The aim of this study was to investigate the effect of different penetration enhancers containing essential fatty acids (EFAs) on the transdermal delivery of flurbiprofen. Flurbiprofen was used as a marker / model compound. Fatty acids were chosen as penetration enhancers for their ability to reversibly increase skin permeability through entering the lipid bilayers and disrupting their ordered domains. Fatty acids are natural, non-toxic compounds (Karande & Mitragotri, 2009:2364). Evening primrose oil, vitamin F and Pheroid™ technology all contain fatty acids and were compared using a cream based-formulation. This selection was to ascertain whether EFAs exclusively, or EFAs in a delivery system, would have a significant increase in the transdermal delivery of a compound. For an active pharmaceutical ingredient (API) to be effectively delivered transdermally, it has to be soluble in lipophilic, as well as hydrophilic mediums (Naik et al., 2000:319; Swart et al., 2005:72). This is due to the intricate structure of the skin, where the stratum corneum (outermost layer) is the primary barrier, which regulates skin transport (Barry, 2001:102; Moser et al., 2001:103; Venus et al., 2010:469). Flurbiprofen is highly lipophilic (log P = 4.24) with poor aqueous solubility. It has a molecular weight lower than 500 g/mol indicating that skin permeation may be possible, though the high log P indicates that some difficulty is to be expected (Dollery, 1999:F126; Hadgraft, 2004:292; Swart et al., 2005:72; Karande & Mitragotri, 2009:2363; Drugbank, 2012). In vitro transdermal diffusion studies (utilising vertical Franz diffusion cells) were conducted, using donated abdominal skin from Caucasian females. The studies were conducted over 12 h with extractions of the receptor phase every 2 h to ensure sink conditions. Prior to skin diffusion studies, membrane release studies were performed to determine whether the API was released from the formulation. Membrane release studies were conducted over 6 h and extractions done hourly. Tape stripping experiments were performed on the skin circles after 12 h diffusion studies to determine the concentration flurbiprofen present in the stratum corneum and dermisepidermis. The flurbiprofen concentrations present in the samples were determined using high performance chromatography and a validated method. Membrane release results indicated the following rank order for flurbiprofen from the different formulations: vitamin F > control > evening primrose oil (EPO) >> Pheroid™. The control formulation contained only flurbiprofen and no penetration enhancers. Skin diffusion results on the other hand, indicated that flurbiprofen was present in the stratum corneum and the dermisepidermis. The concentration flurbiprofen present in the receptor phase of the Franz cells (representing human blood) followed the subsequent rank order: EPO > control > vitamin F >> Pheroid™. All the formulations stipulated a lag time shorter than that of the control formulation (1.74 h), with the EPO formulation depicting the shortest (1.36 h). The control formulation presented the highest flux (8.41 μg/cm2.h), with the EPO formulation following the closest (8.12 μg/cm2.h). It could thus be concluded that fatty acids exclusively, rather than in a delivery system, had a significant increase in the transdermal delivery of flurbiprofen. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

Background: Dietary fat intake particularly of omega-3 and omega-6 fatty acids play an important role in growth and development and influence the risk of nutrition related non communicable diseases. These dietary intakes are reflected in the red blood cell (RBC) fatty acid profile. Aim: The aim of this study was to assess the fatty acid profile (%) of red blood cell membrane phospholipids in relation to the dietary intake of South African children aged 2 to 5 years, and of their mothers/caregivers from three communities, each with distinct dietary patterns. Method: In this cross-sectional observational study, approximately 105 children, aged: 2-5 years and their mother/caregivers were selected from three different geographical areas. These included; the urban community of De Aar (n=105), the urban coastal community Ocean View (n=93) and the rural community of Sekhukhune District (n=104). The red blood cell membrane total phospholipid fatty acid profile was determined by gas chromatography. A 24-hour dietary recall was done for each child and mother/caregiver as well as a socio-demographic questionnaire answered by each mother/caregiver. The mean and standard deviations of the RBC fatty acids were determined and compared through an analysis of variance (ANOVA) test followed by a Bonferroni post hoc test. Age and gender were controlled for in the children and age was controlled for in the mothers/caregivers. The median dietary intake (quartile range) was compared between communities by a Kruskal-Wallis test. The relationship between RBC membrane total phospholipid fatty acid profile and dietary fatty acid intake was done by stratifying the data for the three groups combined into tertiles according to RBC fatty acid profile and comparing the median (quartile range) of the dietary fatty acid intake in the different strata. Results: In the children, the total dietary fat, SFA and PUFA and omega-3 intake of De Aar (34.2%, 11.9%, 5.9% and 0.2% of energy, respectively) and Ocean View (33.0%, 11.2%, 7.4% and 0.2% of energy, respectively) was significantly different to Sekhukhune (19.9%, 6.5%, 3.0% and 0.1% of energy, respectively). Eicosaipentanoic (EPA) and docosahexaenoic (DHA) and α-linolenic acid (ALA) mean intake in children in all three sites was lower than recommended. In children from De Aar the RBC membrane total phospholipids contained significantly higher SFA and trans-fat percentages, while children in Sekhukhune District had significantly higher PUFA, omega-6 and omega-3 percentages. The linoleic acid (LA) profile in children from Ocean View was significantly higher than in those from De Aar and Sekhukhune District. The mother/caregivers’ dietary fat intake of total fat, SFA, PUFA and trans-fat was significantly higher in De Aar (31.7%, 10.5%, 6.3% and 0.2% of energy respectively) and Ocean View (37.4%, 12.1%, 8.5% and 0.59% of energy respectively) in comparison to Sekhukhune District (15.7%, 3.0%, 3.2% and 0.02% energy respectively). PUFA intakes were significantly higher in Ocean View (8.5% of energy). EPA, DHA and ALA dietary intakes were lower than recommended. The mother/caregiver’s RBC membrane total phospholipid SFA percentage was significantly higher in mothers/caregivers from De Aar and Ocean View whereas those from Sekhukhune District had significantly higher PUFA and omega-3 percentage. Conclusion: Differences particularly between the urban areas of De Aar and Ocean View and the rural area of Sekhukhune District were observed in dietary fat intake which was reflected in the red blood cell membrane total phospholipid fatty acid profile for children and mother/caregivers. Dietary omega-3 fatty acid intake was low in both children and mother/caregivers from all three study sites and is of concern. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2014

The aim of this study was to investigate the effect of different penetration enhancers containing essential fatty acids (EFAs) on the transdermal delivery of flurbiprofen. Flurbiprofen was used as a marker / model compound. Fatty acids were chosen as penetration enhancers for their ability to reversibly increase skin permeability through entering the lipid bilayers and disrupting their ordered domains. Fatty acids are natural, non-toxic compounds (Karande & Mitragotri, 2009:2364). Evening primrose oil, vitamin F and Pheroid™ technology all contain fatty acids and were compared using a cream based-formulation. This selection was to ascertain whether EFAs exclusively, or EFAs in a delivery system, would have a significant increase in the transdermal delivery of a compound. For an active pharmaceutical ingredient (API) to be effectively delivered transdermally, it has to be soluble in lipophilic, as well as hydrophilic mediums (Naik et al., 2000:319; Swart et al., 2005:72). This is due to the intricate structure of the skin, where the stratum corneum (outermost layer) is the primary barrier, which regulates skin transport (Barry, 2001:102; Moser et al., 2001:103; Venus et al., 2010:469). Flurbiprofen is highly lipophilic (log P = 4.24) with poor aqueous solubility. It has a molecular weight lower than 500 g/mol indicating that skin permeation may be possible, though the high log P indicates that some difficulty is to be expected (Dollery, 1999:F126; Hadgraft, 2004:292; Swart et al., 2005:72; Karande & Mitragotri, 2009:2363; Drugbank, 2012). In vitro transdermal diffusion studies (utilising vertical Franz diffusion cells) were conducted, using donated abdominal skin from Caucasian females. The studies were conducted over 12 h with extractions of the receptor phase every 2 h to ensure sink conditions. Prior to skin diffusion studies, membrane release studies were performed to determine whether the API was released from the formulation. Membrane release studies were conducted over 6 h and extractions done hourly. Tape stripping experiments were performed on the skin circles after 12 h diffusion studies to determine the concentration flurbiprofen present in the stratum corneum and dermisepidermis. The flurbiprofen concentrations present in the samples were determined using high performance chromatography and a validated method. Membrane release results indicated the following rank order for flurbiprofen from the different formulations: vitamin F > control > evening primrose oil (EPO) >> Pheroid™. The control formulation contained only flurbiprofen and no penetration enhancers. Skin diffusion results on the other hand, indicated that flurbiprofen was present in the stratum corneum and the dermisepidermis. The concentration flurbiprofen present in the receptor phase of the Franz cells (representing human blood) followed the subsequent rank order: EPO > control > vitamin F >> Pheroid™. All the formulations stipulated a lag time shorter than that of the control formulation (1.74 h), with the EPO formulation depicting the shortest (1.36 h). The control formulation presented the highest flux (8.41 μg/cm2.h), with the EPO formulation following the closest (8.12 μg/cm2.h). It could thus be concluded that fatty acids exclusively, rather than in a delivery system, had a significant increase in the transdermal delivery of flurbiprofen. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

Background: Dietary fat intake particularly of omega-3 and omega-6 fatty acids play an important role in growth and development and influence the risk of nutrition related non communicable diseases. These dietary intakes are reflected in the red blood cell (RBC) fatty acid profile. Aim: The aim of this study was to assess the fatty acid profile (%) of red blood cell membrane phospholipids in relation to the dietary intake of South African children aged 2 to 5 years, and of their mothers/caregivers from three communities, each with distinct dietary patterns. Method: In this cross-sectional observational study, approximately 105 children, aged: 2-5 years and their mother/caregivers were selected from three different geographical areas. These included; the urban community of De Aar (n=105), the urban coastal community Ocean View (n=93) and the rural community of Sekhukhune District (n=104). The red blood cell membrane total phospholipid fatty acid profile was determined by gas chromatography. A 24-hour dietary recall was done for each child and mother/caregiver as well as a socio-demographic questionnaire answered by each mother/caregiver. The mean and standard deviations of the RBC fatty acids were determined and compared through an analysis of variance (ANOVA) test followed by a Bonferroni post hoc test. Age and gender were controlled for in the children and age was controlled for in the mothers/caregivers. The median dietary intake (quartile range) was compared between communities by a Kruskal-Wallis test. The relationship between RBC membrane total phospholipid fatty acid profile and dietary fatty acid intake was done by stratifying the data for the three groups combined into tertiles according to RBC fatty acid profile and comparing the median (quartile range) of the dietary fatty acid intake in the different strata. Results: In the children, the total dietary fat, SFA and PUFA and omega-3 intake of De Aar (34.2%, 11.9%, 5.9% and 0.2% of energy, respectively) and Ocean View (33.0%, 11.2%, 7.4% and 0.2% of energy, respectively) was significantly different to Sekhukhune (19.9%, 6.5%, 3.0% and 0.1% of energy, respectively). Eicosaipentanoic (EPA) and docosahexaenoic (DHA) and α-linolenic acid (ALA) mean intake in children in all three sites was lower than recommended. In children from De Aar the RBC membrane total phospholipids contained significantly higher SFA and trans-fat percentages, while children in Sekhukhune District had significantly higher PUFA, omega-6 and omega-3 percentages. The linoleic acid (LA) profile in children from Ocean View was significantly higher than in those from De Aar and Sekhukhune District. The mother/caregivers’ dietary fat intake of total fat, SFA, PUFA and trans-fat was significantly higher in De Aar (31.7%, 10.5%, 6.3% and 0.2% of energy respectively) and Ocean View (37.4%, 12.1%, 8.5% and 0.59% of energy respectively) in comparison to Sekhukhune District (15.7%, 3.0%, 3.2% and 0.02% energy respectively). PUFA intakes were significantly higher in Ocean View (8.5% of energy). EPA, DHA and ALA dietary intakes were lower than recommended. The mother/caregiver’s RBC membrane total phospholipid SFA percentage was significantly higher in mothers/caregivers from De Aar and Ocean View whereas those from Sekhukhune District had significantly higher PUFA and omega-3 percentage. Conclusion: Differences particularly between the urban areas of De Aar and Ocean View and the rural area of Sekhukhune District were observed in dietary fat intake which was reflected in the red blood cell membrane total phospholipid fatty acid profile for children and mother/caregivers. Dietary omega-3 fatty acid intake was low in both children and mother/caregivers from all three study sites and is of concern. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2014

In pharmaceutical sciences, topical delivery is a transport process of an active pharmaceutical ingredient (API) from a formulated dosage form to the target site of action. For most topical delivery systems, the skin surface, or the specific skin layers, such as the outermost layer of the stratum corneum, the lipids amid the corneocytes within the stratum corneum, the corneocytes themselves, the epidermis, dermis, Langerhans cells, Merckle cells or the appendageal structures can be the target delivery location. When an API is delivered to the skin, it has to firstly diffuse from the formulation in which it is applied, to the skin surface. From there the API may partition into the stratum corneum, permeate across the stratum corneum and partition into the viable epidermis, from where it may partition further into the dermis and permeate across the dermis into the bloodstream (Wiechers, 2008:1-3, 7). With respect to the barrier function of the skin, the intercellular spaces within the stratum corneum contain lipids and its main purpose is to operate as a barrier to water-loss and to provide an imperative diffusional barrier to the absorption of APIs. This resistance is comprised of a complex interaction of lipids that creates a hydrophilic and lipophilic penetration pathway. The fundamental aspect underlying the impermeability of the skin, therefore, is the lipophilic nature of the stratum corneum (Bouwstra et al., 2003:4; Franz & Lehman, 2000:25; Walker & Smith, 1996:296). A common approach for the promotion of poorly penetrating APIs in transdermal delivery is the incorporation of chemical penetration enhancers in delivery systems, in order to promote the partitioning of an API into the stratum corneum. These chemicals are also referred to as accelerants, promoters and absorption promoters. Penetration enhancers are added to topical formulations and usually also partition into the stratum corneum, where they temporarily and reversibly disrupt its fundamental diffusional barrier properties, hence facilitating the absorption of an API through the skin (Büyüktimkin et al., 1997:358-359; Sinha & Kaur, 2000:1131; Walker & Smith, 1996:296). The mechanisms for the enhancement of diffusion of the API should therefore increase the solubility and partitioning of the drug from the formulation into the skin. It should further increase the solubility of the API within the skin and promote its permeability and diffusion coefficient (Rajadhyaksha et al., 1997:489). Fatty acids are recognised to effectively enhance the penetration of transdermally delivered hydrophilic and lipophilic APIs. Many penetration enhancers contain saturated and unsaturated hydrocarbon chains, and a popular fatty acid that has been used in this regard is oleic acid (Williams & Barry, 2004:609-610). It is believed that fatty acids disrupt the lipid organisation of the intercellular lipids within the stratum corneum to cause fluidisation of these bilayers, making the stratum corneum more permeable to APIs. Excipients with polar (hydrophilic) head groups and long hydrophobic chains i.e. fatty acids, can penetrate into the intercellular lipids of the stratum corneum and disrupt these endogenous lipid components, thereby increasing diffusion of an API within the skin (Barry, 2006:9-10; Hadgraft & Finnin, 2006:367-368; Kanikkannan et al., 2006:18; Williams & Barry, 2004:610). Natural oils are widely used in topical formulations and were an obvious choice in this study. Oils are liquids at room temperature, whereas fats are in solid form. They are relatively easy to obtain from both plants and animals. The main constituents of fats and oils are triglycerides comprising of fatty acids and a glycerol. Oils control the evaporation of moisture from the skin, spread easily and evenly and are partly metabolised in the skin to release valuable fatty acids (Fang et al., 2004:170,173; Lautenschläger, 2004:46; Mitsui, 1997:121-122). The focus of this study was not formulation per se, but included the formulation of avocado-, grapeseed-, emu-, crocodile, olive and coconut oil into semisolid emulgel- and two foam formulations. This was done in order to investigate the penetration enhancing properties of their fatty acid content on flurbiprofen which was chosen as the marker API. The emulgels containing the natural oils were compared to the same emulgel formulation containing liquid paraffin, and a hydrogel without the inclusion of an oil. Six natural oils were analysed by gas chromatography (GC) in order to quantify their fatty acid compositions, whilst also providing qualitative information by indicating the retention times of the materials with an alkyl chain composition (Mitsui, 1997:260). Data obtained with the GC indicated that olive- (76%), avocado- (68%), emu- (46%) and crocodile oil (40%) presented with high levels of oleic acid, also known as a mono-unsaturated fatty acid (MUFA). Lower levels of oleic acid were observed within grapeseed- (27%) and coconut oil (8%). The only oil demonstrating high levels of the poly-unsaturated fatty acid (PUFA), linoleic acid, was grapeseed oil (61%), whereas the remainder of the oils showed levels below 24%. Contrary, coconut oil seemed to have been the only oil high in saturated fatty acids (SFAs) and consisted of a lauric acid content of 52% and medium levels of myristic acid (21%). Average levels of palmitic acid (SFA) were found in crocodile- (21%) and in emu oil (21%), both of animal origin, whereas avocado-, grapeseed-, olive- and coconut oils from plants presented with levels below 15%. Stearic acid was also present in levels below 10% in all of these oils, with the oils of animal origin portraying the highest values. A method was developed and validated to determine the concentration of the marker flurbiprofen after diffusion from the formulations into the skin, as well as concentrations of the marker that diffused through the skin, by means of high performance liquid chromatography (HPLC). Franz cell membrane diffusion studies were conducted prior to the skin diffusion studies in order to verify the actual release of the marker from the semisolid formulations. Skin diffusion experiments were performed using dermatomed excised, human skin to which the six emulgel formulations, containing the natural oils, were applied. A comparative study was performed utilising liquid paraffin and a hydrogel, in order to compare the diffusion of the marker, flurbiprofen, into and through the skin. The two oil emulgel formulations that had indicated the best flux values were subsequently formulated into foam preparations in order to compare the penetration enhancement properties on flurbiprofen of these two oils in a foam preparation, to those in the equivalent emulgels. The data generated for all ten the formulations were compared, and the formulations that yielded the best results with regards to median flux values and the flurbiprofen concentrations within the stratum corneum-epidermis and epidermis-dermis, were identified. Application of the liquid paraffin emulgel (21.29 μg/ml) depicted the highest average concentration of the diffused lipophilic flurbiprofen within the stratum corneum-epidermis, followed by the olive oil foam (21.47 μg/ml), olive oil emulgel (17.82 μg/ml) and grapeseed oil emulgel (17.78 μg/ml). Very similar concentrations for the marker were demonstrated by the hydrogel (16.73 μg/ml) and crocodile oil emulgel (14.89 μg/ml), whereas a lower concentration was shown for coconut oil emulgel (7.18 μg/ml). The remainder of the formulations yielded concentrations below 3%, i.e. the avocado oil emulgel (2.72 μg/ml), the coconut oil foam (1.57 μg/ml) and finally the emu oil emulgel (1.25 μg/ml). The penetration of the marker, flurbiprofen, being trapped within the skin seemed to have been enhanced more by the oleic acid (UFA) containing emulgels and foam, especially. This was followed by oils containing high linoleic acid values, which indicated that the more kinked shaped the fatty acids, the more difficult it became to insert themselves within the lipid structures of the stratum corneum, with a resulting accumulation of the marker (Fang et al., 2003:318-319). It therefore seemed that those oils that predominantly consisted of unsaturated fatty acids (UFAs) (grapeseed-, crocodile- and olive oils) seemed to have increased the concentration of the diffused marker more significantly than those oils containing an almost even combination of MUFAs and PUFAs (avocado oil), or those mainly consisting of SFAs (coconut oil). Average concentrations of the diffused flurbiprofen found in the epidermis-dermis region of the skin for all of the formulations demonstrated low concentrations, ranging between 0.97 - 5.39 μg/ml, with the exception of the emu oil emulgel that presented with a higher concentration of 16.15 μg/ml. The reason for the high accumulation of the marker might have been as a result of epidermal proliferation, with subsequent accumulation of the marker within the epidermis-dermis due to high oleic- and linoleic acid values, as well as small amounts of palmitoleic acid present within this oil (Katsuta et al., 2005:1011). The resistance of the epidermis-dermis region to the general permeation of flurbiprofen might have been caused by its lipophilic nature, resulting in a reduced solubility within the hydrophilic environment of this region (Hadgraft, 1999:5). Median results from the skin diffusion studies demonstrated that the hydrogel (23.79 μg/cm2.h) had the highest flux, followed by the olive oil- (17.99 μg/cm2.h), liquid paraffin- (15.70 μg/cm2.h), coconut oil- (13.16 μg/cm2.h), grapeseed oil- (11.85 μg/cm2.h), avocado oil- (8.31 μg/cm2.h), crocodile oil- (6.68 μg/cm2.h) and emu oil emulgels (4.41 μg/cm2.h). The fact that the hydrogel presented a higher flux value for the marker could have been as a result of its high water content that had caused hydration of the skin. Hydration opens up the dense lipid structures inside of the stratum corneum, due to swelling of the corneocytes, with a subsequent increase in the marker‘s flux (Benson, 2005:28; Ranade & Hollinger, 2004:213). The high flux value of flurbiprofen with the liquid paraffin emulgel might also have resulted from the fact that it occluded the skin, which increased the hydration of the stratum corneum, with a subsequent increase in the flux (Mitsui, 1997:124; Thomas & Finnin, 2004:699). Results from the skin diffusion studies could be explained by the fact that the fatty acids differ in their hydrocarbon chain by (1) the length of the chain, and (2) the position- and number of the double bonds (Babu et al., 2006:144). It is suggested that fatty acids with hydrocarbon (lipophilic) chains between C12 to C14 (also present within coconut oil) have an optimal balance of the partition coefficient and its affinity for the skin (Ogiso & Shintani, 1990:1067). It appears as though the branched UFAs, especially oleic acid, present in high quantities in olive oil, were more powerful enhancers of the diffusion of the marker, flurbiprofen (Chi et al., 1995:270). Foam formulations were manufactured with the olive- and coconut oil emulgels that had demonstrated the best median flux values of flurbiprofen from the natural oil emulgel formulations. These formulated foams, however, did not significantly increased flux values for flurbiprofen through the skin, but only achieved values of 5.56 μg/cm2.h for the olive oil foam and 4.36 μg/cm2.h for the coconut oil foam formulations. The low flux values could have been attributed to the nature of the formulation itself, which was filled with trapped air that could have resulted in the formulation not making optimal direct contact with the available skin surface. Throughout this study, it became evident that olive oil, predominantly consisting of oleic acid (UFA), was most effective in enhancing the flux of the lipophilic marker, flurbiprofen, through the skin, closely followed by coconut oil consisting of SFAs, with lauric- and myristic acid as its main constituents. Better enhancement effects were observed with those oils containing high amounts of oleic acid (MUFA), than oils consisting of almost equal amounts of both PUFAs and MUFAs (avocado-, emu- and crocodile oil), or oils mainly consisting of PUFAs (grapeseed oil) as its main components, but their effect was not more significant than the oil containing SFAs (coconut oil) as its key components. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

In pharmaceutical sciences, topical delivery is a transport process of an active pharmaceutical ingredient (API) from a formulated dosage form to the target site of action. For most topical delivery systems, the skin surface, or the specific skin layers, such as the outermost layer of the stratum corneum, the lipids amid the corneocytes within the stratum corneum, the corneocytes themselves, the epidermis, dermis, Langerhans cells, Merckle cells or the appendageal structures can be the target delivery location. When an API is delivered to the skin, it has to firstly diffuse from the formulation in which it is applied, to the skin surface. From there the API may partition into the stratum corneum, permeate across the stratum corneum and partition into the viable epidermis, from where it may partition further into the dermis and permeate across the dermis into the bloodstream (Wiechers, 2008:1-3, 7). With respect to the barrier function of the skin, the intercellular spaces within the stratum corneum contain lipids and its main purpose is to operate as a barrier to water-loss and to provide an imperative diffusional barrier to the absorption of APIs. This resistance is comprised of a complex interaction of lipids that creates a hydrophilic and lipophilic penetration pathway. The fundamental aspect underlying the impermeability of the skin, therefore, is the lipophilic nature of the stratum corneum (Bouwstra et al., 2003:4; Franz & Lehman, 2000:25; Walker & Smith, 1996:296). A common approach for the promotion of poorly penetrating APIs in transdermal delivery is the incorporation of chemical penetration enhancers in delivery systems, in order to promote the partitioning of an API into the stratum corneum. These chemicals are also referred to as accelerants, promoters and absorption promoters. Penetration enhancers are added to topical formulations and usually also partition into the stratum corneum, where they temporarily and reversibly disrupt its fundamental diffusional barrier properties, hence facilitating the absorption of an API through the skin (Büyüktimkin et al., 1997:358-359; Sinha & Kaur, 2000:1131; Walker & Smith, 1996:296). The mechanisms for the enhancement of diffusion of the API should therefore increase the solubility and partitioning of the drug from the formulation into the skin. It should further increase the solubility of the API within the skin and promote its permeability and diffusion coefficient (Rajadhyaksha et al., 1997:489). Fatty acids are recognised to effectively enhance the penetration of transdermally delivered hydrophilic and lipophilic APIs. Many penetration enhancers contain saturated and unsaturated hydrocarbon chains, and a popular fatty acid that has been used in this regard is oleic acid (Williams & Barry, 2004:609-610). It is believed that fatty acids disrupt the lipid organisation of the intercellular lipids within the stratum corneum to cause fluidisation of these bilayers, making the stratum corneum more permeable to APIs. Excipients with polar (hydrophilic) head groups and long hydrophobic chains i.e. fatty acids, can penetrate into the intercellular lipids of the stratum corneum and disrupt these endogenous lipid components, thereby increasing diffusion of an API within the skin (Barry, 2006:9-10; Hadgraft & Finnin, 2006:367-368; Kanikkannan et al., 2006:18; Williams & Barry, 2004:610). Natural oils are widely used in topical formulations and were an obvious choice in this study. Oils are liquids at room temperature, whereas fats are in solid form. They are relatively easy to obtain from both plants and animals. The main constituents of fats and oils are triglycerides comprising of fatty acids and a glycerol. Oils control the evaporation of moisture from the skin, spread easily and evenly and are partly metabolised in the skin to release valuable fatty acids (Fang et al., 2004:170,173; Lautenschläger, 2004:46; Mitsui, 1997:121-122). The focus of this study was not formulation per se, but included the formulation of avocado-, grapeseed-, emu-, crocodile, olive and coconut oil into semisolid emulgel- and two foam formulations. This was done in order to investigate the penetration enhancing properties of their fatty acid content on flurbiprofen which was chosen as the marker API. The emulgels containing the natural oils were compared to the same emulgel formulation containing liquid paraffin, and a hydrogel without the inclusion of an oil. Six natural oils were analysed by gas chromatography (GC) in order to quantify their fatty acid compositions, whilst also providing qualitative information by indicating the retention times of the materials with an alkyl chain composition (Mitsui, 1997:260). Data obtained with the GC indicated that olive- (76%), avocado- (68%), emu- (46%) and crocodile oil (40%) presented with high levels of oleic acid, also known as a mono-unsaturated fatty acid (MUFA). Lower levels of oleic acid were observed within grapeseed- (27%) and coconut oil (8%). The only oil demonstrating high levels of the poly-unsaturated fatty acid (PUFA), linoleic acid, was grapeseed oil (61%), whereas the remainder of the oils showed levels below 24%. Contrary, coconut oil seemed to have been the only oil high in saturated fatty acids (SFAs) and consisted of a lauric acid content of 52% and medium levels of myristic acid (21%). Average levels of palmitic acid (SFA) were found in crocodile- (21%) and in emu oil (21%), both of animal origin, whereas avocado-, grapeseed-, olive- and coconut oils from plants presented with levels below 15%. Stearic acid was also present in levels below 10% in all of these oils, with the oils of animal origin portraying the highest values. A method was developed and validated to determine the concentration of the marker flurbiprofen after diffusion from the formulations into the skin, as well as concentrations of the marker that diffused through the skin, by means of high performance liquid chromatography (HPLC). Franz cell membrane diffusion studies were conducted prior to the skin diffusion studies in order to verify the actual release of the marker from the semisolid formulations. Skin diffusion experiments were performed using dermatomed excised, human skin to which the six emulgel formulations, containing the natural oils, were applied. A comparative study was performed utilising liquid paraffin and a hydrogel, in order to compare the diffusion of the marker, flurbiprofen, into and through the skin. The two oil emulgel formulations that had indicated the best flux values were subsequently formulated into foam preparations in order to compare the penetration enhancement properties on flurbiprofen of these two oils in a foam preparation, to those in the equivalent emulgels. The data generated for all ten the formulations were compared, and the formulations that yielded the best results with regards to median flux values and the flurbiprofen concentrations within the stratum corneum-epidermis and epidermis-dermis, were identified. Application of the liquid paraffin emulgel (21.29 μg/ml) depicted the highest average concentration of the diffused lipophilic flurbiprofen within the stratum corneum-epidermis, followed by the olive oil foam (21.47 μg/ml), olive oil emulgel (17.82 μg/ml) and grapeseed oil emulgel (17.78 μg/ml). Very similar concentrations for the marker were demonstrated by the hydrogel (16.73 μg/ml) and crocodile oil emulgel (14.89 μg/ml), whereas a lower concentration was shown for coconut oil emulgel (7.18 μg/ml). The remainder of the formulations yielded concentrations below 3%, i.e. the avocado oil emulgel (2.72 μg/ml), the coconut oil foam (1.57 μg/ml) and finally the emu oil emulgel (1.25 μg/ml). The penetration of the marker, flurbiprofen, being trapped within the skin seemed to have been enhanced more by the oleic acid (UFA) containing emulgels and foam, especially. This was followed by oils containing high linoleic acid values, which indicated that the more kinked shaped the fatty acids, the more difficult it became to insert themselves within the lipid structures of the stratum corneum, with a resulting accumulation of the marker (Fang et al., 2003:318-319). It therefore seemed that those oils that predominantly consisted of unsaturated fatty acids (UFAs) (grapeseed-, crocodile- and olive oils) seemed to have increased the concentration of the diffused marker more significantly than those oils containing an almost even combination of MUFAs and PUFAs (avocado oil), or those mainly consisting of SFAs (coconut oil). Average concentrations of the diffused flurbiprofen found in the epidermis-dermis region of the skin for all of the formulations demonstrated low concentrations, ranging between 0.97 - 5.39 μg/ml, with the exception of the emu oil emulgel that presented with a higher concentration of 16.15 μg/ml. The reason for the high accumulation of the marker might have been as a result of epidermal proliferation, with subsequent accumulation of the marker within the epidermis-dermis due to high oleic- and linoleic acid values, as well as small amounts of palmitoleic acid present within this oil (Katsuta et al., 2005:1011). The resistance of the epidermis-dermis region to the general permeation of flurbiprofen might have been caused by its lipophilic nature, resulting in a reduced solubility within the hydrophilic environment of this region (Hadgraft, 1999:5). Median results from the skin diffusion studies demonstrated that the hydrogel (23.79 μg/cm2.h) had the highest flux, followed by the olive oil- (17.99 μg/cm2.h), liquid paraffin- (15.70 μg/cm2.h), coconut oil- (13.16 μg/cm2.h), grapeseed oil- (11.85 μg/cm2.h), avocado oil- (8.31 μg/cm2.h), crocodile oil- (6.68 μg/cm2.h) and emu oil emulgels (4.41 μg/cm2.h). The fact that the hydrogel presented a higher flux value for the marker could have been as a result of its high water content that had caused hydration of the skin. Hydration opens up the dense lipid structures inside of the stratum corneum, due to swelling of the corneocytes, with a subsequent increase in the marker‘s flux (Benson, 2005:28; Ranade & Hollinger, 2004:213). The high flux value of flurbiprofen with the liquid paraffin emulgel might also have resulted from the fact that it occluded the skin, which increased the hydration of the stratum corneum, with a subsequent increase in the flux (Mitsui, 1997:124; Thomas & Finnin, 2004:699). Results from the skin diffusion studies could be explained by the fact that the fatty acids differ in their hydrocarbon chain by (1) the length of the chain, and (2) the position- and number of the double bonds (Babu et al., 2006:144). It is suggested that fatty acids with hydrocarbon (lipophilic) chains between C12 to C14 (also present within coconut oil) have an optimal balance of the partition coefficient and its affinity for the skin (Ogiso & Shintani, 1990:1067). It appears as though the branched UFAs, especially oleic acid, present in high quantities in olive oil, were more powerful enhancers of the diffusion of the marker, flurbiprofen (Chi et al., 1995:270). Foam formulations were manufactured with the olive- and coconut oil emulgels that had demonstrated the best median flux values of flurbiprofen from the natural oil emulgel formulations. These formulated foams, however, did not significantly increased flux values for flurbiprofen through the skin, but only achieved values of 5.56 μg/cm2.h for the olive oil foam and 4.36 μg/cm2.h for the coconut oil foam formulations. The low flux values could have been attributed to the nature of the formulation itself, which was filled with trapped air that could have resulted in the formulation not making optimal direct contact with the available skin surface. Throughout this study, it became evident that olive oil, predominantly consisting of oleic acid (UFA), was most effective in enhancing the flux of the lipophilic marker, flurbiprofen, through the skin, closely followed by coconut oil consisting of SFAs, with lauric- and myristic acid as its main constituents. Better enhancement effects were observed with those oils containing high amounts of oleic acid (MUFA), than oils consisting of almost equal amounts of both PUFAs and MUFAs (avocado-, emu- and crocodile oil), or oils mainly consisting of PUFAs (grapeseed oil) as its main components, but their effect was not more significant than the oil containing SFAs (coconut oil) as its key components. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.