Skin cancer is the most widely diagnosed form of cancer and it is split in to non-melanoma skin cancer (NMSC) and cutaneous malignant melanoma (CMM). Cutaneous melanoma has a high propensity for malignancy and it has the highest mortality rate of all skin cancers (de Gruijl, 1999:2004). The first line of treatment for most skin cancers is surgical excision but instances do arise in which surgery is not feasible due to the health of the patient or the location of the lesion. Therefore, viable alternatives are necessary in cases where surgery is not possible (Telfer et al., 2008:36). The skin is readily available for delivery of cytotoxic drugs to treat carcinomas and melanomas so the topical delivery of 5-fluorouracil was investigated in this study. 5-Fluorouracil is a pyrimidine anti-metabolite which interferes with deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) synthesis by inhibiting the nucleotide synthetic enzyme thymidylate synthase (TS) and by becoming misincorporated into RNA and DNA. Thymidylate is essential for replication as well as repair of DNA, in the event of TS inhibition thymidylate is not formed and “thymineless deaths” of cells occur (Chu & Sartorelli, 2009:935; Longley et al., 2003:330). This active pharmaceutical ingredient (API) causes death of atypical and rapidly dividing cells (Tsuji & Karasek, 1986:474). The intravenous and topical routes are approved for 5-fluorouracil and in the case of skin cancer the obvious choice would be topical application (Chu & Sartorelli, 2009:935). Topical application of 5-fluorouracil results in the occurrence of terrible side effects such as severe inflammation, stomatitis, photosensitivity and dermatitis. A reduction in side effects would reduce the stigma associated with topical 5-fluorouracil and in turn increase patient compliance. Topical drug delivery entails the delivery of an API onto or into the various layers of the skin (Flynn & Weiner, 1993:33) in order to treat conditions on or within the skin. Topical application of APIs is non-invasive, painless and simple plus the target site is readily accessible for topical therapy, thus the API is delivered directly to the site of action (Naik et al., 2000:318). In the case of skin cancer, 5-fluorouracil should be able to reach the epidermis because NMSC originates from the keratinocytes (Marks & Hanson, 2010:305) and CMM from melanocytes (de Gruijl, 1999:2004) which are both found in the epidermis. The barrier function of the skin limits the penetration of molecules into the skin and the rate-limiting step is usually penetration into the stratum corneum (Foldvari, 2000:418). The aim of this study was to investigate the diffusion of 5-fluorouracil from formulations into and through the skin. Two physico-chemical properties of 5-fluorouracil that influence skin permeation were determined (aqueous solubility and n-octanol-buffer partition coefficient (log D)). The Pheroid™ drug delivery system was used to enhance the delivery of 5-fluorouracil (Grobler et al., 2008:284). Pheroid™ is a novel technology that is used in the delivery of APIs in pharmaceutical products. It enhances the efficacy of delivered compounds while allowing for the reduction of unwanted adverse effects (Grobler et al., 2008:284). Franz cell skin diffusion studies and tape-stripping were conducted with Pheroid™ and non-Pheroid™ formulations to allow for comparison and determination of the effect of Pheroid™. The in vitro efficacy of 5-fluorouracil in inducing apoptosis of human melanoma cells was investigated using a flow cytometric apoptosis assay. Different concentrations of 5-fluorouracil in formulation were utilised in the experiments so as to observe the cytotoxic effect of 5-fluorouracil. The effect of the drug delivery vehicle on the efficacy of 5-fluorouracil was investigated by utilising API solutions in addition to Pheroid™ and non-Pheroid™ formulations in the experiments. Relatively high concentrations of 5-fluorouracil diffused into and through the skin with Pheroid™ formulations resulting in a greatly enhanced in vitro skin permeation of 5-fluorouracil. The tape-stripping revealed that the Pheroid™ lotions resulted in higher concentrations of 5-fluorouracil in the epidermis and dermis after 12 h as compared to the lotions. There was no deducible trend with respect to the distribution of 5-fluorouracil between the epidermis and dermis. Subsequent to the apoptosis assay it was found that 5-fluorouracil was able to induce apoptosis in A375 cells after a 24 h incubation period. The Pheroid™ treatment of cells resulted in a greater response (mean fluorescence intensity) as compared to treatments with the other drug delivery vehicles at three of the four concentrations. This showed that the drug delivery vehicle played a role in the in vitro efficacy of 5-fluorouracil. Further research must be done in order to combine these results. Optimum and highly effective topical formulations with low doses of 5-fluorouracil must be formulated for the purpose of treating cutaneous cancers with a reduced incidence of side effects. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

Skin cancer is the most widely diagnosed form of cancer and it is split in to non-melanoma skin cancer (NMSC) and cutaneous malignant melanoma (CMM). Cutaneous melanoma has a high propensity for malignancy and it has the highest mortality rate of all skin cancers (de Gruijl, 1999:2004). The first line of treatment for most skin cancers is surgical excision but instances do arise in which surgery is not feasible due to the health of the patient or the location of the lesion. Therefore, viable alternatives are necessary in cases where surgery is not possible (Telfer et al., 2008:36). The skin is readily available for delivery of cytotoxic drugs to treat carcinomas and melanomas so the topical delivery of 5-fluorouracil was investigated in this study. 5-Fluorouracil is a pyrimidine anti-metabolite which interferes with deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) synthesis by inhibiting the nucleotide synthetic enzyme thymidylate synthase (TS) and by becoming misincorporated into RNA and DNA. Thymidylate is essential for replication as well as repair of DNA, in the event of TS inhibition thymidylate is not formed and “thymineless deaths” of cells occur (Chu & Sartorelli, 2009:935; Longley et al., 2003:330). This active pharmaceutical ingredient (API) causes death of atypical and rapidly dividing cells (Tsuji & Karasek, 1986:474). The intravenous and topical routes are approved for 5-fluorouracil and in the case of skin cancer the obvious choice would be topical application (Chu & Sartorelli, 2009:935). Topical application of 5-fluorouracil results in the occurrence of terrible side effects such as severe inflammation, stomatitis, photosensitivity and dermatitis. A reduction in side effects would reduce the stigma associated with topical 5-fluorouracil and in turn increase patient compliance. Topical drug delivery entails the delivery of an API onto or into the various layers of the skin (Flynn & Weiner, 1993:33) in order to treat conditions on or within the skin. Topical application of APIs is non-invasive, painless and simple plus the target site is readily accessible for topical therapy, thus the API is delivered directly to the site of action (Naik et al., 2000:318). In the case of skin cancer, 5-fluorouracil should be able to reach the epidermis because NMSC originates from the keratinocytes (Marks & Hanson, 2010:305) and CMM from melanocytes (de Gruijl, 1999:2004) which are both found in the epidermis. The barrier function of the skin limits the penetration of molecules into the skin and the rate-limiting step is usually penetration into the stratum corneum (Foldvari, 2000:418). The aim of this study was to investigate the diffusion of 5-fluorouracil from formulations into and through the skin. Two physico-chemical properties of 5-fluorouracil that influence skin permeation were determined (aqueous solubility and n-octanol-buffer partition coefficient (log D)). The Pheroid™ drug delivery system was used to enhance the delivery of 5-fluorouracil (Grobler et al., 2008:284). Pheroid™ is a novel technology that is used in the delivery of APIs in pharmaceutical products. It enhances the efficacy of delivered compounds while allowing for the reduction of unwanted adverse effects (Grobler et al., 2008:284). Franz cell skin diffusion studies and tape-stripping were conducted with Pheroid™ and non-Pheroid™ formulations to allow for comparison and determination of the effect of Pheroid™. The in vitro efficacy of 5-fluorouracil in inducing apoptosis of human melanoma cells was investigated using a flow cytometric apoptosis assay. Different concentrations of 5-fluorouracil in formulation were utilised in the experiments so as to observe the cytotoxic effect of 5-fluorouracil. The effect of the drug delivery vehicle on the efficacy of 5-fluorouracil was investigated by utilising API solutions in addition to Pheroid™ and non-Pheroid™ formulations in the experiments. Relatively high concentrations of 5-fluorouracil diffused into and through the skin with Pheroid™ formulations resulting in a greatly enhanced in vitro skin permeation of 5-fluorouracil. The tape-stripping revealed that the Pheroid™ lotions resulted in higher concentrations of 5-fluorouracil in the epidermis and dermis after 12 h as compared to the lotions. There was no deducible trend with respect to the distribution of 5-fluorouracil between the epidermis and dermis. Subsequent to the apoptosis assay it was found that 5-fluorouracil was able to induce apoptosis in A375 cells after a 24 h incubation period. The Pheroid™ treatment of cells resulted in a greater response (mean fluorescence intensity) as compared to treatments with the other drug delivery vehicles at three of the four concentrations. This showed that the drug delivery vehicle played a role in the in vitro efficacy of 5-fluorouracil. Further research must be done in order to combine these results. Optimum and highly effective topical formulations with low doses of 5-fluorouracil must be formulated for the purpose of treating cutaneous cancers with a reduced incidence of side effects. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

The aim of this study was to investigate in vitro transdermal diffusion of a small peptide namely arginine vasopressin (AVP) with the aid of the novel PheroidTM drug delivery system. Generally, peptides seem unfit for transdermal permeation, but it was thought prudent to explore the suitability of this lipid-based system after success was achieved with entrapment of tuberculostatics, bacteria and viruses. Bestatin (a selective aminopeptidase inhibitor) was employed to circumvent any skin-related degradation of the active. Therefore, the effect of bestatin on the preservation of AVP during diffusion was investigated. Vertical Franz cell diffusion studies were conducted with female abdominal skin, with AVP at a concentration of 150 pglml in the donor phase and Hepes buffer as the receptor phase over a twelve-hour period. To prove entrapment of AVP within the lipid structures of the PheroidsTM, fluorescentlylabelled samples were monitored by means of confocal laser scanning microscopy (CLSM), which revealed definite entrapment. In vitro permeation profiles for AVP exhibited a biphasic character, with the majority of permeation occurring during the first two hours. The PheroidTM delivery system proved to be advantageous when applied as delivery medium. The inclusion of bestatin has an enhancing effect on permeation probably due to its protection of AVP. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.

Malaria is currently one of the most imperative parasitic diseases of the developing world. Current effective treatment options are limited because of increasing drug resistance, treatment cost effectiveness and treatment availability. Novel drug delivery systems are a new approach for increased efficacy in the treatment of the disease. Pheroid™ technology, a proven drug delivery system, in combination with anti-malarial drugs was evaluated in this study. The aim of this study was to evaluate the possible enhancement of the efficacy of the existing anti-malarial drugs in combination with Pheroid™ technology. The efficacy of existing anti-malarial drugs in combination with Pheroids was investigated in vitro with a chloroquine RB-1-resistant strain of P. falciparum. Two different Pheroid formulations, vesicles and microsponges, were used and the control medium consisted of sterile water for injection. Parasitaemia levels were determined microscopically and expressed as a percentage. An in vivo pilot study was also conducted using the P. berghei mouse model. The mice were grouped into seven batches of three mice each. The control group was treated with a Pheroid vesicle formulation only. Three of the groups were treated with three different concentrations of chloroquine dissolved in water namely 2 mg/kg; 5 mg/kg and 10 mg/kg bodyweight (bw) respectively, while the other three groups received the same three concentrations of chloroquine entrapped in Pheroid vesicle formulations. The measure of parasite growth inhibition (percentage parasitaemia), the survival rates and the percentage chemosuppresion was determined. In the in vivo study, all concentrations of chloroquine entrapped in Pheroid vesicles showed suppressed parasitaemia levels up to 11 days post infection. From day 11, the parasitaemia increases rapidly and becomes higher than that in groups treated with chloroquine in water. Chloroquine entrapped in Pheroid vesicles showed improved activity against a chloroquine resistant strain (RB-1) in vitro. The efficacy was enhanced by 1544.62%. The efficacy of mefloquine, artemether and artesunate in Pheroid microsponges were enhanced by 314.32%, 254.86% and 238.78% respectively. It can be concluded that Pheroid™ technology has potential to enhance the efficacy of anti-malaria drugs. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2008.

Local anaesthetics have been implemented extensively in the case of a variety of painful superficial procedures, venipuncture, skin graft harvesting, anal or genital pruritus, poison ivy rashes, postherpetic neuralgia and several other dermatoses. The dilemma with commercially available local acting anaesthetics is that it may take well up to an hour to produce an anaesthetic effect. Anaesthetics have to traverse the highly efficient barrier, the stratum corneum, in order to reach the intended target site which is the free nerve endings located in the dermis. The objective of this study was to compare the transdermal delivery of an eutectic combination of two ionisable amide types of local anaesthetics, lidocaine HCI and prilocaine HCI, delivered with the novel Pheroid™ technology to that of a commercially available product in order to establish whether the lag time could be significantly reduced. Several techniques of promoting the penetration of these anaesthetics have previously been employed, including occlusive dressing, entrapment in liposomes and miscelles, iontophoretic delivery and so forth. The Pheroid™ delivery system is novel technology that entails improved delivery of several active compounds. It is a submicron emulsion type formulation that possesses the ability to be transformed in morphology and size, thereby affording it tremendous flexibility. Since it primarily consists of unsaturated essential fatty acids, it is not seen as foreign to the body but rather as a skin-friendly carrier. Vertical Franz cell diffusion studies were performed over a 12 hour period using Caucasian female abdominal skin obtained, with the consent of the donor, from abdominoplastic surgery. Comparison was made between the commercial product EMLA® cream, the active local anaesthetics dissolved in phosphate buffered solution (PBS) and the active ingredients entrapped within Pheroid™ vesicles. Distinct entrapment could be ascertained visually by confocal laser scanning microscopy (CLSM). The amount of drug that traversed the epidermal membrane into the receptor phase was then assayed by high performance liquid chromatography (HPLC). The results obtained with the Pheroid™ vesicles revealed a biphasic character with rapid permeation during the first two hours, followed by a plateau between 3 to 12 hours. The initial dramatic increase in percentage yield and flux indicates that the Pheroid™ carrier enhances the transdermal delivery of the actives in order to accelerate the onset of action. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2009.

Local anaesthetics have been implemented extensively in the case of a variety of painful superficial procedures, venipuncture, skin graft harvesting, anal or genital pruritus, poison ivy rashes, postherpetic neuralgia and several other dermatoses. The dilemma with commercially available local acting anaesthetics is that it may take well up to an hour to produce an anaesthetic effect. Anaesthetics have to traverse the highly efficient barrier, the stratum corneum, in order to reach the intended target site which is the free nerve endings located in the dermis. The objective of this study was to compare the transdermal delivery of an eutectic combination of two ionisable amide types of local anaesthetics, lidocaine HCI and prilocaine HCI, delivered with the novel Pheroid™ technology to that of a commercially available product in order to establish whether the lag time could be significantly reduced. Several techniques of promoting the penetration of these anaesthetics have previously been employed, including occlusive dressing, entrapment in liposomes and miscelles, iontophoretic delivery and so forth. The Pheroid™ delivery system is novel technology that entails improved delivery of several active compounds. It is a submicron emulsion type formulation that possesses the ability to be transformed in morphology and size, thereby affording it tremendous flexibility. Since it primarily consists of unsaturated essential fatty acids, it is not seen as foreign to the body but rather as a skin-friendly carrier. Vertical Franz cell diffusion studies were performed over a 12 hour period using Caucasian female abdominal skin obtained, with the consent of the donor, from abdominoplastic surgery. Comparison was made between the commercial product EMLA® cream, the active local anaesthetics dissolved in phosphate buffered solution (PBS) and the active ingredients entrapped within Pheroid™ vesicles. Distinct entrapment could be ascertained visually by confocal laser scanning microscopy (CLSM). The amount of drug that traversed the epidermal membrane into the receptor phase was then assayed by high performance liquid chromatography (HPLC). The results obtained with the Pheroid™ vesicles revealed a biphasic character with rapid permeation during the first two hours, followed by a plateau between 3 to 12 hours. The initial dramatic increase in percentage yield and flux indicates that the Pheroid™ carrier enhances the transdermal delivery of the actives in order to accelerate the onset of action. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2009.

Malaria affects millions of people annually especially in third world countries. Increase in resistance and limited research being conducted adds to the global burden of malaria. Mefloquine, known for unwanted adverse reactions and neurotoxicity, is highly lipophilic and is still used as treatment and prophylaxis. Lipid drug delivery systems are commonly used to increase solubility and efficacy and decrease toxicity. The most generally used lipid drug delivery system is liposomes. The lipid bilayer structure varying in size from 25 nm to 100 μm can entrap both hydrophilic and lipophilic compounds. Similar in structure and size to liposomes, Pheroid™ technology consist of natural fatty acids and is also able to entrap lipophilic and hydrophilic compounds. The aim of this study was to formulate liposomes and Pheroid™ vesicles loaded with mefloquine and evaluate the physiochemical characteristic of the formulations followed by efficacy and toxicity studies. Pheroid™ vesicles and liposomes with and without mefloquine were evaluated in size, morphology, pH and entrapment efficacy during three month accelerated stability testing. Optimization of size determination by flow cytometry lead to accurate determination of size for both Pheroid™ vesicles and liposomes. During the three months stability testing, Pheroid™ vesicles showed a small change in size from 3.07 ± 0.01 μm to approximately 3 μm for all three temperatures. Confocal laser scanning microscopic evaluation of the liposomes showed structures uniform in spherical shape and size. No difference in size or structure between the Pheroid™ vesicles with and without mefloquine were obtained. Significant increase (p=0.027) in size from 6.46 ± 0.01 μm to above 10 μm was observed for liposomes at all the temperatures. Clearly formed lipid bilayer structures were observed on micrographs. With the addition of mefloquine to the liposome formulation, a decrease in the amount of bilayer structures and an increase in oil droplets were found. Entrapment efficacy was determined by firstly separating the entrapped drug from the unentrapped drug utilizing a Sephadex®G50 mini column. This was followed by spectrophotometric evaluation by UV-spectrophotometry at 283 nm. Initial entrapment efficacy of both Pheroid™ vesicles and liposomes was above 60%. An increase in entrapment efficacy was observed for Pheroid™ vesicles. The addition of mefloquine to already formulated Pheroid™ vesicles illustrated entrapment efficacy of 60.14 ± 5.59% after 14 days. Formulations loaded with mefloquine resulted in lower pH values as well as a decrease in pH over time. Optimization of efficacy studies utilizing propidium iodide was necessary due to the similarity in size and shape of the drug delivery systems to erythrocytes. A gating strategy was successfully implemented for the determination of the percentage parasitemia. Efficacy testing of mefloquine loaded in Pheroid™ vesicles and liposomes showed a 186% and 207% decrease in parasitemia levels compared to the control of mefloquine. Toxicity studies conducted include haemolysis and ROS (reactive oxygen species) analysis on erythrocytes as well as cell viability on mouse neuroblastoma cells. Pheroid™ vesicles with and without mefloquine resulted in a dose dependent increase in ROS and haemolysis over time. A dose dependent increase in ROS and haemolysis in both liposome formulations were observed, but to a lesser extent. Mefloquine proved to be neurotoxic with similar results obtained when mefloquine was entrapped in liposomes. Pheroid™ vesicles seem to have neuroprotective properties resulting in higher cell viability. Mefloquine could be entrapped successfully in Pheroid™ vesicles and less in liposomes. Pheroid™ vesicles was more stable over a three months accelerated stability testing with more favourable characteristics. The increase in ROS levels of Pheroid™ vesicles could be responsible for the higher efficacy and haemolytic activity. DL-α-Tocopherol in Pheroid™ vesicles possibly acted as a pro-oxidant due to the presence of iron in the erythrocytes. DL-α-Tocopherol showed possible antioxidant properties in the neurotoxicity evaluation resulting in higher cell viability. Even though liposomes illustrated higher efficacy and little haemolysis and ROS production, no difference in neurotoxicity was observed together with unfavourable properties during stability testing makes this drug delivery system less favourable in comparison to Pheroid™ vesicles. Mefloquine was successfully incorporated into Pheroid™ vesicles resulted in high efficacy and showed possible neuroprotection and therefore makes it an ideal system for treatment of malaria. / Thesis (Ph.D. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2011

Malaria affects millions of people annually especially in third world countries. Increase in resistance and limited research being conducted adds to the global burden of malaria. Mefloquine, known for unwanted adverse reactions and neurotoxicity, is highly lipophilic and is still used as treatment and prophylaxis. Lipid drug delivery systems are commonly used to increase solubility and efficacy and decrease toxicity. The most generally used lipid drug delivery system is liposomes. The lipid bilayer structure varying in size from 25 nm to 100 μm can entrap both hydrophilic and lipophilic compounds. Similar in structure and size to liposomes, Pheroid™ technology consist of natural fatty acids and is also able to entrap lipophilic and hydrophilic compounds. The aim of this study was to formulate liposomes and Pheroid™ vesicles loaded with mefloquine and evaluate the physiochemical characteristic of the formulations followed by efficacy and toxicity studies. Pheroid™ vesicles and liposomes with and without mefloquine were evaluated in size, morphology, pH and entrapment efficacy during three month accelerated stability testing. Optimization of size determination by flow cytometry lead to accurate determination of size for both Pheroid™ vesicles and liposomes. During the three months stability testing, Pheroid™ vesicles showed a small change in size from 3.07 ± 0.01 μm to approximately 3 μm for all three temperatures. Confocal laser scanning microscopic evaluation of the liposomes showed structures uniform in spherical shape and size. No difference in size or structure between the Pheroid™ vesicles with and without mefloquine were obtained. Significant increase (p=0.027) in size from 6.46 ± 0.01 μm to above 10 μm was observed for liposomes at all the temperatures. Clearly formed lipid bilayer structures were observed on micrographs. With the addition of mefloquine to the liposome formulation, a decrease in the amount of bilayer structures and an increase in oil droplets were found. Entrapment efficacy was determined by firstly separating the entrapped drug from the unentrapped drug utilizing a Sephadex®G50 mini column. This was followed by spectrophotometric evaluation by UV-spectrophotometry at 283 nm. Initial entrapment efficacy of both Pheroid™ vesicles and liposomes was above 60%. An increase in entrapment efficacy was observed for Pheroid™ vesicles. The addition of mefloquine to already formulated Pheroid™ vesicles illustrated entrapment efficacy of 60.14 ± 5.59% after 14 days. Formulations loaded with mefloquine resulted in lower pH values as well as a decrease in pH over time. Optimization of efficacy studies utilizing propidium iodide was necessary due to the similarity in size and shape of the drug delivery systems to erythrocytes. A gating strategy was successfully implemented for the determination of the percentage parasitemia. Efficacy testing of mefloquine loaded in Pheroid™ vesicles and liposomes showed a 186% and 207% decrease in parasitemia levels compared to the control of mefloquine. Toxicity studies conducted include haemolysis and ROS (reactive oxygen species) analysis on erythrocytes as well as cell viability on mouse neuroblastoma cells. Pheroid™ vesicles with and without mefloquine resulted in a dose dependent increase in ROS and haemolysis over time. A dose dependent increase in ROS and haemolysis in both liposome formulations were observed, but to a lesser extent. Mefloquine proved to be neurotoxic with similar results obtained when mefloquine was entrapped in liposomes. Pheroid™ vesicles seem to have neuroprotective properties resulting in higher cell viability. Mefloquine could be entrapped successfully in Pheroid™ vesicles and less in liposomes. Pheroid™ vesicles was more stable over a three months accelerated stability testing with more favourable characteristics. The increase in ROS levels of Pheroid™ vesicles could be responsible for the higher efficacy and haemolytic activity. DL-α-Tocopherol in Pheroid™ vesicles possibly acted as a pro-oxidant due to the presence of iron in the erythrocytes. DL-α-Tocopherol showed possible antioxidant properties in the neurotoxicity evaluation resulting in higher cell viability. Even though liposomes illustrated higher efficacy and little haemolysis and ROS production, no difference in neurotoxicity was observed together with unfavourable properties during stability testing makes this drug delivery system less favourable in comparison to Pheroid™ vesicles. Mefloquine was successfully incorporated into Pheroid™ vesicles resulted in high efficacy and showed possible neuroprotection and therefore makes it an ideal system for treatment of malaria. / Thesis (Ph.D. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2011

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.