In this thesis, a series of in vitro diffusion studies were performed to evaluate the transmembrane permeation of picaridin and oxybenzone across human epidermis and poly(dimethylsiloxane) (PDMS) membrane. Transdermal permeation of picaridin and oxybenzone from four commercially available repellent and sunscreen products was also investigated by using different application concentrations and sequences. The results obtained were then compared to those of the repellent DEET and the sunscreen oxybenzone under identical experimental conditions. Permeation of picaridin and oxybenzone across human epidermis was suppressed when both compounds were used concurrently. Increasing concentration of the test compounds further reduced the permeation percentage of picaridin and oxybenzone. While permeation characteristics were correlative between human epidermis and artificial PDMS membrane, permeability of PDMS membrane was significantly larger than that of human epidermis. This finding was different from concurrent use of DEET and oxybenzone in which a synergistic permeation enhancement was observed between the two substances. Transdermal permeation of picaridin across human epidermis from various commercially available spray preparations was significantly lower than that of DEET from similar spray products, both alone and in combination with sunscreen oxybenzone. Concurrent application of the commercial products resulted in either no change or suppression of permeation of picaridin and oxybenzone. This finding was also different from concurrent application of DEET and oxybenzone using commercial preparations. In addition, permeation of picaridin and oxybenzone across human epidermis was dependent on application concentration, use sequence, and preparation type.It was concluded from this thesis that picaridin would be a better candidate for concurrent application with sunscreen preparations in terms of percutaneous permeation.

In this thesis, a series of in vitro diffusion studies were performed to evaluate the transmembrane permeation of picaridin and oxybenzone across human epidermis and poly(dimethylsiloxane) (PDMS) membrane. Transdermal permeation of picaridin and oxybenzone from four commercially available repellent and sunscreen products was also investigated by using different application concentrations and sequences. The results obtained were then compared to those of the repellent DEET and the sunscreen oxybenzone under identical experimental conditions. Permeation of picaridin and oxybenzone across human epidermis was suppressed when both compounds were used concurrently. Increasing concentration of the test compounds further reduced the permeation percentage of picaridin and oxybenzone. While permeation characteristics were correlative between human epidermis and artificial PDMS membrane, permeability of PDMS membrane was significantly larger than that of human epidermis. This finding was different from concurrent use of DEET and oxybenzone in which a synergistic permeation enhancement was observed between the two substances. Transdermal permeation of picaridin across human epidermis from various commercially available spray preparations was significantly lower than that of DEET from similar spray products, both alone and in combination with sunscreen oxybenzone. Concurrent application of the commercial products resulted in either no change or suppression of permeation of picaridin and oxybenzone. This finding was also different from concurrent application of DEET and oxybenzone using commercial preparations. In addition, permeation of picaridin and oxybenzone across human epidermis was dependent on application concentration, use sequence, and preparation type.It was concluded from this thesis that picaridin would be a better candidate for concurrent application with sunscreen preparations in terms of percutaneous permeation.

This thesis investigates the role of prior use in common and statutory trade mark law. In the United States a pertinent requirement is priority of use. In the United Kingdom and South Africa, a reputation must be present. In the United Kingdom a plaintiff is required to have goodwill in the country, but in the United States and South Africa it is not required. The conception of a mark does not qualify for protection. It is not required that a business must have actually entered the market. In the United States the general approach is that a plaintiff will not receive protection in a remote area, but regard must be had to zones of natural expansion. British and South African law is the same, and protection may be obtained in areas where there is no trading. Where a dual reputation exists, neither party will be able to act against the other. The mere fact that the user of a mark was aware of the use thereof by another person, does not exclude protection. A trade mark application can be opposed on the basis of another application, combined with use of a mark, or on the ground of prior use. In some instances the fact that a mark has been filed will influence the burden of proof. In general, a registration can be expunged on the same grounds as would constitute grounds of opposition. The concurrent use of a mark can form the basis for the registration of a mark. In the United States, the use must have taken place prior to the filing date of the other party, but in the United Kingdom and South Africa, prior to the own filing date. In the latter two countries, knowledge of a mark is not necessarily exclusionary. Prior use is generally accepted as a defence to an infringement action. It is, however, noted that in various countries, it is only use prior to the relevant date that will be protected, and there is not necessarily a right to extend the scope of use concerned. / Mercantile Law / LL.D. (Mercantile Law)

This thesis investigates the role of prior use in common and statutory trade mark law. In the United States a pertinent requirement is priority of use. In the United Kingdom and South Africa, a reputation must be present. In the United Kingdom a plaintiff is required to have goodwill in the country, but in the United States and South Africa it is not required. The conception of a mark does not qualify for protection. It is not required that a business must have actually entered the market. In the United States the general approach is that a plaintiff will not receive protection in a remote area, but regard must be had to zones of natural expansion. British and South African law is the same, and protection may be obtained in areas where there is no trading. Where a dual reputation exists, neither party will be able to act against the other. The mere fact that the user of a mark was aware of the use thereof by another person, does not exclude protection. A trade mark application can be opposed on the basis of another application, combined with use of a mark, or on the ground of prior use. In some instances the fact that a mark has been filed will influence the burden of proof. In general, a registration can be expunged on the same grounds as would constitute grounds of opposition. The concurrent use of a mark can form the basis for the registration of a mark. In the United States, the use must have taken place prior to the filing date of the other party, but in the United Kingdom and South Africa, prior to the own filing date. In the latter two countries, knowledge of a mark is not necessarily exclusionary. Prior use is generally accepted as a defence to an infringement action. It is, however, noted that in various countries, it is only use prior to the relevant date that will be protected, and there is not necessarily a right to extend the scope of use concerned. / Mercantile Law / LL.D. (Mercantile Law)