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Molecules 2017, 22(11), 2022; doi:10.3390/molecules22112022

Microneedle-Assisted Percutaneous Delivery of a Tetramethylpyrazine-Loaded Microemulsion

School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
Jiangsu Provincial TCM Engineering Technology Research Center for Highly Efficient Drug Delivery Systems (DDS), Nanjing 210023, China
School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, China
Shanghai Hutchison Pharmaceuticals Limited, Shanghai 200001, China
These authors contributed equally to this work.
Author to whom correspondence should be addressed.
Received: 23 September 2017 / Accepted: 15 November 2017 / Published: 21 November 2017
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This study examined the efficacy of the percutaneous delivery of a tetramethylpyrazine-loaded microemulsion (TMP-ME) on skin pretreated with microneedles (MN). The TMP-ME formulation was optimized in vitro with skin permeation experiments, using a uniform experimental design, guided by a pseudo-ternary phase diagram, in which the TMP skin permeation level and mean particle size were indices. The effects of MN pretreatment on skin permeation by TMP-ME were assessed using in vitro skin permeation, in vivo skin microdialysis, and pharmacokinetic studies in rats. The influence of MN pretreatment on the skin barrier function was evaluated by measuring the electrical resistance of rat skin before and after MN insertion. In the optimal formulation of TMP-ME, the weight percentages of Maisine® 35-1 (oil phase), Labrasol® (surfactant), and Transcutol® P (co-surfactant) were 7%, 30% and 10%, respectively, with 1.5% TMP loading. In the in vitro skin permeation study, MN-assisted TMP-ME exhibited a two-fold increase in a 24-h cumulative TMP permeation compared with TMP-ME alone (p < 0.05). In the skin microdialysis study, TMP in MN-assisted TMP-ME exhibited a 1.25-fold increase in Cmax, a 0.93-fold decrease in Tmax, and a 0.88-fold increase in AUC0–t (p < 0.05). Similarly, in the pharmacokinetic study, TMP in MN-assisted TMP-ME exhibited a 2.11-fold increase in Cmax, a 0.67-fold decrease in Tmax, and a 1.07-fold increase in AUC0–t (p < 0.05). The percutaneous electrical resistance of rat skin before and after MN insertion was 850 ± 50 Ω/cm2 and 283 ± 104 Ω/cm2 respectively, indicating that MN dramatically compromises the skin barrier. These results suggest that MN assistance increases the skin permeation rate and the extent of percutaneous absorption of TMP-ME, and that the mechanism may involve the reversible barrier perturbation effect. The rate and extent of percutaneous absorption of TMP-ME can be significantly enhanced by MN assistance, possibly because MN causes a reversible barrier perturbation effect on skin. View Full-Text
Keywords: microneedle; microemulsion; tetramethylpyrazine; skin permeation microneedle; microemulsion; tetramethylpyrazine; skin permeation

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Zu, Q.; Yu, Y.; Bi, X.; Zhang, R.; Di, L. Microneedle-Assisted Percutaneous Delivery of a Tetramethylpyrazine-Loaded Microemulsion. Molecules 2017, 22, 2022.

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