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Combination of Microneedles with Other Methods
Published in Boris Stoeber, Raja K Sivamani, Howard I. Maibach, Microneedling in Clinical Practice, 2020
Katikaneni et al. studied the in vitro delivery of a 13-kDa peptide using the combination with respect to the mechanism dominating the transport during iontophoresis (22). Tape stripping wherein the stratum corneum is completely removed resulted in a complete impairment of electroosmosis, thus altering the skin's permselective properties. This study showed that partial breaching of the skin barrier as it happens during microporation did not impede electroosmosis. In vitro skin flux of the peptide was found to be higher when microneedles and iontophoresis were used in conjunction. A total cumulative amount of 700 ng/cm2 and 25 µg/cm2 of the peptide was delivered for the two formulations evaluated at pH 7.5 and pH 4.0 respectively. There were no detectable levels of the peptide when iontophoresis was applied across intact skin. It was established in this case that delivery across microporated skin was higher when electrorepulsion was the dominant force during iontophoresis as compared to electroosmosis. An in vivo study conducted on the same peptide resulted in similar results (25). Daniplestim concentration in the patch was 2 mg/mL. Combination of microneedles and iontophoresis resulted in a Cmax of about 9 ng/mL. Peptide delivery with iontophoresis or microneedles alone was negligible.
Iontophoresis for Local Anesthesia
Published in Marwali Harahap, Adel R. Abadir, Anesthesia and Analgesia in Dermatologic Surgery, 2019
The likely principal mechanism for drug delivery in iontophoresis is electromigration (7). Ionic penetration likely occurs via aqueous pores, such as hair follicles and sweat ducts, as well as sebaceous glands and skin imperfections (10). Skin permeability may be altered by the application of electric current facilitating drug delivery. Finally, in some cases, electroosmosis may occur whereby the ions are carried across the skin in conjunction with the stimulation of osmotic flow (11).
Iontophoresis: Applications in Drug Delivery and Noninvasive Monitoring *
Published in Richard H. Guy, Jonathan Hadgraft, Transdermal Drug Delivery, 2002
M. Begoña Delgado-Charro, Richard H. Guy
Electroosmotic flow is a nonequilibrium process that may be analyzed by nonequilibrium thermodynamics (7). Briefly, electroosmosis is an electrokinetic phenomenon, the reciprocal of a “streaming current” (43), which corresponds to the flow of charge and volume that results from the application of a pressure gradient across a permselective membrane. In an iontophoretic experiment, a voltage is applied at a constant pressure that results in flows of charge and volume.
Application of iontophoresis in ophthalmic practice: an innovative strategy to deliver drugs into the eye
Published in Drug Delivery, 2023
Dong Wei, Ning Pu, Si-Yu Li, Yan-Ge Wang, Ye Tao
The direct-field effect, also called the Nernst-Planck effect, is based on the principle of ion movement caused by an applied electrical potential gradient. The ionized substances are attracted by direct-field effect to anode or the cathode depend on the charge. The direct-field effect, is the largest contributor to flux enhancement for small ions, but not the only one. Electroosmosis, also called the Electroosmotic flow, is the bulk fluid flow which occurs when a voltage difference is imposed across a charge membrane (Eljarrat-Binstock & Domb, 2006). The motion of the solvent can enhance the transport of ionic and neutral drugs. Electroosmosis is a dominant mechanism for the enhanced transport of large monovalent ionic during iontophoresis. Electropermeabilization is the alteration of a tissue barrier under the influence of an electric field that can increase the permeability of the tissue during and after iontophoresis (Li & Hao, 2018). The porosity of a membrane and the properties of the transport pathways in the membrane can be altered by the electric field. For neutral molecule, the electroosmotic flow is the major mechanism. Siva Ram Kiran Vaka et al found that the transport enhancement by iontophoresis was predominantly caused by the electrophoresis and/or electro-osmosis (Vaka et al., 2008).
Transdermal delivery via medical device technologies
Published in Expert Opinion on Drug Delivery, 2022
Shubhangi Shukla, Ryan H. Huston, Blake D. Cox, Abhay R. Satoskar, Roger J. Narayan
While drugs come in innumerable structural combinations, one way to classify them easily is using two main characteristics which provide unique advantages or challenges to their use, specifically drug permeability and drug solubility; hence, these two traits define the Biopharmaceutics Classification System taxonomy [111]. Iontophoresis has been shown to benefit many drugs with varying combinations of these traits; however, the most challenging drugs to deliver are those with low permeability and low solubility. Compared to water-soluble drugs, iontophoresis has not been thoroughly researched for use with lipophilic/hydrophobic or otherwise water-insoluble drugs. The current research has been largely focused on delivery of drugs via iontophoresis using water-based buffers and water-soluble ions; however, the principle of electroosmosis clearly supports the penetration of nonpolar or uncharged molecules as well [100]. In addition, creative drug formulations can enhance iontophoretic delivery by (a) placing drugs in liposomes or micelles; (b) mixing solutes with surfactants, cosolvents, or complexion solutes; or (c) substituting the solvent altogether [112].
Antibiotic uptake through porins located in the outer membrane of Gram-negative bacteria
Published in Expert Opinion on Drug Delivery, 2021
Ion current blockage itself as signal does not allow to distinguish binding from translocation [76]. The dwell or residence time reflects the time inside the channel constriction without giving a specific information on the side of exit. Application of an external force of controlled strength will shorten or prolong the residence time in the channel. Charged molecules will follow the external applied electric field whereas for neutral molecules we may benefit from electroosmosis [77–80]. What is electroosmosis? Charged amino acids exposed to the aqueous part in the channel do have a mobile counterion which can be dragged in the direction of an externally applied field. Most of the porin channels have an excess of cationic or anionic amino acids in the constriction zone; thus, an externally applied electric field would cause a net unidirectional flow originating from the excess surface charge. Molecules in the channel will be dragged with this flow and will shorten the residence times [79,80]. Thus, the effect of electroosmosis as an externally tuneable force can be used to probe for translocation. In a recent publication we could separate EOF from electrophoresis [80]. By comparing the residence times of molecules in the porin in the presence and absence of the barrier on the periplasmic side of the channel, one can identify true permeation events and identify molecules that reach the exit [81].