Active pharmaceutical ingredients (APIs), which are incorporated in different formulations, i.e. creams, gels, foams, etc., are applied to the skin for a therapeutic effect. This therapeutic effect could either be required in the top layer of the skin (topical drug delivery) or deeper layers to reach the blood capillaries (transdermal drug delivery). Transdermal delivery avoids oral administration route limitations, such as first pass metabolism which is the rapid clearance of the drug in the gastrointestinal tract and degradation by enzymes. This delivery targets the drugs to skin sites, where there are significant advantages which include: improved patient compliance, a steady drug delivery state, less frequent dosing, adverse effects are minimal, it is less invasive and issues with the gastrointestinal absorption are avoided by eliminating the first pass metabolism (Perrie et al., 2012:392). This type of delivery is not free from limitations even though the skin can be employed for targeted drug delivery and is a readily available and large accessible surface area for adsorption of drugs. The most upper layer of the human skin, the stratum corneum, which is a watertight barrier, offers defence against hazardous exterior materials such as fungi, allergens, viruses and other molecules. This indicates the stratum corneum controls the drug penetration of most drugs to permeate the skin barrier (Lam & Gambari, 2014:27). Pravastatin is hydrophilic and is a 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitor which inhibits cholesterol synthesis, a rate-limiting step, in the liver, thus decreasing the level of plasma low density lipoprotein cholesterol (LDL-C) (Heath et al., 1998:42). It can also slow the progression of atherosclerosis and can lower the incident of coronary events (Haria & McTavish, 1997:299). The first aim of the study is to deliver pravastatin transdermally into the blood circulation. Currently, pravastatin is only administered in oral dosages and can cause highly negative adverse effects such as myopathy and increased liver enzymes. This increase in liver enzymes causes hepatotoxicity and therefore would be ideal if pravastatin could be delivered transdermally, as the first pass metabolic effect would be nullified and adverse effects would decrease drastically (Gadi et al., 2013:648). Prof JW Wiechers‟ Delivery Gap Principle was designed in attempt to effectively enhance transdermal drug delivery. This Delivery Gap Principle was incorporated in the computer programme he developed known as “Formulating for Efficacy” (FFE™). The transdermal delivery of suggested APIs, which in this case is pravastatin, when incorporated into a formulation, may be optimised transdermally. The FFE™ computer programme suggests that the oil phase can be optimised, which in turn leads to better permeation through the skin to the target site (transdermal). The formula can be manipulated to reach desired polarity. The second aim of this in vitro study was to investigate the implementation of Wiechers‟ Delivery Gap Principle in a semi-solid dosage form, for the transdermal delivery of pravastatin sodium (2%). Six formulations, of which three were cream and three were emulgel formulations incorporated with pravastatin sodium (2%), were formulated. Each formulation had a different polarity, i.e. hydrophilic cream (HC) and emulgel (HE), lipophilic cream (LC) and emulgel (LE) and optimised cream (OC) and emulgel (OE). A high performance liquid chromatography (HPLC) method was developed and validated to analyse the concentration of pravastatin. Both the octanol-buffer distribution coefficient (log D) and the aqueous solubility of pravastatin were determined. For the API to permeate through the skin into the blood circulation, certain physicochemical properties are important and according to Naik et al (2000:321), there are specific ideal limits for the API in the formulations which include log D (1 to 3) and a aqueous solubility of >1 mg/ml. The aqueous solubility of 197.5 mg/ml in phosphate buffer solution (PBS) (pH 7.4) at a temperature of 32 °C indicated penetration was favourable (Naik et al., 2000:321), whilst the log D value of -0.703 indicated the API was unfavourable for skin penetration (Naik et al., 2000:321). Membrane release studies were conducted using a synthetic membrane to determine whether pravastatin was released from the six formulations each containing 2% pravastatin prior to diffusion studies with. The OE yielded the highest median flux value (7.175 μg/cm2.h), followed the by LE (6.401 μg/cm2.h), HE (6.355 μg/cm2.h), HC (5.061 μg/cm2.h), OC (4.297 μg/cm2.h) and lastly, LC (3.115 μg/cm2.h). By looking at the aforementioned data values, it was concluded that the emulgels performed better than the cream formulations when median flux values were compared. By using dermatomed excised female Caucasian skin, an execution of Franz cell diffusion studies were performed over a period of 12 h, followed by a tape-stripping experiment to determine which semi-solid formulation delivered pravastatin best on the skin and the results of the different polarity formulations were compared. The median amount per area which permeated through the skin after 12 h was as follows: the OE formulation (2.578 μg/cm2) depicted the highest median amount per area, followed by OC (1.449 μg/cm2), HC (0.434 μg/cm2), LE (0.121 μg/cm2), HE (0.055 μg/cm2) and lastly LC (0.000 μg/cm2). These results validate Wiechers` theory that when the oil phase is optimised, with regard to the same polarity as the skin, permeation will be enhanced (Wiechers, 2011). During both the membrane studies and the skin diffusion studies it was evident the emulgel formulations performed better and pravastatin permeated better than the cream formulations. When skin diffusion and membrane median data values were compared, it was evident in both the membrane release studies and the skin diffusion studies that OE yielded the highest median values and LC the lowest median values. It was clear that all six different formulations released pravastatin, but LC displayed no permeation into the systemic circulation (receptor phase). The data of the different polarity formulations which yielded the best results with regards to median concentrations within the stratum corneum-epidermis and epidermis-dermis, were identified and are: within the stratum corneum-epidermis, HE (1.448 μg/ml) yielded the highest median concentration pravastatin, followed by LE (1.301 μg/ml), LC (0.676 μg/ml), HC (0.505 μg/ml), OE (0.505 μg/ml) and lastly OC (0.400 μg/ml). As emulgels (hydrophilic) contain more water than creams (lipophilic), the penetration enhancement effect can be explained by hydration, since the water hydrated the skin leading the lipids to open and the stratum corneum to swell (Williams & Barry, 2004:606). Therefore more API could permeate into the skin. Within the epidermis-dermis the highest median concentration median was yielded by OE (0.849 μg/ml), followed by LC (0.572 μg/ml), HC (0.524 μg/ml), OC (0.355 μg/ml), HE (0.309 μg/ml) and lastly LE (0.138 μg/ml). Different polarity formulations permeating the viable epidermis could be a result of the solubility characteristics of the formulations. It contained both lipid properties (formulations contained oil content), leading to permeation through the stratum corneum and aqueous properties, which lead to diffusion into the underlying layers of the epidermis (Perrie et al., 2012:392). According to Perrie (2012:392), formulations that need to be delivered transdermally, must permeate through the lipophilic stratum corneum and thereafter the hydrophilic dermal layers to reach the blood circulation, which means formulations must consist of both lipophilic and aqueous solubility properties. When comparing the stratum corneum-epidermis (lipophilic) with the epidermis-dermis (more hydrophilic) and receptor phase (hydrophilic; systemic circulation), it is evident that all formulations had lipophilic and hydrophilic properties, as the API permeated through the stratum corneum and penetrated the deeper layers of the skin (viable epidermis) When all polarity formulations were compared, i.e. optimised, hydrophilic and lipophilic, it was observed that the optimised formulations depicted the highest median concentration values in the receptor phase (skin diffusion), but lowest median concentration in stratum corneum-epidermis, therefore the optimised formulation permeated best through the stratum corneum-epidermis. The reason for this could be that the optimised formulations had the same polarity as the skin (17, 8, 8), thus permeating through the skin to the receptor fluid more efficiently (Wiechers, 2011). It was observed that LC penetrated both stratum corneum-epidermis and epidermis-dermis, but did not permeate through the skin to the receptor fluid (systemic circulation), making it a good delivery vehicle for topical delivery. Overall when the emulgel and cream formulations are compared, according to their ability to deliver pravastatin transdermally, it is evident the pravastatin diffused more from the emulgel formulations than the cream formulations. This could be due to the fact that emulgels are more hydrophilic as they contain more water, resulting in the emulgels diffusing to the deeper layers of the skin (more hydrophilic viable epidermis) (Benson, 2005:28). All formulations contained not only aqueous (hydrophilic) but also lipid (lipophilic) solubility properties, therefore making it lipophilic enough to permeate the stratum corneum and hydrophilic enough to penetrate to deeper skin layers (viable epidermis) (Perrie et al., 2012:392). All formulations could still permeate the viable epidermis despite different polarities being used and all were appropriate candidates, although some were more suitable than others. The understanding from this study is that: * pravastatin could be delivered topically by all formulations, * the best formulation to reach the systemic formulation is the optimised emulgel, * the best formulation to deliver pravastatin topically is the hydrophilic emulgel. / MSc (Pharmaceutics), North-West University, Potchefstroom Campus, 2015

Active pharmaceutical ingredients (APIs), which are incorporated in different formulations, i.e. creams, gels, foams, etc., are applied to the skin for a therapeutic effect. This therapeutic effect could either be required in the top layer of the skin (topical drug delivery) or deeper layers to reach the blood capillaries (transdermal drug delivery). Transdermal delivery avoids oral administration route limitations, such as first pass metabolism which is the rapid clearance of the drug in the gastrointestinal tract and degradation by enzymes. This delivery targets the drugs to skin sites, where there are significant advantages which include: improved patient compliance, a steady drug delivery state, less frequent dosing, adverse effects are minimal, it is less invasive and issues with the gastrointestinal absorption are avoided by eliminating the first pass metabolism (Perrie et al., 2012:392). This type of delivery is not free from limitations even though the skin can be employed for targeted drug delivery and is a readily available and large accessible surface area for adsorption of drugs. The most upper layer of the human skin, the stratum corneum, which is a watertight barrier, offers defence against hazardous exterior materials such as fungi, allergens, viruses and other molecules. This indicates the stratum corneum controls the drug penetration of most drugs to permeate the skin barrier (Lam & Gambari, 2014:27). Pravastatin is hydrophilic and is a 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitor which inhibits cholesterol synthesis, a rate-limiting step, in the liver, thus decreasing the level of plasma low density lipoprotein cholesterol (LDL-C) (Heath et al., 1998:42). It can also slow the progression of atherosclerosis and can lower the incident of coronary events (Haria & McTavish, 1997:299). The first aim of the study is to deliver pravastatin transdermally into the blood circulation. Currently, pravastatin is only administered in oral dosages and can cause highly negative adverse effects such as myopathy and increased liver enzymes. This increase in liver enzymes causes hepatotoxicity and therefore would be ideal if pravastatin could be delivered transdermally, as the first pass metabolic effect would be nullified and adverse effects would decrease drastically (Gadi et al., 2013:648). Prof JW Wiechers‟ Delivery Gap Principle was designed in attempt to effectively enhance transdermal drug delivery. This Delivery Gap Principle was incorporated in the computer programme he developed known as “Formulating for Efficacy” (FFE™). The transdermal delivery of suggested APIs, which in this case is pravastatin, when incorporated into a formulation, may be optimised transdermally. The FFE™ computer programme suggests that the oil phase can be optimised, which in turn leads to better permeation through the skin to the target site (transdermal). The formula can be manipulated to reach desired polarity. The second aim of this in vitro study was to investigate the implementation of Wiechers‟ Delivery Gap Principle in a semi-solid dosage form, for the transdermal delivery of pravastatin sodium (2%). Six formulations, of which three were cream and three were emulgel formulations incorporated with pravastatin sodium (2%), were formulated. Each formulation had a different polarity, i.e. hydrophilic cream (HC) and emulgel (HE), lipophilic cream (LC) and emulgel (LE) and optimised cream (OC) and emulgel (OE). A high performance liquid chromatography (HPLC) method was developed and validated to analyse the concentration of pravastatin. Both the octanol-buffer distribution coefficient (log D) and the aqueous solubility of pravastatin were determined. For the API to permeate through the skin into the blood circulation, certain physicochemical properties are important and according to Naik et al (2000:321), there are specific ideal limits for the API in the formulations which include log D (1 to 3) and a aqueous solubility of >1 mg/ml. The aqueous solubility of 197.5 mg/ml in phosphate buffer solution (PBS) (pH 7.4) at a temperature of 32 °C indicated penetration was favourable (Naik et al., 2000:321), whilst the log D value of -0.703 indicated the API was unfavourable for skin penetration (Naik et al., 2000:321). Membrane release studies were conducted using a synthetic membrane to determine whether pravastatin was released from the six formulations each containing 2% pravastatin prior to diffusion studies with. The OE yielded the highest median flux value (7.175 μg/cm2.h), followed the by LE (6.401 μg/cm2.h), HE (6.355 μg/cm2.h), HC (5.061 μg/cm2.h), OC (4.297 μg/cm2.h) and lastly, LC (3.115 μg/cm2.h). By looking at the aforementioned data values, it was concluded that the emulgels performed better than the cream formulations when median flux values were compared. By using dermatomed excised female Caucasian skin, an execution of Franz cell diffusion studies were performed over a period of 12 h, followed by a tape-stripping experiment to determine which semi-solid formulation delivered pravastatin best on the skin and the results of the different polarity formulations were compared. The median amount per area which permeated through the skin after 12 h was as follows: the OE formulation (2.578 μg/cm2) depicted the highest median amount per area, followed by OC (1.449 μg/cm2), HC (0.434 μg/cm2), LE (0.121 μg/cm2), HE (0.055 μg/cm2) and lastly LC (0.000 μg/cm2). These results validate Wiechers` theory that when the oil phase is optimised, with regard to the same polarity as the skin, permeation will be enhanced (Wiechers, 2011). During both the membrane studies and the skin diffusion studies it was evident the emulgel formulations performed better and pravastatin permeated better than the cream formulations. When skin diffusion and membrane median data values were compared, it was evident in both the membrane release studies and the skin diffusion studies that OE yielded the highest median values and LC the lowest median values. It was clear that all six different formulations released pravastatin, but LC displayed no permeation into the systemic circulation (receptor phase). The data of the different polarity formulations which yielded the best results with regards to median concentrations within the stratum corneum-epidermis and epidermis-dermis, were identified and are: within the stratum corneum-epidermis, HE (1.448 μg/ml) yielded the highest median concentration pravastatin, followed by LE (1.301 μg/ml), LC (0.676 μg/ml), HC (0.505 μg/ml), OE (0.505 μg/ml) and lastly OC (0.400 μg/ml). As emulgels (hydrophilic) contain more water than creams (lipophilic), the penetration enhancement effect can be explained by hydration, since the water hydrated the skin leading the lipids to open and the stratum corneum to swell (Williams & Barry, 2004:606). Therefore more API could permeate into the skin. Within the epidermis-dermis the highest median concentration median was yielded by OE (0.849 μg/ml), followed by LC (0.572 μg/ml), HC (0.524 μg/ml), OC (0.355 μg/ml), HE (0.309 μg/ml) and lastly LE (0.138 μg/ml). Different polarity formulations permeating the viable epidermis could be a result of the solubility characteristics of the formulations. It contained both lipid properties (formulations contained oil content), leading to permeation through the stratum corneum and aqueous properties, which lead to diffusion into the underlying layers of the epidermis (Perrie et al., 2012:392). According to Perrie (2012:392), formulations that need to be delivered transdermally, must permeate through the lipophilic stratum corneum and thereafter the hydrophilic dermal layers to reach the blood circulation, which means formulations must consist of both lipophilic and aqueous solubility properties. When comparing the stratum corneum-epidermis (lipophilic) with the epidermis-dermis (more hydrophilic) and receptor phase (hydrophilic; systemic circulation), it is evident that all formulations had lipophilic and hydrophilic properties, as the API permeated through the stratum corneum and penetrated the deeper layers of the skin (viable epidermis) When all polarity formulations were compared, i.e. optimised, hydrophilic and lipophilic, it was observed that the optimised formulations depicted the highest median concentration values in the receptor phase (skin diffusion), but lowest median concentration in stratum corneum-epidermis, therefore the optimised formulation permeated best through the stratum corneum-epidermis. The reason for this could be that the optimised formulations had the same polarity as the skin (17, 8, 8), thus permeating through the skin to the receptor fluid more efficiently (Wiechers, 2011). It was observed that LC penetrated both stratum corneum-epidermis and epidermis-dermis, but did not permeate through the skin to the receptor fluid (systemic circulation), making it a good delivery vehicle for topical delivery. Overall when the emulgel and cream formulations are compared, according to their ability to deliver pravastatin transdermally, it is evident the pravastatin diffused more from the emulgel formulations than the cream formulations. This could be due to the fact that emulgels are more hydrophilic as they contain more water, resulting in the emulgels diffusing to the deeper layers of the skin (more hydrophilic viable epidermis) (Benson, 2005:28). All formulations contained not only aqueous (hydrophilic) but also lipid (lipophilic) solubility properties, therefore making it lipophilic enough to permeate the stratum corneum and hydrophilic enough to penetrate to deeper skin layers (viable epidermis) (Perrie et al., 2012:392). All formulations could still permeate the viable epidermis despite different polarities being used and all were appropriate candidates, although some were more suitable than others. The understanding from this study is that: * pravastatin could be delivered topically by all formulations, * the best formulation to reach the systemic formulation is the optimised emulgel, * the best formulation to deliver pravastatin topically is the hydrophilic emulgel. / MSc (Pharmaceutics), North-West University, Potchefstroom Campus, 2015

Objective: The aim of this study was to investigate inherent in vitro permeability, metabolism, and cytotoxicity of idebenone - an active used to protect skin as an anti-aging agent -and compare it to idebenone linoleate. Methods: Idebenone and idebenone linoleate were investigated in pig ear skin and melanoma (B16: F10 mouse) cells. Diffusion experiments were conducted at 37 °C (bath temperature) using Franz diffusion cells. Authentic metabolite samples were synthetically prepared. Samples were analyzed using liquid chromatography-mass spectrometry/mass spectrometry. Cell viability was determined via the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay. Results: Idebenone was shown to permeate across viable porcine ear tissue; there was no evidence that idebenone linoleate permeated across porcine ear tissue after 4 h. Idebenone was metabolized to idebenone acid in both pig ear and mouse melanocytes; only minor idebenone linoleate metabolism was observed. Idebenone displayed delayed in vitro toxicity (via MTT assay) in melanocytes, while idebenone linoleate displayed no such in vitro toxicity. Conclusions: The in vitro metabolism and cytotoxicity results suggest that metabolic activation of idebenone is the likely culprit that activates the skin irritation mechanism via idebenone in vivo usage. An idebenone ester (e.g. idebenone linoleate) appears to provide a superior in vitro safety profile over idebenone.

Culture involves the handing down of information, traditions, knowledge and skill, views and ideals from one individual to another and across generations by means of social transmission expressed in manufactured objects and behaviour. The evolution of cumulative culture, a human specific capacity, makes possible an inheritance system that is governed by the same Darwinian principles as biological evolution. Cumulative culture has made possible the build-up or ratcheting effect of knowledge and traditions that when put together allow for advanced technology, medicine, education and other highly advanced cognitive processes that characterise humans from non human animals. This dissertation dedicates the first chapter to review the literature pertaining to this topic; describing various types of social learning processes and methodological approaches that are used to query and broadly describe the process of culture in various animals. The following two chapters (2 and 3) present three experiments that provide methodical and systematic exploration of the social transmission process which occurs in chimpanzees; using 3 artificial foraging devices, the 3 studies systematically demonstrate that chimpanzees have the capacity to transmit culture from one individual to another and serially across neighbouring communities- providing laboratory evidence of behavioural variation analogous to that observed in the wild. Chapter 4 then goes on to describe an experiment that tests a number of hypothesised biases in cultural transmission. Looking specifically at social dynamics at play during the transmission of skill within ape groups - I systematically analyse the effects of directed social learning; focusing on kin and status based strategies that are characteristic of group living apes. Chapter 5 is an original, empirical and methodically comparative analysis of hierarchically organized behaviour in human children and chimpanzees using a hierarchically organized artificial fruit. The final chapter (6) discusses the findings of each of the five experiments and compares the results to findings at other captive and wild research sites. I then broaden the topic to explore how the findings relate to broad issues in literature and provide a framework for future research and for understanding the complex mechanisms of intelligent systems.