Microneedles have been developed in the past few years as a new means of transdermal
drug delivery. They indeed present many advantages compared to injections using hypodermic needles
(reduced risk of contamination and epidermic reactions), but mostly bring comfort and compliance
to patients. Microneedles may be plain, opening pathways for medications to dissolve into the
skin, or hollow, allowing fluid to actually enter the dermis or the hypodermis. This review focuses on
the latter type of microneedles and two issues with their application: first, ensuring correct insertion
into the skin (controlled and repeatable insertion depth, mainly); and second, ensuring correct fluid delivery to the dermis
(controlled infusion rate). This paper thus focuses on recently published patents for hollow microneedle applicators-i.e.,
microneedles applicators that allow fluid delivery to the skin. Descriptions are given of several of the most relevant patents
concerning this. The benefits and drawbacks of the different solutions are also described.
Keywords: Hollow microneedles, microneedle applicators, microneedle fluid delivery, microneedle insertion devices, selfinjection,
transdermal drug delivery.
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