title: Dissolving microneedles for enhanced local delivery of capsaicin to rat skin tissue.
abstract: Capsaicin-loaded dissolving microneedles (DMNs) were prepared to investigate the analgesic effect of capsaicin on the skin. The dimensions of each microneedle (MN) were as follows: diameter of the basement, 17 mm; length, 500 μm; and width, 300 μm. The average capsaicin content in the DMNs loaded with a low and high dose of capsaicin was 8.8 ± 0.5 mg and 12.5 ± 0.4 mg. Almost all the capsaicin, 99.3 ± 4.1% and 99.7 ± 2.2% for low-dose and high-dose DMNs were released within 20 min. High amounts of capsaicin were recovered with 102.8 ± 0.1% of capsaicin after storage at 23 °C for 90 days. The pharmacological activity of capsaicin DMNs was compared to that of capsaicin cream as a positive control, by measuring the idiospasm of depilated rat skin. The time required to achieve 50% idiospasm suppression was 26.3 ± 1.9 min and 53.0 ± 2.3 min for low-dose and high-dose DMNs. A pharmacokinetic study showed high tissue capsaicin levels of 660.2 ± 120.6 and 1805.3 ± 218.1 μg/g wet weight for low-dose and high-dose DMNs at 5 min after administration. The results suggest that DMNs could exert a rapid local analgesic action on the skin.
authors.affiliation: a Department of Pharmacokinetics , Kyoto Pharmaceutical University , Yamashina-ku , Kyoto , Japan.
authors.forename: Yukako
authors.initials: Y
authors.lastname: Ito
authors.affiliation: a Department of Pharmacokinetics , Kyoto Pharmaceutical University , Yamashina-ku , Kyoto , Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Kobuchi
authors.affiliation: a Department of Pharmacokinetics , Kyoto Pharmaceutical University , Yamashina-ku , Kyoto , Japan.
authors.forename: Genta
authors.initials: G
authors.lastname: Inoue
authors.affiliation: a Department of Pharmacokinetics , Kyoto Pharmaceutical University , Yamashina-ku , Kyoto , Japan.
authors.forename: Eisaku
authors.initials: E
authors.lastname: Kakumu
authors.affiliation: a Department of Pharmacokinetics , Kyoto Pharmaceutical University , Yamashina-ku , Kyoto , Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Aoki
authors.affiliation: a Department of Pharmacokinetics , Kyoto Pharmaceutical University , Yamashina-ku , Kyoto , Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakaeda
authors.affiliation: b BioSerenTach Inc , Nakagyo-ku , Kyoto , Japan.
authors.forename: Kanji
authors.initials: K
authors.lastname: Takada
mesh_terms: D000818:Animals; D002211:Capsaicin / Q000008:administration & dosage* / Q000493:pharmacokinetics; D004305:Dose-Response Relationship, Drug; D008297:Male; D009339:Needles; D051381:Rats; D017208:Rats, Wistar; D012867:Skin / Q000378:metabolism*
chemical_list: D002211:Capsaicin
keywords: Capsaicin; dissolving microneedles; idiospasm; percutaneous administration; rat; short onset time