liposomes are a more stable formulation and have less toxic effects on red blood cells and infected red blood cells in comparison to the chloroquine entrapped in liposome formulations. Future studies should investigate the possibility of a more stable and less toxic chloroquine entrapped in liposome formulation. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2011.