This study showed that drug-coated PLLA (Poly
(L-lactide)) microneedle arrays can induce rapid and painless
local anesthesia. Microneedle arrays were fabricated using a
micro-molding technique, and the needle tips were coated
with 290.6 ± 45.9 μg of lidocaine, the most widely used local
anesthetic worldwide. A dip-coating device was newly de-
signed for the coating step using an optimized coating formu-
lation. Lidocaine coated on the arrays was released rapidly
into PBS within 2 min, and its stability in storage lasted
3 weeks at 4, 25, and 37°C. Furthermore, the microneedle
arrays showed consistent in vitro skin penetration and deliv-
ered 200.8 ± 43.9, 224.2 ± 39.3, and 244.1 ± 19.6 μg of
lidocaine into the skin 1, 2, and 5 min after application with
a high delivery efficiency of 69, 77, and 84%. Compared to a
commercially available topical anesthetic EMLA® cream,
a 22.0, 13.6, and 14.0-fold higher amount of lidocaine
was delivered into the skin. Note, in vitro skin permeation
of Lidocaine was also notably enhanced by a 2-min-
application of the lidocaine-coated microneedle arrays.
Altogether, these results suggest that the biocompatible
lidocaine-coated PLLA microneedle arrays could provide
significantly rapid local anesthesia in a painless manner
without any of the issues from topical applications or
hypodermic injections of local anesthetics.

• Drug-coated microneedles for rapid and painless local anesthesia