Drug administration via skin is painless, needle-free, undergoing less drug degradation, simple in administration and allows rapid withdrawal of therapy when adverse effects develop, when compared to oral and injection routes [Citation1]. However, the daily dose of a drug that can be delivered across the skin is small (5–10 mg) [Citation2]. Passive (chemical formulation) and active (electric, laser, microneedle, ultrasound) methods have been devised to make skin porous and improve drug penetration through skin with the aim to increase drug retention in skin and/or diffusion into blood for treatment of skin-related diseases or others [Citation1,Citation3]. Electrical (iontophoresis) and low-frequency ultrasound methods have been clinically approved for local/topical anesthesia [Citation1]. High-frequency ultrasound method is used clinically to increase steroids and anti-inflammatory drugs administration via skin. Thermal and laser methods have been tested in a number of human clinical trials.
Lately, microwave is examined for its potential to aid drug administration through skin [Citation3–Citation5]. The use of microwave technology in medical practice is no alien to the practitioners. The microwave has been developed to treat cancer specifically, via its heating effects and ability to raise the cancer cells’ sensitivity to chemo and radiation therapies [Citation1]. The development of microwave for drug administration application via skin is a recent advancement. Unlike medical practice (45–100 W), low-intensity microwave (1 mW) will be adopted. Its use can be long or short term as a function of disease type, and operated by patients instead of medical practitioners. The drug administration is mediated without skin heating, unlike electrical, laser, or ultrasound technique [Citation1,Citation3]. There is no risk of electrical shock and tissue damage.
Pre-treatment of skin by microwave followed by the application of nanomedicine, in the form of ethanol-rich or polysaccharide-rich nanocarriers, is met with success at laboratory [Citation4,Citation5] and pre-clinical levels (unpublished data) in term of skin drug retention (500–600 folds of neat 5-fluorouracil) and drug permeation into blood stream (3 folds of neat 5-fluorouracil). The future of applying microwave as skin penetration enhancer for drugs formulated as nanomedicine is optimistic. Evidence-based supports through clinical trials and regulatory assessment are required in the immediate future for its translation into practice. With reference to skin drug delivery, the safety of microwave as the penetration enhancer has been evaluated in animal model [Citation3]. The acute histological changes of lung, liver and kidney had been examined and were found to experience insignificant alterations under the influence of microwave. More studies are however required to examine the molecular biological details of various organs and tissues, over short and long term usage of microwave.
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The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
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References
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