Effect of Iontophoresis on the Intradermal Migration Rate of Medium Molecular Weight Drugs

Enhanced transdermal delivery of pioglitazone hydrochloride via conductive hydrogel microneedles combined with iontophoresis

The conventional oral administration of pioglitazone for Type II diabetes management is frequently compromised by hepatic first-pass metabolism and associated systemic adverse effects, necessitating the development of enhanced transdermal delivery approaches. This study developed a transdermal drug delivery system combining conductive hydrogel microneedles and iontophoresis to improve the transdermal delivery of pioglitazone hydrochloride (PIO) and its therapeutic efficacy in the treatment of type II diabetes. The microneedles, fabricated using poly(methyl vinyl ether-alt-maleic anhydride) as the main matrix material, exhibited excellent conductivity, mechanical strength, and high drug loading capacity. In vitro permeation experiments demonstrated that, when combined with iontophoresis at a current intensity of 0.5 mA, the cumulative permeation of PIO reached 238.1 ± 27.14 μg/cm2 within 48 h, significantly higher than that of the microneedle group alone. In a type II diabetic rat model, the microneedle-iontophoresis system displayed a significantly better hypoglycemic effect than the oral administration group, with a blood glucose reduction of 6.3 mmol/L on day 8, significantly higher than the 5.1 mmol/L reduction in the positive control group. Pharmacokinetic analysis indicated that the Tmax, T1/2, and mean residence time of the system were longer than those of oral administration, indicating sustained-release characteristics. Skin irritation tests revealed that the system caused only mild, transient skin irritation, with complete skin recovery within 24 h. In conclusion, conductive hydrogel microneedles combined with iontophoresis can effectively enhance PIO transdermal delivery, bioavailability, and therapeutic efficacy while also exhibiting good safety and potential clinical application value.

Enhanced Drug Skin Permeation by Azone-Mimicking Ionic Liquids: Effects of Fatty Acids Forming Ionic Liquids

Background/Objectives: Laurocapram (Azone) attracted attention 40 years ago as a compound with the highest skin-penetration-enhancing effect at that time; however, its development was shelved due to strong skin irritation. We had already prepared and tested an ante-enhancer (IL-Azone), an ionic liquid (IL) with a similar structure to Azone, consisting of ε-caprolactam and myristic acid, as an enhancer candidate that maintains the high skin-penetration-enhancing effect of Azone with low skin irritation. In the present study, fatty acids with different carbon numbers (caprylic acid: C8, capric acid: C10, lauric acid: C12, myristic acid: C14, and oleic acid: C18:1) were selected and used with ε-caprolactam to prepare various IL-Azones in the search for a more effective IL-Azone. Methods: Excised porcine skin was pretreated with each IL-Azone to assess the in vitro skin permeability of antipyrine (ANP) as a model penetrant. In addition, 1,3-butanediol was selected for the skin permeation test to confirm whether the effect of IL-Azone was due to fatty acids and if this effect differed depending on the concentration of IL-Azone applied. Results: The results obtained showed that C12 IL-Azone exerted the highest skin-penetration-enhancing effect, which was higher than Azone. On the other hand, many of the IL-Azones tested had a lower skin-penetration-enhancing effect. Conclusions: These results suggest the potential of C12 IL-Azone as a strong and useful penetration enhancer.

Design of Ionic Liquid Formulations with Azone-Mimic Structures for Enhanced Drug Skin Permeation

Although laurocapram (Azone) significantly enhances the skin permeation of drugs, its development was hindered by its skin irritation. We then developed an Azone-mimic ionic liquid (IL-Azone), composed of less irritating cationic ε-caprolactam and anionic myristic acid. IL-Azone dissociates to the original cation and anion in the presence of water in the formulation. We tried to select a formulation suitable for IL-Azone in the present study. Each formulation contained 5 % of either Azone or IL-Azone along with the model drug antipyrine, and skin permeation experiments of the drug were conducted. The results revealed that IL-Azone did not enhance skin permeation when combined with most formulations tested. However, a notable and rapid enhancement in skin permeation was observed when combined with white petrolatum. This effect could be attributed to the minimal water content in white petrolatum, which prevented IL-Azone degradation. Furthermore, its permeation-enhancing effects from IL-Azone in white petrolatum were more pronounced and rapid than Azone. The rapid onset observed with IL-Azone can be attributed to its degradation into its original components at the interface between the stratum corneum and the living epidermis, which results in a shorter lag time before achieving a steady-state concentration in the SC compared to Azone.

Remote-controllable dosage management through a wearable iontophoretic patch utilizing a cell phone

With regard to medical treatment through operations, remote control is possible, however, the area of remote-controllable drug treatment is yet to be established. In this study, a prototyped remote-controllable dosage management system that allows patients and caregivers to administer therapeutic drugs via an internet line without touching the dosage device or formulation was developed. This system consists of a transmitter (System A) located away from the patient, and a dosage device (System B) equipped with a receiver (B1), dosage management unit (B2), and a drug treatment unit (B3) that can be installed on the patient. Additionally, Bluetooth® is adopted to communicate from System A to System B. In the present study, System A was incorporated into a cell phone, and System B was a constant-current iontophoresis (IP) device, which was applied on excised pig skin. Sodium salt of betamethasone phosphate (BP^-Na⁺) was selected as a model drug, and the in vitro skin permeation of BP^- was evaluated. As a result, by transmitting the administration information incorporated in System A through B1 to B2, the optimal current was passed between the IP electrodes in B3, and the skin permeation of BP^- was obtained by remote control. That is, the skin permeation of BP^- was obtained by the current flowing from the IP device. The permeation amount decreased when the voltage load was stopped. These results suggested that remote control from System A enables dosing management of bioactive substances from dosage devices applied on the skin, intracutaneously, or subcutaneously without being near the patient. Although various trials are still required to complete the remote-controlled system, the patient does not have to go to the hospital except to take injections. Such drug administrations would lead to decreased medical expenses and increased quality of life for patients.