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In this study, submicron emulsions have been employed as a carrier for the topical application of kaempferol. The effect of components of submicron emulsions on the physicochemical properties and permeation capability of drug were evaluated. In case of drug-loaded submicron emulsions, the cumulative amount over 12 h (Q(12 h)), lag time and deposition in skin amount ranged from 13.0±3.4 to 236.1±21.2 µg/cm(2), 1.7 to 5.3 h, and 1.10 to 7.76 µg/cm(2), respectively, which indicated that the permeation parameters of kaempferol were markedly influenced by the component ratio. Kaempferol dispensed in isopropyl myristate was used as the control. The Q(12 h), lag time and deposition amount in skin were 4.2±1.8 µg/cm(2), 6.0 h and 2.25±0.60 µg/cm(2), respectively. The data showed that used appropriate submicron emulsions as vehicle could significantly increase the Q(12 h) and deposition amount in skin and shorten the lag time, demonstrating that submicron emulsions have a potent enhancement effect for kaempferol transdermal delivery.

The aim of this study was to optimize hesperetin cream formulations by in vitro permeation study and evaluate topical whitening active effect and skin irritation by in vivo study. The results showed that the solubility of lipophilic compound of hesperetin was increased by short-chain alcohol including ethanol, glycerin, propylene glycol and polyethylene glycols 400 (PEG 400). PEG 400 showed strongest solubilized effect by increased 3400-fold. With the addition of 5% enhancers, it was found that menthol showed the most potent enhancing effect, followed by azone and depigmentation agents (linoleic acid and lecithin). Moreover, enhancers could shorten the lag time from 3.7 to 1 h. Combination of menthol, linoleic acid and lecithin of 2.5% had a higher permeation rate of 9.8 microg/cm(2)/h and lower lag time 1 h, therefore the formulation was selected to process the skin whitening and irritation test. The results showed that a significantly topical photoprotective effect with acceptable skin irritation was obtained after hesperetin cream topical application when compared with that of the non-treatment group, indicating that the hesperetin cream may be used as an effective whitening agent.

The objective of this study was to examine the transdermal delivery of sodium nonivamide acetate (SNA) using iontophoresis and electroporation with ultra high molecular weight polyethylene membranes (Solupor) to achieve controlled transdermal drug delivery. A derivative of SNA, sodium nonivamide propionate (SNP), was also used as a model drug in this investigation. Iontophoresis increased the transdermal permeation of SNA as compared to passive diffusion. Most Solupor membranes were rate-limiting for the iontophoretic permeation of SNA except for Solupor 8P07, which showed negligible resistance to SNA delivery. The tortuosity (Gurley number), pore size, and the current density-induced attachments on the surface of the Solupor membranes may have been important for their rate-controlling effect. The trends for inhibiting or controlling SNA permeation were similar for both iontophoretic and electroporation applications. The higher molecular size and lower hydrophilicity of SNP compared to SNA resulted in lower permeation of SNP using electrically-assisted methods. Moreover, the various types of Solupor membranes showed similar trends for both SNA and SNP. This present study indicates that Solupor membranes act as rate-limiting membranes for controlling the release and skin permeation of both SNA and SNP by electrically-assisted methods.

The purpose of this study was to develop propranolol extended release formulations containing hydroxypropylmethylcellulose (HPMC). The results indicate that the drug release from the tablet form containing a high amount of HPMC was incomplete, and avicel addition could increase the release percent at a later stage. In order to readily obtain an optimal formulation, response surface methodology and multiple response optimization utilizing a quadratic polynomial equation was used. The model formulations were prepared according to a factorial design. The effects of causal factors including the HPMC/drug ratio (X1) and avicel level (X2), on drug release were also measured. The drug release percentage at 1.5, 4, 8, 14 and 24 h were the target response and were restricted to not more than 25%, 35-50%, 55-70%, 75-90%, and 95-110%, respectively. The results showed that the optimized formulation provided a dissolution pattern equivalent to the predicted curve, which indicated that the optimal formulation could be obtained using response surface methodology. The mechanism of drug release from HMPC matrices tablets followed quasi-Fickian diffusion.

Blood glucose levels are routinely obtained by invasive and painful methods using glucose meters and test strips. The development of less invasive or non invasive techniques would be beneficial for diabetes patients. In this study, a noninvasive method was evaluated using the back diffusion of glucose across skin with or without permeation enhancement methods. An in vitro model was utilized. The stratum corneum (SC) was the predominant barrier for both back and forward diffusion of glucose across skin. Surfactants with various charges and essential oils (cyclic monoterpenes) were used as chemical enhancers to promote the back diffusion of glucose. A cationic surfactant (benzalkonium chloride) showed the highest enhancement, followed by anionic and nonionic surfactants. d-Limonene and 1,8-cineole dispersed in appropriate proportions of ethanol could enhance the glucose diffusion after pretreatment of the skin surface. Electroporation, defined as a physical method, significantly increased the amount of glucose that diffused back. The percentages of diffused glucose by 300 V (volts) and 500 V high voltage pulses on skin for 10 min were found to be 45 and 75 times greater than the control group, respectively.

The in vitro permeation of three diclofenac salts--diclofenac sodium (DFS), diclofenac potassium (DFP) and diclofenac diethylammonium (DFD)-across skin by both passive and iontophoretic transport were investigated. Various skin types were used as the barriers to elucidate the mechanism controlling transdermal delivery of diclofenac salts. The importance of the intercellular (paracellular) route for both DFS and DFP in passive permeation was elucidated. The transfollicular route constitutes an important permeation pathway for DFS but not for DFP. The route and mechanism for transdermal iontophoresis of DFD across the skin was somewhat different to that of the other salts. Hair follicles may be a more important pathway for DFD than for DFS and DFP under iontophoresis, while the intercellular lipid pathway showed the opposite result. Combination of iontophoresis and a penetration enhancer, cardamom oil, did not show a synergistic effect on diclofenac salt permeation. The results of this investigation suggest that the transdermal mechanism and the route of diclofenac salt uptake via passive and iontophoretic transport can be affected by their counterions.

The in vitro and in vivo effect of pretreatment by cardamom oil, a crude drug extract, in ethanol/water vehicles on the transdermal delivery of indomethacin was investigated. The cyclic monoterpene components in cardamom oil were also determined and quantified in this study. The permeation of indomethacin was significantly enhanced after pretreatment of cardamom oil both in the in vitro and in vivo studies. The result of various pre-treatment periods showed that the indomethacin flux decreased as the length of the pretreatment increased. Both natural cardamom oil and a cyclic monoterpene mixture composed of the components of the oil showed similar enhancement on indomethacin permeation, indicating cyclic monoterpenes are the predominant components altering the barrier property of stratum corneum. The results also showed that three minor components in cardamom oil (alpha-pinene, 6.5%; beta-pinene, 4.8%; alpha-terpineol, 0.4%) had a synergistic effect with 1,8-cineole (59.3%) and d-limonene (29.0%) to enhance the permeation of indomethacin.

The aim of this study was to investigate the transdermal iontophoresis of a newly designed capsaicin derivative, sodium nonivamide propionate (SNP). The iontophoretic permeation of SNP from various pH buffers increased following the decrease of pH values. This trend was consistent with that of sodium nonivamide acetate (SNA) which is another synthetic analogue of capsaicin. However, the iontophoretic permeability of SNP was much lower than that of SNA. SNP was also delivered iontophoretically from hydrogel formulations. It is suggested that ionizable polymers should be avoided for iontophoretic delivery to maintain good penetration capacity of drugs. Both nonionic cellulose polymers of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) showed higher iontophoretic flux for SNP than the others did. Furthermore, the flux of SNP leveled off with an increase in the amount of polymers in hydrogel, indicating that the viscosity of vehicles plays an important role in the permeation of SNP. Comparing the various iontophoretic application modes, the discontinuous on/off cyclic mode showed higher penetration capacity than did the continuous mode although they possessed the same electrical energy. Moreover, the desorption time of SNP from skin was approximately 20 min which was longer than that of SNA.

Sodium nonivamide acetate (SNA) is a newly synthetic analogue of capsaicin which produces no overt pungent sensation or irritation. In this present study, the effects and roles of penetration enhancers for SNA through rat skin were investigated by in vitro skin penetration experiment and differential scanning calorimeter (DSC) determination. The penetration fluxes of SNA after the incorporation of enhancers increased in the order of Polysorbate 20sodium laurylsulfateor = benzalkonium chloride. This result was consistent with that of DSC profiles which indicated the disruptive effects of surfactants on the rat stratum corneum increased in the order of Polysorbate 20sodium laurylsulfatebenzalkonium chloride. The information gained is particularly helpful in the development of SNA transdermal drug delivery system.