الفهرس 
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Abstract
The aim of the present study was to evaluate the combination of microneedle pretreatment and iontophoresis for the potential to increase skin permeation of methylene blue as a model compound. Three different arrays of microneedle electrodes was used (triangular, circular, parallel) and the effect of microneedle pretreatment and iontophoresis on the in vitro permeability of Methlene blue was evaluated by measuring methylene blue transported, accumulative amount of MB, flux rate, pore diameter and penetration depth of MB through excised rat skin.
1- Experimental groups: nine experimental groups were formed as follows,
GI: 6 volt IP + circular array MN electrodes.
GII: 6 volt IP + triangular array MN electrodes.
GIII: 6 volt IP + parallel array MN electrodes.
GIV: 9 volt IP + circular array MN electrodes.
GV: 9 volt IP + triangular array MN electrodes.
GVI: 9 volt IP + parallel array MN electrodes.
GVII: 12 volt IP + circular array MN electrodes.
GVIII: 12 volt IP + triangular array MN electrodes.
GIX: 12 volt IP + parallel array MN electrodes.
2- The electric field analysis (homogeneity and distribution) will be done using a specific computer programme.(20)
3- The following measurements will be done for each sample:
the area under the MN electode array will be cut carefully rinsed in water several times, weighted and dissolved for quantitative determination of MB .(21)
4- Penetration depth of MB will be determined throughout the skin thickness using light microscope with digital camera.
Conclusions:
The following results are obtained:-
1. Increasing volt decreasing the average cumulative amount delivered(μg MB per cm2)at 5 EP followed by DC-Iontophoresis (Square wave, 0.5A for 2hrs) for different studied groups.
2. Increasing volt decreasing MB amount delivered(μg per mg tissue)at 5 EP followed by DC-Iontophoresis (Square wave, 0.5A for 2hrs) for different studied groups.
3. Increasing volt decreasing the average MB flux(μg / cm2/120)at 5 EP followed by DC-Iontophoresis (Square wave, 0.5A for 2hrs) for different studied groups.
4. Both Pore diameter of the skin and Penetration depth of MB through the skin decrease with increasing the Volt for different studied groups.
5. With increasing Volts decrease both of Pore diameter and Penetration depth with MB amount, Average accumulative MB concentration and MB Flux for different studied groups.
6. The hightest values of Pore diameter and Penetration depth with MB amount, Average accumulative MB concentration and MB Flux at 6volt with Parallel Electrode in compare with Triangular Electrode and Circular Electrode at 9 and 12Volts.
Finally the pulsed electric fields of common (low cost) may have important applications for drug delivery in a variety of fields where topical drug delivery is a goal.