MagnetophoresisMagnetophoresisis technique where magnetic field causes the drug permeation enhancement ofdiamagnetic drugs across SC layer e.g.
salbutamol sulfate and benzoic acid bymechanism of magnetokinesis. Since most of the drugs are not magnetic innature, drug embedded magnetic nanoparticles can be used as drug carrier toenhance transdermal drug delivery. In magnetophoresis pulsed electromagneticfield is used which cause transient pores formation and altering the structuresof keratinocytes by diamagnetic repulsion. Cheng et al.investigated the TDD of thotrexate-loaded silkfibroin magnetic nanoparticles and used stationary magnetic field and analternating magnetic field.
Synergetic effect (messaging effect) was observedon the skin with increased permeation flux enhacment under stationary magneticfield and enhanced and effective drug permeation under alternating magneticfield in invitro. Attenuated total reflection FTIR analysis revealed thatalternating magnetic field changes the gel like ordered SC lipid bilayerstructure to more lipid crystalline state which leads to increased lipidfluidity of SC layer and thus enhanced permeation. Recent studies alsoestablished that the messaging action causes much deeper penetration and henceenhanced drug permeation though transfollicular route.During messaging, physiological hair movement is stimulated and it act as apump which pushes nanoparticles deep into hair follicles. Murthy et al. (2010) also reported thatoctanol/water partition coefficient of drugs also increase on exposure to themagnetic field. Magnetophoresis offers advantages like 1) there is noimplication of magnetic field on the skin ; 2) it can be easily moulded intodifferent shape and sizes 3) it does not require prior charging/ power; 4) itcan be used safely and no sterility issues are there.
Murthy et al (2010) havefabricated a cutaneous patch of lidocaine where neodymium of known equalstrength were arranged and anchored in parallel on backing membrane and ontothis membrane a thin film of HPMC gel of lidocaine hydrochloride was spread andwhole system was then fixed onto a adhesive 3m form tape. Magnetophoresis isrelatively more economical to other physical enhancement systems and muchsafer.