Investigating the sonophoresis effect on the permeation of diclofenac sodium using 3D skin equivalent

Advancements in transdermal drug delivery: A comprehensive review of physical penetration enhancement techniques

Transdermal drug administration has grown in popularity in the pharmaceutical research community due to its potential to improve drug bioavailability, compliance among patients, and therapeutic effectiveness. To overcome the substantial barrier posed by the stratum corneum (SC) and promote drug absorption within the skin, various physical penetration augmentation approaches have been devised. This review article delves into popular physical penetration augmentation techniques, which include sonophoresis, iontophoresis, magnetophoresis, thermophoresis, needle-free injection, and microneedles (MNs) Sonophoresis is a technique that uses low-frequency ultrasonic waves to break the skin's barrier characteristics, therefore improving drug transport and distribution. In contrast, iontophoresis uses an applied electric current to push charged molecules of drugs inside the skin, effectively enhancing medication absorption. Magnetophoresis uses magnetic fields to drive drug carriers into the dermis, a technology that has shown promise in aiding targeted medication delivery. Thermophoresis is the regulated heating of the skin in order to improve drug absorption, particularly with thermally sensitive drug carriers. Needle-free injection technologies, such as jet injectors (JIs) and microprojection arrays, offer another option by producing temporary small pore sizes in the skin, facilitating painless and effective drug delivery. MNs are a painless, minimally invasive method, easy to self-administration, as well as high drug bioavailability. This study focuses on the underlying processes, current breakthroughs, and limitations connected with all of these approaches, with an emphasis on their applicability in diverse therapeutic areas. Finally, a thorough knowledge of these physical enhancement approaches and their incorporation into pharmaceutical research has the potential to revolutionize drug delivery, providing more efficient and secure treatment choices for a wide range of health-related diseases.

Comparative study of permeation effects between vibrating microneedle and low-frequency sonophoresis systems

Microneedle transdermal administration and low-frequency ultrasound represent two important physical penetration-promoting methods for enhancing drug penetration. This article aims to investigate and compare the effects of drug penetration enhancement through transdermal administration using vibrating microneedles versus low-frequency sonophoresis. In Vitro permeation studies were conducted using Valia-Chien double chamber diffusion cells to evaluate the transdermal delivery of tetramethylpyrazine hydrochloride (TMPH). The TMPH concentration in the receiving compartment was determined using high-performance liquid chromatography (HPLC). Several combinations of microneedles and ultrasound settings were investigated, including different needle heights, vibration frequencies, exposure times, and assorted distances of ultrasound horn and skin. The results revealed the vibrating microneedle system as the most efficacious treatment to increase the TMPH permeability into the rat skin. The combination of a larger needle, higher frequency, and a 3-min exposure led to a 41.92-fold increase in cumulative permeability compared to the control group. The ultrasound treatment exhibited a moderate enhancement effect on TMPH skin penetration. Using a horn-to-skin distance of 3 mm and a 3-min exposure resulted in a 4.34-fold increase in TMPH cumulative permeation compared to the control group. It could be concluded that while both the vibrating microneedle and the low-frequency ultrasound systems act as penetration enhancers for promoting the TMPH permeation through the skin, the vibrating microneedle system notably demonstrates a more effective penetration-promoting effect.

Sonophoresis-assisted transdermal delivery of antimigraine-loaded nanolipomers: Radio-tracking, histopathological assessment and in-vivo biodistribution study

Migraine is a disabling neurovascular polygenic disorder affecting life quality with escorted socioeconomic encumbrances. Herein, we investigated the consolidated amalgamation of passive lipomer approach alongside active sonophoresis assisted transdermal delivery of zolmitriptan (ZT) using high frequency ultrasound pre-treatment protocol to mitigate migraine attacks. A modified nanoprecipitation technique was utilized to prepare zolmitriptan loaded lipomers (ZTL) adopting 23 factorial design. Three factors were scrutinized namely lipid type, ZT: lipid ratio and ZT: Gantrez® ratio. The prepared systems were characterized regarding particle size, zeta potential, polydispersity index, entrapment efficiency and in-vitro release studies. The best achieved ZTL system was evaluated for ZT- Gantrez® intermolecular interactions, drug crystallinity, morphology, ex-vivo permeation and histopathological examination. Finally, a comparative in-vivo biodistribution study through radiotracking technique using Technetium-99 m was adopted. L2 was the best-achieved ZTL system with respect to spherical particle size (390.7 nm), zeta-potential (-30.8 mV), PDI (0.2), entrapment efficiency (86.2%), controlled release profile, flux (147.13 μg/cm2/hr) and enhancement ratio (5.67). Histopathological studies proved the safety of L2 system upon application on skin. L2 revealed higher brain Cmax (12.21 %ID/g), prolonged brain MRT (8.67 hr), prolonged brain 0.23 hr), significantly high relative bioavailability (2929.36%) and similar brain Tmax (0.5 hr) compared to I.V. route with higher brain/blood ratio. Thus, sonophoresis assisted transdermal delivery of ZTL offers a propitious alterative to alleviate migraine symptoms.

Phonophoresis through Nonsteroidal Anti-Inflammatory Drugs for Knee Osteoarthritis Treatment: Systematic Review and Meta-Analysis

Knee osteoarthritis (OA) is the most common joint disease. The administration of nonsteroidal anti-inflammatory drugs (NSAIDs) by phonophoresis is a therapeutic alternative to relieve pain in inflammatory pathologies. The main aim was to analyze the efficacy of the application of NSAIDs by phonophoresis in knee OA. A systematic review and meta-analysis of controlled clinical trials were performed between January and March 2021 in the following databases: Web of Science, Scopus, PubMed, Cinahl, SciELO, and PEDro. The PEDro scale was used to evaluate the level of evidence of the selected studies. The RevMan 5.4 statistical software was used to obtain the meta-analysis. Eight studies were included, of which five were included in the meta-analysis, involving 195 participants. The NSAIDs used through phonophoresis were ibuprofen, piroxicam, diclofenac sodium, diclofenac diethylammonium, ketoprofen, and methyl salicylate. The overall result for pain showed not-conclusive results, but a trend toward significance was found in favor of the phonophoresis group compared to the control group (standardized mean difference (SMD) = -0.92; 95% confidence interval: -1.87-0.02). Favorable results were obtained for physical function (SMD = -1.34; 95% CI: -2.00-0.68). Based on the selected studies, the application of NSAIDs by phonophoresis is effective in relieving the symptoms of knee OA. Future long-term studies are recommended.

Low-Frequency Sonophoresis as an Active Approach to Potentiate the Transdermal Delivery of Agomelatine-Loaded Novasomes: Design, Optimization, and Pharmacokinetic Profiling in Rabbits

The first melatonergic antidepressant drug, agomelatine (AGM), is commonly used for controlling major depressive disorders. AGM suffers low (< 5%) oral bioavailability owing to the hepatic metabolism. The current work investigated the potential of low-frequency sonophoresis on enhancing transdermal delivery of AGM-loaded novasomes and, hence, bioavailability of AGM. Drug-loaded novasomes were developed using free fatty acid (stearic acid or oleic acid), surfactant (span 60 or span 80), and cholesterol via thin-film hydration technique. The systems (N1-N16) were assessed for zeta potential (ZP), particle size (PS), encapsulation efficiency (EE%), and drug percent released after 0.5 h (Q_0.5 h) and 8 h (Q_8h), drug-crystallinity, morphology, and ex vivo drug permeation. Skin pre-treatment with low-frequency ultrasound (LFU) waves, via N13-novasomal gel systems, was optimized to enhance ex vivo drug permeation. Influences of LFU mode (continuous or pulsed), duty cycle (50% or 100%), and application period (10 or 15 min) were optimized. The pharmacokinetics of the optimized system (N13-LFU-C4) was assessed in rabbits. N13 was the best achieved novasomal system with respect to PS (471.6 nm), ZP (- 63.6 mv), EE% (60.5%), Q_0.5 h (27.8%), Q_8h (83.9%), flux (15.5 μg/cm²/h), and enhancement ratio (6.9). N13-LFU-C4 was the optimized novasomal gel system (desirability; 0.997) which involves skin pre-treatment with LFU in a continuous mode, at 100% duty cycle, for 15 min. Compared to AGM dispersion, the significantly (P < 0.05) higher flux (26.7 μg/cm²/h), enhancement ratio (11.9), C_max (118.23 ng/mL), and relative bioavailability (≈ 8.6 folds) could elucidate the potential of N13-LFU-C4 system in improving transdermal drug permeability and bioavailability.

Low-Intensity Continuous Ultrasound Therapies—A Systematic Review of Current State-of-the-Art and Future Perspectives

Therapeutic ultrasound has been studied for over seven decades for different medical applications. The versatility of ultrasound applications are highly dependent on the frequency, intensity, duration, duty cycle, power, wavelength, and form. In this review article, we will focus on low-intensity continuous ultrasound (LICUS). LICUS has been well-studied for numerous clinical disorders, including tissue regeneration, pain management, neuromodulation, thrombosis, and cancer treatment. PubMed and Google Scholar databases were used to conduct a comprehensive review of all research studying the application of LICUS in pre-clinical and clinical studies. The review includes articles that specify intensity and duty cycle (continuous). Any studies that did not identify these parameters or used high-intensity and pulsed ultrasound were not included in the review. The literature review shows the vast implication of LICUS in many medical fields at the pre-clinical and clinical levels. Its applications depend on variables such as frequency, intensity, duration, and type of medical disorder. Overall, these studies show that LICUS has significant promise, but conflicting data remain regarding the parameters used, and further studies are required to fully realize the potential benefits of LICUS.

Low-Frequency versus High-Frequency Ultrasound-Mediated Transdermal Delivery of Agomelatine-Loaded Invasomes: Development, Optimization and in-vivo Pharmacokinetic Assessment

Aim

Agomelatine (AGM) is the first melatonergic antidepressant. It suffers from low oral bioavailability (<5%) due to extensive hepatic metabolism. The current work aimed to develop an alternative AGM-loaded invasomes to enhance transdermal drug bioavailability.

Methodology

AGM-loaded invasomes were developed using two drug: lipid ratios (1:10 or 1:7.5), four terpene types (limonene, cineole, fenchone or citral) and two terpene concentrations (0.75% or 1.5%, w/v). They were characterized for drug entrapment efficiency (EE%), particle size (PS), zeta potential (ZP) and drug released percentages after 0.5h (Q_0.5h) and 8h (Q_8h). The optimum invasomes (I1, I2 and I4) were evaluated for morphology, drug-crystallinity, and ex-vivo drug flux. The variables influencing sonophoresis of the best achieved invasomal gel system (I2) were optimized including, ultrasound frequency (low, LFU or high, HFU), mode (pulsed or continuous), application period (10 min or 15 min) and duty cycle (50% or 100%). AGM pharmacokinetics were evaluated in rabbits following transdermal application of I2-LFU-C4 system, relative to AGM oral dispersion.

Results

The superiority of I2 invasomes [comprising AGM and phosphatidylcholine (1:10) and limonene (1.5% w/v)] was statistically revealed with respect to EE% (78.6%), PS (313 nm), ZP (−64 mV), Q_0.5h (30.1%), Q_8h (92%), flux (10.79 µg/cm2/h) and enhancement ratio (4.83). The optimum sonophoresis conditions involved application of LFU in the continuous mode for 15 min at a 100% duty cycle (I2-LFU-C4 system). The latter system showed significantly higher C_max, and relative bioavailability (≈ 7.25 folds) and a similar T_max (0.5 h).

Conclusion

I2-LFU-C4 is a promising transdermal system for AGM.

Sustained acoustic medicine; sonophoresis for nonsteroidal anti-inflammatory drug delivery in arthritis

Background: Arthritis pain is primarily managed by nonsteroidal anti-inflammatory drugs (NSAIDs), such as diclofenac. Topical diclofenac gel is limited in efficacy due to its limited penetration through the skin. This study investigates the use of a multihour, wearable, localized, sonophoresis transdermal drug delivery device for the penetration enhancement of diclofenac through the skin. Materials & methods: A commercially available, sustained acoustic medicine (sam®) ultrasound device providing 4 h, 1.3 W, 132 mW/cm2, 3 MHz ultrasound treatment was evaluated for increasing the drug delivery of diclofenac gel through a human skin model and was compared with standard of care topical control diclofenac gel. Results: Sonophoresis of the diclofenac gel for 4 h increases diclofenac delivery by 3.8× (p < 0.01), and penetration by 32% (p < 0.01). Conclusion: Sustained acoustic medicine can be used as a transdermal drug-delivery device for nonsteroidal anti-inflammatory drugs.

Ultrasound-mediated topical delivery of econazole nitrate with potential for treating Raynaud's phenomenon

The study aims to assess the ultrasound-assisted econazole nitrate (EN) permeation from topically applied formulations with potential for treating Raynaud's phenomenon. Optimization of ultrasound parameters such as the distance of the horn, application time and amplitude were performed. In vitro percutaneous absorption studies were performed using econazole formulations (F2_HPMC dispersion, F4_Lipoderm® Activemax™ Cream) across the ultrasound-treated porcine skin and were compared with the control group (skin samples without ultrasound). Histology and ATR-FTIR studies were performed on treated skin samples. A constant frequency (20 kHz) ultrasound application with 40% amplitude, 0.5 cm distance between ultrasound horn and the skin surface for 2 min was optimized. The permeation of EN was found to be higher from ultrasound-treated skin samples than the control group. Drug permeation from F2_HPMC dispersion was found to be higher as compared to the other formulations and the marketed EN cream. Histological evaluation confirmed that F2_HPMC dispersion showed no signs of toxicity. ATR-FTIR studies revealed a slight increase in the CH₂ stretching vibrations (~2920 cm^-1 and 2850 cm^-1) in ultrasound-treated skin samples as compared with the control. In conclusion, the ultrasound-assisted transdermal delivery of F2_HPMC dispersion could be further studied as a new therapy for Raynaud's phenomenon.

Effect of Ultrasound Intensity and Mode on Piroxicam Transport Across Three-Dimensional Skin Equivalent Epiderm™

BACKGROUND

Transdermal drug delivery has many advantages compared to other routes. However, the barrier function of the stratum corneum limits the use of the skin as an administrative route for medications. Different methods were investigated to alter the barrier function of the stratum corneum and it was found that applying different ultrasound waves could enhance the skin's permeability.

OBJECTIVE

The aim of this work is to study the effect of ultrasonic waves on the alteration of skin natural barrier function, to improve the permeability of the skin to Piroxicam using three-dimension skin (EpiDermTM) as a skin model for the investigation.

METHOD

The effect of ultrasound at 1 MHz and 20 kHz on the permeation of Piroxicam across the three-dimensional skin equivalent using a Franz diffusion cell, was evaluated and the concentration of Piroxicam in the receiving compartment was determined using liquid chromatography method.

RESULTS

The permeation of Piroxicam enhanced by 199% when therapeutic ultrasound at 1 MHz frequency was used. Significant permeation enhancement was also found upon utilizing low frequency sonophoresis at 20 kHz (427%) with no apparent damage to the membrane.

CONCLUSION

Sonophoresis has a positive effect on enhancing skin permeability. The enhancement level was largely dependent on the sonication factors; frequency, intensity and length of treatment. Multiple mechanisms of action might be involved in permeation improvement of the piroxicam molecule. Those mechanisms are largely dependent on the ultrasonic conditions.

Advances in Ultrasound Mediated Transdermal Drug Delivery

Low frequency ultrasound-assisted drug delivery has been widely investigated as a non-invasive method to enhance the transdermal penetration of drugs. Using this technique, a brief application of ultrasound is used to permeabilize skin for a prolonged time. In this review, an overview on ultrasound is detailed to help explain the parameters that could be modulated to obtain the desired ultrasound parameters for enhanced transdermal drug delivery. The mechanisms of enhancement and the latest developments in the area of ultrasound-assisted transdermal drug delivery are discussed. Special emphasis is placed on the effects of ultrasound when used in combination with microneedles, electroporation and iontophoresis, and penetration enhancers. Further, this review summarizes the effect of ultrasound on skin integrity and the regulatory requirements for commercialization of the ultrasound based transdermal delivery instruments.

Recent advances in ultrasound-based transdermal drug delivery

The transdermal transport of pharmaceuticals possesses various advantageous properties over conventional drug administration techniques such as oral delivery and hypodermic injections. However, the stratum corneum persists as the main barrier, which impedes percutaneous transport. The ultrasound-based transdermal delivery of therapeutics is one of the techniques that are being investigated to overcome this obstacle. This review outlines the background information pertaining to sonophoresis and then discusses the individual sections of sonophoretic research. These areas include the sonophoretic application of various drugs, dual-frequency sonophoresis, synergistic combinations of transdermal drug delivery techniques, and the use of nanosized carriers in ultrasound-based transdermal delivery. The various challenges associated with sonophoretic drug delivery and trends of future research are also highlighted.

Development and validation of a new HPLC analytical method for the determination of diclofenac in tablets

A new selective and sensitive high-performance liquid chromatography (HPLC) method was developed for the quantification of diclofenac sodium (DS) in pharmaceutical dosage form using lidocaine as internal standard (IS). Chromatographic separation was achieved on a symmetry C18 column (4.6 mm × 150 mm, 3 μm spherical particles) using 0.05 M orthophosporic (pH 2.0) 35% and acetonitrile as 65%, as the mobile phase at a flow rate of 2.0 mL/min and monitored at 210 nm. The run time was 2 min. The method was validated to fulfill International Conference on Harmonisation (ICH) requirements and this validation included specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision and robustness. The calibration curve was linear over the concentration range from 10 to 200 µg/ml, and lower limit of detection of 12.5 ng/ml. The accuracy and precision of the method were within the acceptable limit of ±20% at the lower limit of quantitation and ±15% at other concentrations. Diclofenac was unstable at room temperature it showed more than 25% loss after 24 h. While, DS is very stable at refrigerator 4 °C auto-sampler, freeze/thaw cycles and 30 days storage in a freezer at -35 ± 2 °C. All results were acceptable and this confirmed that the method is suitable for its intended use in routine quality control and assay of drugs.

Spiral computed tomography evaluation of rabbit VX2 hepatic tumors treated with 20 kHz ultrasound and microbubbles

The aim of the present study was to explore the therapeutic effect of 20 kHz ultrasound (US) and microbubbles (MBs) on rabbit VX2 liver tumors by spiral computed tomography (CT) scanning. A total of 16 New Zealand rabbits with hepatic VX2 tumors were divided into four groups: Control, MB, low-frequency US and US + MB. The treatment effect was evaluated by spiral CT scanning prior to, during and following treatment (at 0 weeks and the end of 1 and 2 weeks). The tumor growth rate was recorded. The specimens of VX2 tumors were collected for histological examination and transmission electron microscopy (TEM). No significant differences were observed between tumor areas measured by CT and pathology after 2-week treatment (P>0.05). The mean tumor growth rates in the control, MB, US and US + MB groups after 2 weeks of treatment were 385±21, 353±12, 302±14 and 154±9%, respectively (P<0.05, US + MB vs. the other three groups). Hematoxylin and eosin staining in the US + MB group revealed coagulation necrosis, interstitial hemorrhage and intravascular thrombosis. In the control, MB and US groups, tumor cells exhibited clear nuclear hyperchromatism. TEM of US + MB revealed vascular endothelial cell wall rupture, widened endothelial cell gaps, interstitial erythrocyte leakage and microvascular thrombosis, while intact vascular endothelial cells and normal erythrocytes in the tumor vessels were observed in the control, MB and US groups. A combination of 20 kHz US and MBs may effectively inhibit rabbit VX2 tumors. Spiral CT scanning is an ideal method to evaluate the US treatment on rabbit tumors.

Thermal analyses of in vitro low frequency sonophoresis

As a type of transdermal drug delivery method, low frequency sonophoresis (LFS) has been investigated during the last twenty years and is currently being attempted in a clinical setting. However, the safety of low frequency ultrasound on humans has not been completely guaranteed with high-intensity ultrasound. Thermal damage, one of the challenges in the LFS process, e.g., burns, epidermal detachment and necrosis of tissues, hinders its widespread applications. To predict and impede the overheating problems in LFS, an acoustic-flow-thermal finite element method (FEM) based on COMSOL Multiphysics software is proposed in this paper to achieve thermal analyses. The temperature distribution and its rising curves in in vitro LFS are obtained by the FEM method and experimental measurements. Both simulated and experimental maximum temperatures are larger than the safety value (e.g., 42°C on human tissues) when the driving voltage is higher than 40V (5.5W input electric power), which proves that the overheating problem really exists in high-intensity ultrasound. Furthermore, the results show that the calculated temperature rising curves in in vitro LFS correspond to the experimental results, proving the effectiveness of this FEM method. In addition, several potential thermal influence factors have been studied, including a duty ratio and amplitude of the driving voltage, and liquid height in the donor, which may be helpful in restraining the temperature increase to limit thermal damage. According to the calculated and experimental results, the former two factors are sensitive to the rise in temperature, but a small scale of liquid volume increase can enhance the permeation of Calcein without obvious temperature change. Hence, the above factors can be synthetically utilized to restrain the rise in temperature with little sacrifice of permeation ability. So this acoustic-flow-thermal FEM method could be applied to an optimized LFS system design and simulating the thermal analyses of LFS in healthy human body in terms of safe thermal limits.