Hydrogel-Forming Microneedle Arrays Allow Detection of Drugs and Glucose <i>In Vivo</i>: Potential for Use in Diagnosis and Therapeutic Drug Monitoring - Fig 4

(A) Quantities of theophylline (μg) taken up in vitro by MN arrays 5, 30 and 60 min after insertion into dermatomed excised neonatal porcine skin mounted on modified Franz cells and bathed on the underside by phosphate buffered saline pH 7.4 thermostated to 37°C and containing defined concentrations of theophylline (Means ± SD, n = 6). (B) Quantity of theophylline (μg) taken up in vivo by MN arrays inserted into the skin on the back of Sprague Dawley® rats for 1 h after administering theophylline via oral gavage at doses of 5 and 10 mg/kg of rat’s body mass (Means ± SD, n = 6). (C) Exemplar chromatogram showing HPLC detection of theophylline following extraction from MN after insertion into the skin on a rat’s back for 1 h. Dose administered to rat via oral gavage = 10 mg/kg. (D) Exemplar chromatogram showing HPLC detection of theophylline from a plasma sample obtained from a rat via lateral vein tail puncture 1 h after administration of theophylline (10 mg/kg) via oral gavage.