ABSTRACT
OBJECTIVE: To prepare dissolving microneedles using Gantrez S-97 and PVPk30 as composite matrix materials to accelerate the delivery of poorly water soluble drugs and study the preparation, appearance, mechanical properties, intradermal solubility, drug efficacy and crystallization behavior of dissolving microneedles. METHODS: Using polydimethylsiloxane(PDMS) as the negative mode, microneedles were prepared by the reverse casting method. SEM was used to observe the morphological appearance of the microneedles. The mechanical properties of the microneedles were investigated by texture analyzer and histological sections. Delivery of lidocaine was characterized by intradermal dissolution and pharmacodynamics. Crystallization behavior of lidocaine was characterized by DSC. RESULTS: Lidocaine dissolving microneedles had good needle shape and possessed sufficient mechanical strength to penetrate into the skin. The microneedles could dissolve in the dermis within 3 min and retain anesthetic effect, and the drug existed in amorphous form in the microneedles. CONCLUSION: Cosolvent preparation of dissolving microneedles has potential for promoting the delivery of poorly water soluble drugs.
ABSTRACT
As a novel transdermal drug delivery technology,microneedles has some advantages including high efficiency and safety over other drug administration routes. The skin puncture performance is the premise and key for microneedles to deliver drugs. Based on the mechanical strength of the microneedles and the puncture effect of the skin, this review summarized the current evaluation methods of puncture performance. These methods were described here such as fracture strength measurement, pressure-displacement performance testing, organic dye staining, transepidermal water loss, electrical impedance method, histological sections, confocal microscopy and optical coherence tomography. The scope of application, advantages and disadvantages of various methods were analyzed, which provide references for other researchers to choose suitable evaluation method of microneedles puncture performance.
ABSTRACT
Microneedles is an efficient, safe and novel transdermal drug delivery technology that has attracted much attention in recent decades. Microneedles could break through the skin's stratum corneum barrier and have an especially significant effect on the transdermal delivery of water-soluble small molecules and biological macromolecules. In this paper, a rapid onset local anesthetic preparation of lidocaine hydrochloride was prepared based on dissolving microneedles, and related quality evaluations were carried out. The key quality indicators of prepared lidocaine hydrochloride dissolving microneedles such as drug loading amount, appearance morphology, mechanical properties, skin penetration performance, in vitro dissolution performance and local anesthetic efficacy were investigated with HPLC, SEM, texture analyzer, organic staining, histological section, in vitro dissolution test and pharmacodynamics experiments respectively. The drug loading of the dissolving microneedles array reached 68.19 ±1.55 mg, and the needle tip contained 3.57 ±0.21 mg. The microneedles has good needle shape and sufficient mechanical strength to penetrate into the skin, which is a prerequisite for the successful administration of the preparation. The in vitro dissolution time was 28.28 ±1.12 s. When applied to guinea pig back acupuncture model which was modified by guinea pig intradermal papules model, although the efficacy maintenance time was shorter than that of compound lidocaine cream, dissolving microneedles can be activated within 1 min, which was much faster than compound lidocaine cream. It is possible to increase the duration of drug efficacy by increasing the density of microneedles and preparing microneedles for sustained and controlled release in future studies. Lidocaine hydrochloride dissolving microneedles and its evaluation methods for local anesthesia were established systematically here for the first time. The rapid effect of anesthesia with lidocaine hydrochloride dissolving microneedles on the skin was worthy of further investigation.