Studies on local anesthetic lidocaine hydrochloride delivery via photo-triggered implantable polymeric microneedles as a patient-controlled transdermal analgesia system

Advances in the use of local anesthetic extended-release systems in pain management

Pain management remains among the most common and largely unmet clinical problems today. Local anesthetics play an indispensable role in pain management. The main limitation of traditional local anesthetics is the limited duration of a single injection. To address this problem, catheters are often placed or combined with other drugs in clinical practice to increase the time that local anesthetics act. However, this method does not meet the needs of clinical analgesics. Therefore, many researchers have worked to develop local anesthetic extended-release types that can be administered in a single dose. In recent years, drug extended-release systems have emerged dramatically due to their long duration and efficacy, providing more possibilities for the application of local anesthetics. This paper summarizes the types of local anesthetic drug delivery systems and their clinical applications, discusses them in the context of relevant studies on local anesthetics, and provides a summary and outlook on the development of local anesthetic extended-release agents.

Advances of Smart Stimulus-Responsive Microneedles in Cancer Treatment

Microneedles (MNs) have emerged as a highly promising technology for delivering drugs via the skin. They provide several benefits, including high drug bioavailability, non-invasiveness, painlessness, and high safety. Traditional strategies for intravenous delivery of anti-tumor drugs have risks of systemic toxicity and easy development of drug resistance, while MN technology facilitates precise delivery and on-demand release of drugs in local tissues. In addition, by further combining with stimulus-responsive materials, the construction of smart stimulus-responsive MNs can be achieved, which can respond to specific physical/chemical stimuli from the internal or external environment, thereby further improving the accuracy of tumor treatment and reducing toxicity to surrounding tissues/cells. This review systematically summarizes the classification, materials, and reaction mechanisms of stimulus-responsive MNs, outlines the benefits and challenges of various types of MNs, and details their application and latest progress in cancer treatment. Finally, the development prospects of smart MNs in tumor treatment are also discussed, bringing inspiration for future precision treatment of tumors.

Roller microneedles transdermal delivery of compound lidocaine cream for enhancing the analgesic effect: A randomized self-controlled trial

OBJECTIVE

The purpose of this article is to investigate whether the percutaneous delivery of compound lidocaine cream by roller microneedles can shorten the minimal effective onset time of anesthesia, enhance the intensity of anesthesia and prolong the analgesic time, so as to provide a theoretical basis for exploring a comfortable, safe and effective anesthesia method for photoelectric cosmetic surgery.

METHODS

A total of 90 healthy volunteers, including 18 male and 72 female, met the criteria and were enrolled in the study from December 2020 to September 2021 in Department of Plastic and Burn Surgery of the First Affiliated Hospital of Chongqing Medical University. This study adopted a two-factor randomized block design of 3 (anesthesia time on the test side: 30, 45, 60 min) × 2 (the test side: the left and right side), and the subjects were divided into group A (n = 30), group B (n = 30), and group C (n = 30). On the test side, the compound lidocaine cream was used for topic anesthesia for 10 min, then the roller microneedle was used to roll on the treatment area, compound lidocaine cream was appropriately supplemented, and the topic anesthesia was kept continued for 20 min (group A), 35 min (group B), and 50 min (group C), respectively. The mirrorsymmetrical area of the test side of the three groups was the control side, and the compound lidocaine cream was used for topic anesthesia for 60 min. Photoelectric therapy was performed after anesthesia was completed. The analgesic effect of the subjects on both sides was comprehensively compared; the scores were obtained using the Kuttner Facial Expression Scale, the Frankl Treatment Compliance Scale, the Houpt Behavior Scale, and the Visual Analog Scale (VAS); the satisfaction with anesthesia was investigated. Before and after treatment the skin temperature, color and adverse reactions of the subjects were recorded.

RESULTS

Comparing both sides of the same group, there was no significant difference in terms of the comprehensive evaluation, intraoperative comfort, tolerance, cooperation, pain or satisfaction between the 30-min test side and the routine anesthesia side in group A; the comprehensive evaluation, intraoperative tolerance, cooperation degree, pain degree and satisfaction evaluation of the subjects on the 45-min test side in group B were significantly better than those on the control side; the comprehensive evaluation, intraoperative comfort, tolerance, cooperation, pain and satisfaction of the subjects on the 60-min test side in group C were significantly better than those on the control side. Comparing groups on the control side, there was no significant difference in the comprehensive evaluation, intraoperative comfort, tolerance, cooperation, pain or satisfaction between the three groups of subjects on the control side. Comparing the three groups on the test side, with the prolongation of compound lidocaine cream indwelling time, the subjects' comprehensive evaluation, comfort and pain degree were significantly improved. There was no significant difference in postoperative bruising, swelling, pain, discoloration, redness, or tenderness between the test side and the control side.

CONCLUSION

The percutaneous delivery of compound lidocaine cream by roller microneedles can not only shorten the effective time of anesthesia, but also has a good analgesic effect without obvious adverse reactions.

Lidosomes: Innovative Vesicular Systems Prepared from Lidocaine Surfadrug

Lidocaine is a local anaesthetic drug with an amphiphilic structure able to self-associate, under certain conditions, in molecular aggregates playing the role of both carrier and drug. The aim of this study was to determine the optimal conditions for obtaining vesicular carriers, called lidosomes. The new formulations were obtained using both lidocaine and lidocaine hydrochloride and different hydration medias (distilled water, acid, and basic aqueous solution). Lidosomes formulations were characterized in terms of size, ζ-potential, drug retained, stability formulation, and ex vivo permeation profile. Moreover, lidosomes were incorporated in two different gel structures: one based on carboxymethylcellulose and one based on pluronic F-127 to achieve suitable properties for a topical application. Results obtained showed that lidocaine showed a better performance to aggregate in vesicular carriers in respect to hydrochloride form. Consequently, only formulations comprised of lidocaine were studied in terms of skin permeation performance and as carriers of another model drug, capsaicin, for a potential combined therapy. Lidocaine, when in form of vesicular aggregates, acted as percutaneous permeation enhancer showing better permeation profiles with respect to drug solutions. Moreover, lidosomes created a significant drug depot into the skin from which the drug was available for a prolonged time, a suitable feature for a successful local therapy.