Nicotine transdermal patches using polymeric natural rubber as the matrix controlling system: Effect of polymer and plasticizer blends

The impact of non-deproteinization on physicochemical and biological properties of natural rubber latex for biomedical applications

Latex is a colloidal suspension derived from the Hevea brasiliensis tree, derived from natural rubber, poly(isoprene), and assorted constituents including proteins and phospholipids. These constituents are inherent to both natural rubber and latex serum. This investigation was undertaken to examine the impact of the deproteinization process on chemical and biological dynamics of natural rubber latex. Natural Rubber (NR) extracted from the pure latex (LNCP) was obtained through centrifugation, followed by six rounds of solvent purification (LP6). The structure was characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), swelling test, surface zeta potential (ζ), scanning electron microscopy (SEM) and in vitro assay. The results revealed that the LP6 group presented decreased swelling kinetics, reduced cell adhesion and proliferation, and a smoother surface with decreased negative surface charge. Conversely, the LNCP group shown accelerated swelling, heightened adhesion and cellular growth, and a more negatively charged and rougher surface. As such, the attributes of latex serum and proteins have potential usage across numerous biomedical applications.

Effect of glycerol and dibutyl phthalate on modified natural rubber latex based drug delivery systems

The work highlights the impact of the incorporation of two pharmaceutical plasticizers viz.; glycerol (GLY; hydrophilic) and dibutyl phthalate (DBP; hydrophobic) on the controlled drug release features of a deproteinised natural rubber latex (DNRL) -based matrix. The effects of the plasticizers on the mechanical properties, glass transition temperature (T_g), water absorption behaviour and porosity of DNRL have been initially investigated. The plasticized membranes have been found to show a hemolysis percentage (HP) of <5 %; confirming its compatibility with human blood. The potential of the modified DNRL membranes to function as drug carriers have been examined with metformin hydrochloride (MET) as a model drug.

Development and Characterisation of a Topical Methyl Salicylate Patch: Effect of Solvents on Adhesion and Skin Permeation

The advent of skin patch formulation design and technology has enabled the commercialisation of methyl salicylate (MS) as a topical patch. However, the most fundamental aspect of skin permeation is unknown at present. The study aims to investigate the effect of solvent choice on the skin permeation of MS in a neat solvent system and patch formulation with an emphasis on patch adhesion. MS in six selected solvents (propylene glycol (PG), Transcutol^®, isopropyl myristate, Labrasol^®, Plurol^® oleique CC 497 and Maisine^® CC) was characterised and in vitro permeation studies were also performed. An ATR-FTIR analysis on solvent-treated skin was conudcted. Patch formulation was prepared and characterised for adhesion, in vitro drug release and skin permeation studies. The highest MS permeation was found in neat PG over 24 h (~90 μg/cm²) due to its strong skin protein conformation effect. Transcutol^® and isopropyl myristate showed better skin deposition and formulation retention, respectively. Nevertheless, PG enhanced the patch adhesion despite having a lower cumulative amount of MS permeated (~80 μg/cm²) as compared with Transcutol^® and Maisine^® (~110-150 μg/cm²). These two solvents, however, demonstrated better skin deposition and formulation retention but a lower patch adhesion. The unpredictable influence of the solvent on patch adhesion highlights the importance of the trade-off between patch adhesion and skin permeation during formulation design.

Sustained drug delivery strategies for treatment of common substance use disorders: Promises and challenges

Substance use disorders (SUDs) are a leading cause of death and other ill health effects in the United States and other countries in the world. Several approaches ranging from detoxification, behavioral therapy, and the use of antagonists or drugs with counter effects are currently being applied for its management. Amongst these, drug therapy is the mainstay for some drug abuse incidences, as is in place specifically for opioid abuse or alcohol dependence. The severity of the havocs observed with the SUDs has triggered constant interest in the discovery and development of novel medications as well as suitable or most appropriate methods for the delivery of these agents. The chronic need of such drugs in users warrants the need for their prolonged or sustained systemic availability. Further, the need to improve patient tolerance to medication, limit invasive drug use and overall treatment outcome are pertinent considerations for embracing sustained release designs for medications used in managing SUDs. This review aims to provide an overview on up-to-date advances made with regards to sustained delivery systems for the drugs for treatment of different types of SUDs such as opioid, alcohol, tobacco, cocaine, and cannabis use disorders. The clinical relevance, promises and the limitations of deployed sustained release approaches along with future opportunities are discussed.

Applying design of experiments (DoE) on the properties of buccal film for nicotine delivery

Design of experiments is used to optimize ratios between deproteinized natural rubber latex, Eudragit® NM 30 D, and pectin for nicotine buccal film with dependent variables as moisture content, moisture uptake, and swelling index in simulated saliva 3 and 5 h. Mathematical models were linear for moisture content and moisture uptake, while swelling index in simulated saliva 3 and 5 h was a quadratic model. Optimized polymer ratio was 0.319:0.362:0.319, respectively. Experimental values were 13.17 ± 0.92%, 3.96 ± 0.84%, 112.58 ± 22.63%, and 124.69 ± 8.01% for dependent variables, respectively. The buccal film showed high swelling at pH 7 and swelling–deswelling behaviors in a water/ethanol environment. The surface pH, weight, and thickness were 8.11, 63.28 ± 6.18 mg, and 219.87 ± 44.28 µm, respectively. Nicotine content was found as 10.22 ± 0.46 mg/4 cm2. Maximum cumulative nicotine release was 9.82 ± 0.94 mg/4 cm2. Kinetic model fitted to the Korsmeyer-Peppas model and release exponent was 0.36, representing that release mechanism was controlled by Fickian diffusion release.

Influence of chitosan thioglycolic acid conjugate in improving bioavailability of an antiparkinson drug; Rasagiline Mesylate from transdermal patch

OBJECTIVE

Parkinson disease (PD) is a chronic disorder of central nervous system mainly affecting the motor systems. The drug of choice to treat PD is Rasagiline Mesylate (RM) and it belongs to BCS class III drug. The objective of the present study was the preparation of transdermal drug delivery system for RM. Several permeation enhancers were screened to be included in the formulation. To achieve desired flux a new strategy was developed by including in-house prepared CTC to enhance the permeation of RM.

METHODS

The CTC was prepared by reaction between chitosan and thioglycolicacid, characterized by determining physical properties and applying analytical tools. Seven permeation enhancers with different mechanisms were screened. The transdermal patches were prepared with chitosan along with permeation enhancer IPM, various proportions of CTC and evaluated for physical and permeation studies. The optimized transdermal patch was obtained by two factors and three responses to obtain the design space and further evaluated for pharmacokinetic studies.

RESULTS

The results of the present study confirmed the formation of CTC, IPM was best permeation enhancer among all. The presence of CTC in the formulations significantly improved the permeation of RM to achieve desired steady-state flux. The relative bioavailability of optimized transdermal patch was determined and it was observed that improved bioavailability as compared to marketed conventional tablets.

CONCLUSION

The study was concluded that CTC has significant influence on permeation enhancing ability of IPM.

Study on controlling nicotine release from snus by the SIPN membranes

Snus is one of the types of smokeless tobaccos, which is popular in many countries and regions. The nicotine level in the plasma samples obtained from snus users is similar to the nicotine level obtained from cigarette smokers; hence, the snus users find it difficult to quit. The aim of this study is to develop new semi-interpenetrating polymer (SIPN) membranes that control the stable release of nicotine from snus, achieving the purpose of quitting smoking. Here, the SIPN comprising a polyacrylate network and PEG chains was synthesized through in situ radical polymerization. The SIPN was characterized by Fourier transform infrared spectroscopy, contact angle, differential scanning calorimetry, scanning electron microscopy, cytotoxicity, and in vitro release experiments. Furthermore, this SIPN was used to evaluate the release properties of nicotine in different snus samples varying in moisture, pH, and the tobacco’s particle size. The results indicated that the new SIPN could control release of nicotine at a specific rate, and the release rate could be adjusted according to the customer requirements. Thus, the new SIPN was contributed to build a new nicotine replacement therapy that served the snus users.

Advances in Molecularly Imprinted Polymers as Drug Delivery Systems

Despite the tremendous efforts made in the past decades, severe side/toxic effects and poor bioavailability still represent the main challenges that hinder the clinical translation of drug molecules. This has turned the attention of investigators towards drug delivery vehicles that provide a localized and controlled drug delivery. Molecularly imprinted polymers (MIPs) as novel and versatile drug delivery vehicles have been widely studied in recent years due to the advantages of selective recognition, enhanced drug loading, sustained release, and robustness in harsh conditions. This review highlights the design and development of strategies undertaken for MIPs used as drug delivery vehicles involving different drug delivery mechanisms, such as rate-programmed, stimuli-responsive and active targeting, published during the course of the past five years.

Applications of polymer blends in drug delivery

Background

Polymers are essential components of many drug delivery systems and biomedical products. Despite the utility of many currently available polymers, there exists a demand for materials with improved characteristics and functionality. Due to the extensive safety testing required for new excipient approval, the introduction and use of new polymers is considerably limited. The blending of currently approved polymers provides a valuable solution by which the limitations of individual polymers can be addressed.

Main body

Polymer blends combine two or more polymers resulting in improved, augmented, or customized properties and functionality which can result in significant advantages in drug delivery applications. This review discusses the rationale for the use of polymer blends and blend polymer-polymer interactions. It provides examples of their use in commercially marketed products and drug delivery systems. Examples of polymer blends in amorphous solid dispersions and biodegradable systems are also discussed. A classification scheme for polymer blends based on the level of material processing and interaction is presented.

Conclusion

The use of polymer blends represents a valuable and under-utilized resource in addressing a diverse range of drug delivery challenges. It is anticipated that new drug molecule development challenges such as bioavailability enhancement and the demand for enabling excipients will lead to increased applications of polymer blends in pharmaceutical products.

Graphical abstract

Xanthan Gum-Incorporated Natural Rubber Film Casted with Solvent Evaporation

Xanthan gum (X)-incorporated natural rubber (NR) cast films were fabricated from blocked NR by solvent casting method using dichloromethane as the solvent. The rather smooth films were obtained. X markedly promoted both of water sorption and erosion in phosphate buffer pH 7.4 of these composite films. With increasing X amount also significantly enhanced the film tensile strength, Young’s modulus and area under the curve while did not affect contact angle of water/formamide and surface free energy. 30%X-loaded NR films exhibited the highest durability with apparently high water sorption and erosion for further using such as wound dressing.

Comparison of Pectin Layers for Nicotine Transdermal Patch Preparation

Purpose: The objective of the present investigation was to prepare and evaluate transdermal patches for nicotine.

Methods: Pectin isolated from the hulls of Monthong durian or leaves of Krueo Ma Noy was used as a matrix membrane for the controlled release of nicotine and compared with commercial pectin. The mechanical properties, moisture uptake, and Fourier transform infrared spectra were characterized. The in vitro stability of these patches was evaluated and compared to commercial nicotine patches.

Results: The mechanical properties of the patches made from isolated pectin were greater than those prepared from commercial pectin; brittle commercial patches were obtained after nicotine loading. The moisture uptake of the patches made with isolated pectin was in the range of 30.20-44.29%. There was no incompatibility between the ingredients of the nicotine transdermal patches or any degradation of the drug. The matrix layer made from isolated pectin controlled the nicotine release more effectively than did commercial nicotine patches. In addition, these patches were stable at in a refrigerator (approximately 4±2 °C) and at ambient temperature (approximately 30±2 °C) for 3 months, retaining 90% of the loaded nicotine.

Conclusion: Our study suggests that using isolated pectin as the matrix layer should control the release of nicotine from transdermal patches.

Biomaterials for drug delivery patches

The limited efficiency of conventional drugs has been instigated the development of new and more effective drug delivery systems (DDS). Transdermal DDS, are associated with numerous advantages such its painless application and less frequent replacement and greater flexibility of dosing, features that triggered the research and development of such devices. Such systems have been produced using either biopolymer; or synthetic polymers. Although the first ones are safer, biocompatible and present a controlled degradation by human enzymes or water, the second ones are the most currently available in the market due to their greater mechanical resistance and flexibility, and non-degradation over time. This review highlights the most recent advances (mainly in the last five years) of patches aimed for transdermal drug delivery, focusing on the different materials (natural, synthetic and blends) and latest designs for the development of such devices, emphasizing also their combination with drug carriers that enable enhanced drug solubility and a more controlled release of the drug over the time. The benefits and limitations of different patches formulations are considered with reference to their appliance to transdermal drug delivery. Furthermore, a record of the currently available patches on the market is given, featuring their most relevant characteristics. Finally, a list of most recent/ongoing clinical trials regarding the use of patches for skin disorders is detailed and critical insights on the current state of patches for transdermal drug delivery are also provided.

Mechanical Properties of Herbal Patches from Chitosan-Based Polymer Blends for Medical Applications

Recently, Thai herbs are widely used as medicine to treat some illnesses. Zingiber cassumunar Roxb., known by the Thai name “Plai”, is a popular anti-inflammatory, antispasmodic herbal body and muscle treatment. This research aimed to prepare herbal patches that incorporated the 3 g of crude Z. cassumunar oil. The herbal patches made from different polymer blends were 2 g of 3.5%w/v chitosan and 5 g of 20%w/v hydroxypropyl methylcellulose (HPMC), or 2 g of 3.5%w/v chitosan and 5 g of 20%w/v polyvinyl alcohol (PVA) using 2 g of glycerin as a plasticizer. They were prepared by mixing all ingredients in a beaker and produced by solvent casting method in hot air oven at 70±2oC. The completed herbal patches were evaluated for their mechanical properties including Young’s modulus, ultimate tensile strength, elongation at break, T-peel strength, and tack adhesion. The thickness of blank and herbal patches was 0.263-0.282 mm and 0.269-0.275 mm, respectively. Young’s modulus, ultimate tensile strength, elongation at break, T-peel strength, and tack adhesion were 104.73-142.71 MPa, 87.92-93.28 MPa, 154.39-174.98 %, 3.43-4.88 MPa, and 5.29-7.02 MPa, respectively, for blank patches, and 116.83-147.28 MPa, 89.49-100.47 MPa, 133.78-159.27 %, 2.01-3.98 MPa, and 4.03-5.19 MPa, respectively, for herbal patches. We prepared herbal blended patches made from chitosan/PVA or chitosan/HPMC polymer matrix blends incorporating the crude Z. cassumunar oil. They had good mechanical properties that might be developed for herbal medicinal application.

Novel membranes from physico-chemically modified deproteinized natural rubber latex: development, characterisation and drug permeation

Novel blend membranes from physico-chemically modified deproteinized natural rubber latex for drug release applications.

Deproteinised natural rubber latex grafted poly(dimethylaminoethyl methacrylate) - poly(vinyl alcohol) blend membranes: Synthesis, properties and application

Natural rubber latex was initially deproteinised (DNRL) and then subjected to physicochemical modifications to make high functional membranes for drug delivery applications. Initially, DNRL was prepared by incubating with urea, sodiumdodecylsulphate and acetone followed by centrifugation. The deproteinisation was confirmed by CHN analysis. The DNRL was then chemically modified by grafting (dimethylaminoethyl methacrylate) onto NR particles by using a redox initiator system viz; cumene hydroperoxide/tetraethylenepentamine, followed by dialysis for purification. The grafting was confirmed by dynamic light scattering, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The grafted system was blended with a hydrophilic adhesive polymer PVA and casted into membranes. The membranes after blending showed enhanced mechanical properties with a threshold concentration of PVA. The moisture uptake, swelling and water contact angle experiments indicated an increased hydrophilicity with an increased PVA content in the blend membranes. The grafted DNRL possessed significant antibacterial property which has been found to be retained in the blended form. A notable decrease in cytotoxicity was observed for the modified DNRL membranes than the bare DNRL membranes. The in-vitro drug release studies using rhodamine B as a model drug, confirmed the utility of the prepared membranes to function as a drug delivery matrix.

Formulation of Polyherbal Patches Based on Polyvinyl Alcohol and Hydroxypropylmethyl Cellulose: Characterization and In Vitro Evaluation

The purpose of this research was to prepare and characterize polyherbal patches made from polyvinyl alcohol (PVA) and hydroxypropylmethyl cellulose (HPMC) with glycerine as a plasticizer. Polyherbal extracts were Luk-Pra-Kob recipes extracted with 95% ethanol. They were prepared by mixing the polymer solutions and glycerine in a beaker; subsequently, the polyherbal extracts were homogeneously mixed. Then, they were transferred into a Petri dish and dried in a hot-air oven at 70 ± 2°C for 5 h. The dry polyherbal patches were evaluated for physicochemical properties by Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, and a scanning electron microscope. They were studied for in vitro release and skin permeation of the marker active compound (E)-4-(3',4'-dimethoxyphenyl)but-3-en-l-ol (compound D) using a modified Franz-type diffusion cell. The polyherbal patches made from PVA as a matrix layer were homogeneous, smooth, and compact relative to HPMC-containing polyherbal patches. The selected polyherbal patches made from PVA produced a release profile with an initial burst effect in which compound D release was 74.21 ± 6.13% within 8 h, but compound D could permeate the pig skin only 37.28 ± 5.52% and was highly accumulated in newborn pig skin at 35.90 ± 6.72%. The in vitro release and skin permeation kinetics of compound D were fitted to the Higuchi model. The polyherbal patches made from PVA could be suitably used for herbal medicine application.

Diclofenac Potassium Transdermal Patches Using Natural Rubber Latex Biomembranes as Carrier

The aim of this study was to design a compound transdermal patch containing diclofenac potassium (Dic-K) using natural rubber latex (NRL) biomembrane. The NRL from Hevea brasiliensis is easily manipulated and low cost and presents high mechanical resistance. It is a biocompatible material which can stimulate natural angiogenesis and is capable of adhering cells on its surface. Recent researches have used the NRL for Transdermal Drug Delivery Systems (TDDSs). Dic-K is used for the treatment of rheumatoid arthritis and osteoarthritis and pain relief for postoperative and posttraumatic cases, as well as inflammation and edema. Results showed that the biomembrane can release Dic-K for up to 216 hours. The kinetics of the Dic-K release could be fitted with double exponential function. X-ray diffraction and Fourier Transform Infrared (FTIR) spectroscopy show some interaction by hydrogen bound. The results indicated the potential of the compound patch.

Quality by design coupled with near infrared in formulation of transdermal glimepiride liposomal films

This study is aimed at developing glimepiride (GMD) liposomal films using quality by design (QbD) and process analytical technology (PAT) principles. Risk analysis and Plackett-Burman design were utilized to evaluate formulation variables in two paths. Internal path included liposomal parameters (phosphatidylserine, cholesterol and drug concentrations, and pH of hydration medium). External path constituted films parameters, namely, polymer, plasticizer, and permeation enhancer percentages. As a PAT tool, near infrared (NIR)-based chemometric analysis was used in quantifying GMD contents. Liposomal formulations showed maximum GMD entrapment capacity of 41.9% with vesicular size of 0.51 μm at phospholipid to cholesterol to drug weight ratio of 2:1:0.8. Its transdermal films showed elongation ratio of 75%, folding endurance of 700-fold, 16.6% and 26.8% drug release after 1 and 12 h, respectively. Moreover, 3D response spaces for GMD entrapment and release characteristics were established. Regarding NIR analysis, partial-least-square regression model was accurate in quantifying drug content as indicated by the low root-mean-squared error of calibrations and prediction of 0.031 and 0.032, and bias values of 0.0015 and 0.0021, respectively. In conclusion, this study highlights the level of understanding that can be accomplished through a well-designed research based on QbD and PAT paradigms.

Formulation, physicochemical characterization, and in vitro study of chitosan/HPMC blends-based herbal blended patches

The current work prepared chitosan/hydroxypropyl methylcellulose (HPMC) blends and studied the possibility of chitosan/HPMC blended patches for Zingiber cassumunar Roxb. The blended patches without/with crude Z. cassumunar oil were prepared by homogeneously mixing the 3.5% w/v of chitosan solution and 20% w/v of HPMC solution, and glycerine was used as plasticizer. Then, they were poured into Petri dish and produced the blended patches in hot air oven at 70 ± 2°C. The blended patches were tested and evaluated by the physicochemical properties: moisture uptake, swelling ratio, erosion, porosity, Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction, and photographed the surface and cross-section morphology under SEM technique. Herbal blended patches were studied by the in vitro release and skin permeation of active compound D. The blended patches could absorb the moisture and became hydrated patches that occurred during the swelling of blended patches. They were eroded and increased by the number of porous channels to pass through out for active compound D. In addition, the blended patches indicated the compatibility of the blended ingredients and homogeneous smooth and compact. The blended patches made from chitosan/HPMC blends provide a controlled release and skin permeation behavior of compound D. Thus, the blended patches could be suitably used for herbal medicine application.

Transdermal nitroglycerin delivery using acrylic matrices: design, formulation, and in vitro characterization

Nitroglycerin (TNG) transdermal drug delivery systems (TDDSs) with different acrylic pressure-sensitive adhesives (PSAs) and chemical permeation enhancers (CPEs) were prepared. The effects of PSAs and CPEs types and concentrations on skin permeation and in vitro drug release from devices were evaluated using the dissolution method as well as the modified-jacketed Franz diffusion cells fitted with excised rat abdominal skin. It was demonstrated that the permeation rate or steady state flux (J_ss) of the drug through the excised rat skin was dependent on the viscosity and type of acrylic PSA as well as the type of CPE. Among different acrylic PSAs, Duro-Tak 2516 and Duro-Tak 2054 showed the highest and Duro-Tak 2051 showed the lowest J_ss. Among the various CPEs, propylene glycol and cetyl alcohol showed the highest and the lowest enhancement of the skin permeation of TNG, respectively. The adhesion properties of devices such as 180° peel strength and probe tack values were obtained. It was shown that increasing the concentration of CPE led to reduction in the adhesion property of PSA. Moreover, after optimization of the formulation, it was found that the use of 10% PG as a CPE and 25% nitroglycerin loading in Duro-Tak 2054 is an effective monolithic DIAP for the development of a transdermal therapeutic system for nitroglycerin.