Advances in Transdermal Drug Delivery Systems: A Bibliometric and Patent Analysis

Transdermal drug delivery systems have become an intriguing research topic in healthcare technology and one of the most frequently developed pharmaceutical products in the global market. In recent years, researchers and pharmaceutical companies have made significant progress in developing new solutions in the field. This study sheds light on current trends, collaboration patterns, research hotspots, and emerging frontiers of transdermal drug delivery. Herein, a bibliometric and patent analysis of data recovered from Scopus and The Lens databases, respectively, is reported over the last 20 years. From 2000 to 2022, the annual global publications increased from 131 in 2000 to 659 in 2022. Researchers in the United States, China, and India produced the highest number of publications. Likewise, most patent applications have been filed in the USA, China, and Europe. The recovered patents are 7275, grouped into 2997 patent families, of which 314 were granted. This study could support the work of decision-makers, scientific managers, or scientists to create new business opportunities or save money, time, and intellectual capital, thereby defining when a research or technology project should be a priority or not.

Mathematical modelling of microneedle-mediated transdermal delivery of drug nanocarriers into skin tissue and circulatory system

Microneedle-mediated transdermal delivery using nanocarriers can successfully overcome the barrier of the stratum corneum and protect drugs from elimination in skin tissues. However, the effectiveness of drug delivery to different layers of skin tissues and the circulatory system varies considerably, subject to the properties of the drug delivery system and delivery regime. How to maximise delivery outcomes remains unclear. In this study, mathematical modelling is employed to investigate this transdermal delivery under various conditions, using the skin model that is reconstructed based on the realistic skin anatomical structure. Treatment efficacy is evaluated in terms of drug exposure over time. The modelling results demonstrate the complex dependence of drug accumulation and distribution on the nanocarrier properties, microneedle properties and environment in different skin layers and blood. Specifically, delivery outcomes in the entire skin and blood can be improved by increasing the loading dose and reducing microneedle spacing. However, several parameters need to be optimised with respect to the specific location of the target site in the tissue for better treatment; these include the drug release rate, nanocarrier diffusivity in microneedle and skin tissue, nanocarrier transvascular permeability, nanocarrier partition coefficient between tissue and microneedle, microneedle length, wind speed and relative humidity. The delivery is less sensitive to the diffusivity and physical degradation rate of free drugs in microneedle, and their partition coefficient between tissue and microneedle. Results obtained from this study can be used to improve the design of the microneedle-nanocarrier combined drug delivery system and delivery regime.

Efficacy of Transdermal Ketoprofen Patch in Comparison to Transdermal Diclofenac Patch in Postoperative Analgesia for Orthodontic Extractions: A Randomized Split-Mouth Study

Introduction Non-steroidal anti-inflammatory drugs (NSAIDs) are the most prescribed analgesics for controlling post-exodontia pain, administered by various routes. The transdermal route possesses the advantages of providing sustained release of the drug, being non-invasive, bypassing first-pass metabolism, and eliminating gastrointestinal adverse effects. This study compared the analgesic efficacy of diclofenac 200 mg and ketoprofen 30 mg transdermal patches for post-orthodontic exodontia pain. Materials and methods Thirty patients who underwent orthodontic bilateral maxillary and/or mandibular premolar extractions under local anaesthesia were included in the study. Each patient received single transdermal diclofenac 200 mg patch and single transdermal ketoprofen 30 mg patch on the outer, ipsilateral upper arm immediately post-extraction in the two appointments in random order. The pain score was recorded every second hourly for the first 24 hours postoperatively using a visual analog scale (VAS). The requirement of rescue analgesics at various time points and the total number of rescue analgesics taken in the first 24 hours postoperatively were noted. Any allergic reaction to the transdermal patches was also recorded. Results The analgesic efficacy of the two transdermal patches at any given time point in 24 hours by Mann-Whitney U test showed no statistically significant (p<0.05) difference. An overall intragroup statistically significant difference (p<0.05), by Wilcoxon matched pairs test, was found by comparison of VAS pain scores at different time points to that at 0-2 hours after application of transdermal ketoprofen and diclofenac patches, respectively. The mean maximum pain intensity was slightly lower for ketoprofen (2.33) than diclofenac (2.60) transdermal patch. Patients consumed the rescue analgesic within the first 12 hours postoperatively, with the mean value of the total number of rescue analgesics taken with ketoprofen transdermal patch (0.23) slightly lower than diclofenac transdermal patch (0.27) application. Conclusion Ketoprofen and diclofenac transdermal patches provide similar analgesia post orthodontic extraction. The patients required rescue analgesics only during the initial hours of the postoperative follow-up period.

Microneedle-Mediated Transdermal Delivery of Biopharmaceuticals

Transdermal delivery provides numerous benefits over conventional routes of administration. However, this strategy is generally limited to a few molecules with specific physicochemical properties (low molecular weight, high potency, and moderate lipophilicity) due to the barrier function of the stratum corneum layer. Researchers have developed several physical enhancement techniques to expand the applications of the transdermal field; among these, microneedle technology has recently emerged as a promising platform to deliver therapeutic agents of any size into and across the skin. Typically, hydrophilic biomolecules cannot penetrate the skin by passive diffusion. Microneedle insertion disrupts skin integrity and compromises its protective function, thus creating pathways (microchannels) for enhanced permeation of macromolecules. Microneedles not only improve stability but also enhance skin delivery of various biomolecules. Academic institutions and industrial companies have invested substantial resources in the development of microneedle systems for biopharmaceutical delivery. This review article summarizes the most recent research to provide a comprehensive discussion about microneedle-mediated delivery of macromolecules, covering various topics from the introduction of the skin, transdermal delivery, microneedles, and biopharmaceuticals (current status, conventional administration, and stability issues), to different microneedle types, clinical trials, safety and acceptability of microneedles, manufacturing and regulatory issues, and the future of microneedle technology.

Development of Bioadhesive Transdermal Patches of Bupivacaine for the Enhancement of Anaesthetic Effect: Study in Rat Model

The topical route for local anaesthesia including ointments and creams can be easily washed off by wetting agents or with contact or movement. The goal and objective of the present study was to develop and formulate a transdermal patch for local anaesthesia. These patches were formulated by solvent casting method by the use of Hydroxypropyl Methylcellulose (HPMC) polymer, different enhancers, and vasoconstrictor which is the key ingredient for enhancing aesthetic activity. Formulated patches were evaluated for the physical and physicochemical parameters like moisture content, moisture uptake, folding endurance, water vapour permeability, drug content, and drug release, and in vivo study was done on rats. Amongst all the formulations, F7 was considered the ideal formulation which is the combination of HPMC polymer, polyoxyethylene 2-oleyl ether as an enhancer, and vasoconstrictor Tetrahydrozoline. For in vivo testing Tail flick method was applied and the effect of anaesthesia was maximum as compared to other formulations. In comparison to the control formulation, there was a 2.34-fold increase in aesthetic activity. When compared to the control formulation, the F7 formulation exhibited improved and longer efficacy. A transdermal bupivacaine patch incorporating a penetration enhancer and a vasoconstrictor could be created to improve the local cosmetic effects of bupivacaine.

Fabrication and Characterizations of Pharmaceutical Emulgel Co-Loaded with Naproxen-Eugenol for Improved Analgesic and Anti-Inflammatory Effects

The aim of this study was to fabricate and characterize a pharmaceutical emulgel co-loaded with naproxen/eugenol for transdermal delivery to improve the analgesic and anti-inflammatory effects and to eliminate GIT adverse reactions. Emulgel was prepared using a slow emulsification method and evaluated for physical appearance, thermodynamic stability, viscosity, pH, spreadability, extrudability, in-vitro drug release, drug content, ex-vivo permeation, drug retention studies and in-vivo studies. The emulgel exhibited good physical attributes, being thermodynamically stable with no phase separation, having excellent homogeneity, and pH 5.5 to 6.5. Slight changes in viscosity, spreadability and extrudability with respect to high temperature were observed (p > 0.05). The drug content was 96.69 ± 1.18% and 97.24 ± 1.27% for naproxen and eugenol, respectively. The maximum release of naproxen after 12 h was 85.14 ± 1.11%, whereas eugenol was 86.67 ± 1.23% from emulgel following anomalous non-Fickian mechanism. The maximum % permeation of naproxen across skin was 78.5 ± 1.30, whereas maximum % permeation of eugenol was 83.7 ± 1.33 after 12 h. The skin retention of eugenol and naproxen was 8.52 ± 0.22% and 6.98 ± 0.24%, respectively. The optimized emulgel inhibited the carrageenan induced paw edema. The pain reaction times of optimized emulgel and standard marketed product (Voltral®) were 11.16 ± 0.17 and 10.36 ± 0.47, respectively, with no statistically significant difference (p > 0.05). This study concluded that transdermal delivery of naproxen-eugenol emulgel synergized the anti-inflammatory and analgesic effects of naproxen and eugenol.

Beneath the Skin: A Review of Current Trends and Future Prospects of Transdermal Drug Delivery Systems

The ideal drug delivery system has a bioavailability comparable to parenteral dosage forms but is as convenient and easy to use for the patient as oral solid dosage forms. In recent years, there has been increased interest in transdermal drug delivery (TDD) as a non-invasive delivery approach that is generally regarded as being easy to administer to more vulnerable age groups, such as paediatric and geriatric patients, while avoiding certain bioavailability concerns that arise from oral drug delivery due to poor absorbability and metabolism concerns. However, despite its many merits, TDD remains restricted to a select few drugs. The physiology of the skin poses a barrier against the feasible delivery of many drugs, limiting its applicability to only those drugs that possess physicochemical properties allowing them to be successfully delivered transdermally. Several techniques have been developed to enhance the transdermal permeability of drugs. Both chemical (e.g., thermal and mechanical) and passive (vesicle, nanoparticle, nanoemulsion, solid dispersion, and nanocrystal) techniques have been investigated to enhance the permeability of drug substances across the skin. Furthermore, hybrid approaches combining chemical penetration enhancement technologies with physical technologies are being intensively researched to improve the skin permeation of drug substances. This review aims to summarize recent trends in TDD approaches and discuss the merits and drawbacks of the various chemical, physical, and hybrid approaches currently being investigated for improving drug permeability across the skin.

Comparison of Pain Scale, Hemodynamics, and Side Effects of Percutaneous and Intravenous Fentanyl in Post Sectio Caesaria Patients at Bunda Hospital

This is novel research about comparison pain scale, hemodynamics, and side effects of percutaneous and intravenous fentanyl in post sectio cesarean patients. Sectio cesarean is a method of delivering a fetus through an incision in the abdominal wall (laparotomy) and the uterus wall. This method induces pain in the incision, so patients feel complicated or afraid to mobilize. Fentanyl is one of the opioid analgesics, which is the main choice in section caesarian surgery because safe for breastfeeding, is more potent than morphine, and acts as balanced anesthesia—comparing the use of percutaneous fentanyl with intravenous fentanyl with pain scale parameters, hemodynamics, and side effects in sectio caesarian patients at Bunda Mother and Child Hospital Jakarta. Before conducting this research, an observational study first makes an ethical approval. Data were taken prospectively and collected simultaneously to compare percutaneous and intravenous fentanyl performed on post sectio cesarean patients with the physical status of the American Society of Anesthesiologists (ASA) I–II at Bunda Mother and Child Hospital Jakarta from September to November 2020. Comparative data observed were pain scale parameters, hemodynamics, and side effects after percutaneous fentanyl therapy or intravenous fentanyl therapy. Data were processed using SPSS 22 version and Microsoft Excell 2016. In conclusion, intravenous fentanyl is more effective in reducing pain scale and has more minor side effects than percutaneous fentanyl. There is no significant difference in hemodynamic parameters (p-value >0.05).

Development and Evaluation of Novel Water-Based Drug-in-Adhesive Patches for the Transdermal Delivery of Ketoprofen

The objective of this study was to develop novel water-based drug-in-adhesive pressure-sensitive adhesives (PSAs) patches for the transdermal delivery of ketoprofen, employing poly(N-vinylpyrrolidone-co-acrylic acid) copolymer (PVPAA) and poly(methyl vinyl ether-alt-maleic anhydride) (PMVEMA) as the main components. The polymers were crosslinked with tartaric acid and dihydroxyaluminium aminoacetate using various polymer ratios. Ketoprofen was incorporated into the PVPAA/PMVEMA PSAs during the patch preparation. The physicochemical properties, adhesive properties, drug content, release profile, and skin permeation of the patches were examined. Moreover, the in vivo skin irritation and skin adhesion performance in human volunteers were evaluated. The patches prepared at a weight ratio of PVPAA/PMVEMA of 1:1 presented the highest tacking strength, with desirable peeling characteristics. The ketoprofen-loaded PVPAA/PMVEMA patches exhibited superior adhesive properties, compared to the commercial patches, because the former showed an appropriate crosslinking and hydrating status with the aid of a metal coordination complex. Besides, the permeated flux of ketoprofen through the porcine skin of the ketoprofen-loaded PVPAA/PMVEMA patches (4.77 ± 1.00 µg/cm²/h) was comparable to that of the commercial patch (4.33 ± 0.80 µg/cm²/h). In human studies, the PVPAA/PMVEMA patches exhibited a better skin adhesion performance, compared with the commercial patches, without skin irritation. In addition, the patches were stable for 6 months. Therefore, these novel water-based PSAs may be a potential adhesive for preparing drug-in-adhesive patches.

Characteristics of Analgesic Patch Formulations

Topical and transdermal formulations are a common means of pharmaceutical drug delivery. If a drug is able to penetrate transcutaneously, the skin is an ideal site for the delivery of medications for both local (topical) and systemic (transdermal) effects. The administration of analgesics through the skin poses several potential advantages to those administered orally including compliance, the ability to deliver a drug to a peripheral target site and more stable and sustained plasma levels. One method of drug delivery is with the use of patch formulations - also known as patch systems. Typically, transdermal patches deliver medications intended to reach the systemic circulation, whereas topical patches are designed to keep medication localized for targeted delivery in proximity to the application site. There are a variety of technologies and materials utilized in patches, as well as penetration and formulation enhancers that ultimately affect the performance, efficacy and safety of the patch system. The degree of adherence to the skin is also of critical importance in drug delivery. Patches that lift up or fall off before the prescribed time period may represent a therapeutic failure and must be replaced, increasing patch utilization and cost to the healthcare system or to the patient. The added risk from accidental exposure makes poor patch adhesion a safety issue as well. A variety of analgesics are currently available as patch formulations including local anesthetics, capsaicin, nonsteroidal anti-inflammatory drugs and opioids. This review will highlight each of those patch delivery systems and introduce newer patch technologies that lend towards improved adhesion and compliance. Understanding the designs, limitations and benefits of patch systems will allow clinicians to select between these therapies when appropriate for their patients.

Facile design and development of photoluminescent graphene quantum dots grafted dextran/glycol-polymeric hydrogel for thermoresponsive triggered delivery of buprenorphine on pain management in tissue implantation

A novel nano-formulations of biocompatible, biodegradable and thermo-responsive graphene quantum dots (GQDs) loaded dextran/poly(N-isopropylacrylamide) (Dex/PNIPAM) copolymeric matrix was synthesized and analyzed the materials characterization, sustained drug delivery system, tissue feasibility in the tissue implantation site. This research report was aimed to grafting and functionalizing thermo-responsive (Dex/PNIPAM) copolymeric composite with presence of graphene quantum dots to achieve thermal responsive drug delivery (TrDD) with no harm effect in the implantation site. The synthesized GQD by using ionic liquid were evaluated by spectroscopic (DLS, PL, XRD and Raman spectroscopy) and Transmission electron microscopic analysis (TEM). The ultra-small GQDs loaded Dex/PNIPAM and was appeared to be asymmetric and open uniform porous structure, which can be significantly favorable for cell uptake and greatly influenced to be an effective drug carrier into the cellular compartment with good fluid flow. The PNIPAM polymeric composite were exhibited sustained and enhanced drug release percentages with increasing temperature at above low critical solution temperature (LCST) is 39 °C comparable to the cumulative drug release profile of below LCST (32 °C), which demonstrated that thermo-responsive polymer was played a significant role in the delivery system. The treated group of GQDs-Dex/PNIPAM was observed that no inflammation and shows noteworthy stromal cell infiltration, demonstrating that the synthesized drug carriers did not harm to the nerves and tissues and only was responsible for the pain management.

Rosmarinic acid-loaded electrospun nanofibers: In vitro release kinetic study and bioactivity assessment

This study seeks to develop a nanofibrous matrix containing rosmarinic acid (RosA), an herbal non-steroidal anti-inflammatory and antioxidant drug with low water solubility, for drug delivery applications. Neat and two types of RosA-loaded cellulose acetate (CA) mats varying in the initial content of RosA were electrospun. Microstructure of nanofibers, chemistry and physical state of RosA in nanofibers, RosA loading efficiency and RosA release in acetate buffer were investigated. To evaluate bioactivity of RosA-loaded nanofibers, their ability to inhibit protein denaturation was assayed as an indicator of anti-inflammatory properties and their antioxidant activity was determined by radical scavenging assay. The indirect cytotoxicity assay was used to find if there is a cytotoxic response to nanofibers. The homogeneous distribution of the drug within nanofibers through electrospinning led to high loading efficiency, low burst release and prolonged release of a large percentage of RosA over a period of 64h following Fickian diffusion mechanism. Nanofibers with higher RosA content exhibited anti-inflammatory activity comparable to ibuprofen, and higher antioxidant activity compared to nanofibers with lower RosA content. Additionally, extracts from nanofibers did not give any major harmful effect on cells. Sustained release of RosA, and bioactivity of RosA-loaded nanofibers confirmed the potential of the produced matrix as a drug delivery system.

A Phase I study of the pharmacokinetics, safety and tolerability of a novel tocopheryl phosphate mixture/oxymorphone transdermal patch system

AIM

Characterize the pharmacokinetic profile and tolerability of two tocopheryl phosphate mixture/oxymorphone patch formulations in healthy subjects, and the active metabolite (6-OH-oxymorphone).

MATERIALS & METHODS

Fifteen participants received a single application of oxymorphone patches +/- capsaicin for 72 h and were crossed-over for another 72 h.

RESULTS

Plasma oxymorphone was detected approximately 7 h and 6-OH-oxymorphone after approximately 18-19 h postapplication of both formulations, respectively. For oxymorphone, median t_max was 24 h, and C_max/C_min ratio was approximately 2.4. The most frequently reported treatment-related adverse event was application site reaction, mainly with capsaicin formulation.

CONCLUSION

Tocopheryl phosphate mixture/oxymorphone transdermal patches can successfully deliver therapeutic amounts of oxymorphone in a sustained manner over 72 h and are well tolerated. ANZCTR registration number: ACTRN12614000613606.

Efficacy, Safety and Targets in Topical and Transdermal Active and Excipient Delivery

A key requirement for topical and transdermal active delivery is the effective delivery of an active to a desired target site, to achieve both safe and efficacious outcomes. This chapter seeks to explore the importance of the pharmacological, toxicological and therapeutic properties of actives and excipients, as well as the site of action as complementary components in percutaneous absorption. This is crucial for optimized topical and transdermal product design.

Implantable polymeric microneedles with phototriggerable properties as a patient-controlled transdermal analgesia system

Adequate pain control can be achieved using a patient-controlled drug delivery system that can provide analgesia to patients as needed. To achieve this objective, we developed a phototriggered microneedle (MN) system that enables the on-demand delivery of pain medications to the skin under external near-infrared (NIR) light stimulation. In this system, polymeric MNs, containing NIR absorbers and analgesics, are combined with a poly(l-lactide-co-d,l-lactide) supporting array. A "removable design" of the supporting array enables the quick implantation of the MNs into the skin to act as a drug depot, thus shortening the patch application time. Upon irradiation with NIR light, the NIR absorbers in the implanted MNs can absorb light energy and induce a phase transition in the MNs to activate drug release. We demonstrated that lidocaine release can be modulated or repeatedly triggered by varying the duration of irradiation and controlling the on and off status of the laser. Lidocaine delivered by the implanted MNs can be rapidly absorbed into the blood circulation within 10 min and has a bioavailability of at least 95% relative to the subcutaneous injection, showing that the proposed system has the potential to provide a rapid onset of pain relief. Such an implantable device may allow pain sufferers receiving the painkiller without the need for multiple needle injections, and may enable controlling pain more conveniently and comfortably.

Injectable peptide hydrogels for controlled-release of opioids

Peptide-based hydrogels as a drug carrier system for the subcutaneous administration of morphine.

A review of TTS – development, types and preparations

Transdermal Therapeutic Systems (TTS) are elastic multi-layer patches applied to the skin in order to deliver active substances into the bloodstream. One advantage of a transdermal drug delivery route over other types of medication delivery is that the patch provides a noninvasive therapy, longer duration of drug activity, and improves most of bioavailability. TTS consist of a backing layer, a drug, an adhesive, and a release liner. TTS can be divided into five basic types of systems: reservoir, matrix, microreservoir, single-layer drug in adhesive, and multi-layer drug in adhesive. In order to improve the penetration of drugs through the skin, passive and active methods are used. The researchers are constantly developing new methods of improving the delivery of drugs applied by transdermal route.

Exogenous pubertal induction by oral versus transdermal estrogen therapy

Hypogonadal adolescent girls need estrogen therapy for the induction of puberty. For years, oral conjugated estrogens have been used for this purpose, starting at a very low dose, with gradual increments over time, to allow for the maturation of the reproductive organs, in order to mimic physiologic conditions. Several concerns, mainly due to first pass through the liver, are manifest with oral estrogen therapy. With the advent of transdermal estrogens and its improved efficacy profile as well as reduced side effects, it seems reasonable to consider it for pubertal induction. The primary objective of this study was to compare and contrast oral versus transdermal estrogen with regard to metabolism and physiology and to review current available data on transdermal estrogens with respect to exogenous pubertal induction.

Transdermal delivery of methotrexate: past, present and future prospects

Methotrexate has been reported as an immunosuppressant and an antimetabolite widely used in the treatment of rheumatoid arthritis and psoriasis. However, it causes various toxicities and has low bioavailability when taken orally, thus, it is desirable that the drug be delivered transdermally. The water solubility and charged structure of methotrexate, however, limits its use via the transdermal route mainly due to the highly organized microstructure of the stratum corneum. Hence, various technologies, such as chemical enhancers, iontophoresis, electroporation, ultrasound and microneedles, either alone or in combination, are being explored to enhance its permeability by disrupting the barrier property of the skin. The present article discusses the past, present and future of transdermal delivery of methotrexate.