Oleodendrimers: A novel class of multicephalous heterolipids as chemical penetration enhancers for transdermal drug delivery

The technology of transdermal delivery nanosystems: from design and development to preclinical studies

Transdermal administration has gained much attention due to the remarkable advantages such as patient compliance, drug escape from first-pass elimination, favorable pharmacokinetic profile and prolonged release properties. However, the major limitation of these systems is the limited skin penetration of the stratum corneum, the skin's most important barrier, which protects the body from the insertion of substances from the environment. Transdermal drug delivery systems are aiming to the disruption of the stratum corneum in order for the active pharmaceutical ingredients to enter successfully the circulation. Therefore, nanoparticles are holding a great promise because they can act as effective penetration enhancers due to their small size and other physicochemical properties that will be analyzed thoroughly in this report. Apart from the investigation of the physicochemical parameters, a comparison between the different types of nanoparticles will be performed. The complexity of skin anatomy and the unclear mechanisms of penetration should be taken into consideration to reach some realistic conclusions regarding the way that the described parameters affect the skin permeability. To the best of the authors knowledge, this is among the few reports on the literature describing the technology of transdermal delivery systems and how this technology affects the biological activity.

Molecular perspective of efficiency and safety problems of chemical enhancers: bottlenecks and recent advances

Chemical penetration enhancer (CPE) is a preferred approach to improve drug permeability through the skin, due to its unique advantages of simple use and high compatibility. However, CPEs efficiency and safety problems frequently arise, which greatly restrains the further application in transdermal drug delivery systems (TDDS). To get access to the root of problems, the efficiency and safety of CPEs are reviewed especially from molecular perspectives, which include (1) the possible factors of CPEs low efficiency; (2) the possible contribution of CPEs in the evolution of safety problems such as skin irritation and allergic reaction; (3) the interactive relationship between CPEs efficiency and safety, as well as the bottlenecks of achieving their balance. More importantly, based on these, recent advances are summarized in improving efficiency or safety of CPEs, which offers a guidance of rationally selecting CPEs in future research.

Supramolecular and Macromolecular Matrix Nanocarriers for Drug Delivery in Inflammation-Associated Skin Diseases

Skin is our biggest organ. It interfaces our body with its environment. It is an efficient barrier to control the loss of water, the regulation of temperature, and infections by skin-resident and environmental pathogens. The barrier function of the skin is played by the stratum corneum (SC). It is a lipid barrier associating corneocytes (the terminally differentiated keratinocytes) and multilamellar lipid bilayers. This intricate association constitutes a very cohesive system, fully adapted to its role. One consequence of this efficient organization is the virtual impossibility for active pharmaceutical ingredients (API) to cross the SC to reach the inner layers of the skin after topical deposition. There are several ways to help a drug to cross the SC. Physical methods and chemical enhancers of permeation are a possibility. These are invasive and irritating methods. Vectorization of the drugs through nanocarriers is another way to circumvent the SC. This mini-review focuses on supramolecular and macromolecular matrices designed and implemented for skin permeation, excluding vesicular nanocarriers. Examples highlight the entrapment of anti-inflammatory API to treat inflammatory disorders of the skin.

Novel bicephalous heterolipid based self-microemulsifying drug delivery system for solubility and bioavailability enhancement of efavirenz

There is an increasing demand for new lipidic biocompatible and safe materials for self-microemulsifying drug delivery system (SMEDDS). The present work reports the synthesis, characterization, oral mucosal irritation study, and application of novel erucic acid ester of G₀-PETIM dendron based bicephalous heterolipid (BHL) as an oil phase in SMEDDS using Efavirenz (EFA), a BCS class II drug with poor water solubility and poor bioavailability. Studies were conducted to optimize EFA SMEDDS using different ratios of the BHL as oil phase and surfactant: co-surfactant weight ratios (Km). At Km (1.5), the microemulsion was spontaneously formed in water with mean globule size of 22.78 ± 0.25 nm and polydispersity index (PDI) of 0.23 ± 0.031 with high drug loading efficiency of 80.35 ± 3.1%. Standard stability tests were performed on EFA SMEDDS and the results indicated it to be highly stable. The in vitro dissolution profile of EFA SMEDDS showed >95% of the drug release within an hour and expectedly substantial enhancement in in vivo bioavailability was observed; almost 6-fold increase in bioavailability with parameters C_max 5.2 µg/mL, T_max 3 h, and AUC_(0-∞) 23.48 μg/h/mL respectively as compared the plain suspension of the drug. In conclusion, the BHL can be used effectively as an oil phase in SMEDDS to enhance solubility and bioavailability of BCS Class II drugs. Further, it holds, in general, a great promise as a new excipient for solubility and bioavailability enhancements.

Novel mono, di and tri-fatty acid esters bearing secondary amino acid ester head groups as transdermal permeation enhancers

Mono-oleate derivative (MOAPE) enhancing in vitro transdermal permeation of tenofovir.

Nanoemulgel using a bicephalous heterolipid as a novel approach to enhance transdermal permeation of tenofovir

Improvements in permeation enhancement strategies, such as nanoemulsions (NEs) and nanoemulgels (NEGs), have led to a renewed interest in transdermal drug delivery (TDD). This study aimed to investigate the potential of LLA1E, a novel dendritic permeation enhancer, as an oily phase in the development of a NEG for the TDD of tenofovir (TNF). TNF loaded NEs (TNEs) were prepared and analysed for mean globule diameter (MGD), polydispersity index (PDI), zeta potential (ZP) and morphology. NEGs of the TNEs (TNEGs) were prepared and evaluated for ex vivo transdermal permeation efficacy. The skin integrity before and after the experiments was assessed using histology and transepithelial electrical resistance (TEER). TNEs had a MGD of 129.06±3.35nm, a PDI of 0.192±0.038 and a ZP of 20.9±2.02mV, with an incorporation efficiency of 91.94±0.84%. There was no significant change is these properties after incorporating the TNEs into the hydrogel, as MGD, PDI and ZP of TNEGs were found to be 136.13±5.21nm, 0.182±0.020 and -20.9±2.08mV respectively. Ex vivo permeation studies showed that the TNEG significantly enhanced the TNF permeation by 39.65-fold, with a cumulative amount of 1866.54±108.62μgcm^-2. Histological and TEER assessments showed no permanent effects on the skin by TNEG, indicating that this novel TNEG nanosystem has the potential to translate into clinical trials as treatment alternatives for HIV/AIDs patients.

An emerging class of amphiphilic dendrimers for pharmaceutical and biomedical applications: Janus amphiphilic dendrimers

In recent years, a new class of dendrimer, known as Janus dendrimers (JDs), has attracted much attention due to their different structures and properties to the conventional symmetric forms. The broken symmetry of JDs offers the opportunity to form complex self-assembled materials, and presents new sets of properties that are presently inconceivable for homogeneous or symmetrical dendrimers. Due to their unique features, JDs have a promising future in pharmaceutical and biomedical fields, as seen from the recent interest in their application in conjugating multiple drugs and targeting moieties, forming supramolecular hydrogels, enabling micellar delivery systems, and preparing nano-vesicles, known as dendrimersomes, for drug encapsulation. The present paper is the first review, with an emphasis on various emerging applications of JDs, in the drug delivery and biomedical field reported so far. In addition, the paper describes different synthetic methods for producing JDs that can guide the design of new biocompatible forms with pharmacological activities, and that have the potential to be nano drug delivery vehicles. Furthermore, future studies to optimize the applications of JDs in drug delivery sciences and biomedical field to realize their potential to treat various disease conditions are identified and highlighted. Overall, this review identifies the current status of JDs in terms of their synthesis and applications, as well as the future research for their translation into macromolecules for clinical applications to solve health problems. It highlights the future combined efforts needed to be taken by dendrimer chemists, formulation scientist and microbiologists to develop novel antibacterials and nanomedicines from JDs.

Perspectives on Transdermal Electroporation

Transdermal drug delivery offers several advantages, including avoidance of erratic absorption, absence of gastric irritation, painlessness, noninvasiveness, as well as improvement in patient compliance. With this mode of drug administration, there is no pre-systemic metabolism and it is possible to increase drug bioavailability and half-life. However, only a few molecules can be delivered across the skin in therapeutic quantities. This is because of the hindrance provided by the stratum corneum. Several techniques have been developed and used over the last few decades for transdermal drug delivery enhancement. These include sonophoresis, iontophoresis, microneedles, and electroporation. Electroporation, which refers to the temporary perturbation of the skin following the application of high voltage electric pulses, has been used to increase transcutaneous flux values by several research groups. In this review, transdermal electroporation is discussed and the use of the technique for percutaneous transport of low and high molecular weight compounds described. This review also examines our current knowledge regarding the mechanisms of electroporation and safety concerns arising from the use of this transdermal drug delivery technique. Safety considerations are especially important because electroporation utilizes high voltage pulses which may have deleterious effects in some cases.

The Relationship between Solubility and Transdermal Absorption of Tadalafil

PURPOSE

The aim of this study was to find a relationship between drug solubility and its transdermal permeation and find the best vehicle composition to improve transdermal permeation of Tadalafil.

METHODS

Pure or binary mixtures of commonly used solvents in pharmaceutical sciences including ethanol, glycerin, N-methyl pyrrolidone (NMP), polyethylene glycol (PEG) 400 and propylene glycol (PG) were evaluated for drug solubility and transdermal delivery through the exercised rat skin employing Franz diffusion cells.

RESULTS

Tadalafil showed higher solubility in NMP compared to the other solvents. The amount of Tadalafil permeation from the pure vehicles was ranked as follow: Ethanol >glycerin >NMP>PEG 400 >PG. Furthermore, the solubility and transdermal delivery from binary mixtures of NMP and PG were higher than that obtained from pure PG, and accordingly, both increased with increasing NMP concentration in the binary solvent mixtures. The Flux values were determined as following order for Ethanol>NMP>glycerin>PG>PEG 400.

CONCLUSION

Generally, increase in Tadalafil solubility resulted in a decrease in its skin penetration rate and amount. However, NMP exhibited substantial drug skin penetration rate and amount accompanying with appropriate drug solvency. In conclusion, the results of this study introduced NMP as a solvent suitable for application in the formulation of topically applied drug delivery systems.

Novel dendritic derivatives of unsaturated fatty acids as promising transdermal permeation enhancers for tenofovir

Novel dendritic ester derivatives of unsaturated fatty acids as potential transdermal permeation enhancers.

Self-microemulsifying drug delivery system of curcumin with enhanced solubility and bioavailability using a new semi-synthetic bicephalous heterolipid: in vitro and in vivo evaluation

Curcumin SMEDDS from heterolipid E1E.

Novel oleic acid derivatives enhance buccal permeation of didanosine

The aim of this study was to explore the potential of novel oleic acid (OA) derivatives as buccal permeation enhancers for the delivery of didanosine (ddI). The OA derivatives, i.e. ester derivative (OA1E), the dicarboxylic acid derivative (OA1A) and the bicephalous dianionic surfactant (OA1ANa) were synthesized and their effects were compared to the parent OA. OA, OA1E, OA1A and OA1ANa at 1% w/w all showed potential for enhancing the buccal permeability of ddI with enhancement ratio (ER) of 1.29, 1.33, 1.01 and 1.72, respectively. OA1ANa at 1% w/w demonstrated the highest flux (80.30 ± 10.37 µg cm(-2 )h), permeability coefficient (4.01 ± 0.57 × 10(-3) cm h(-1)) and ER (1.72). The highest flux for ddI (144.00 ± 53.54 µg cm(-2 )h) was reported with OA1ANa 2% w/w, which displayed an ER of 3.09 more than that with ddI alone. At equivalent concentrations, OA1ANa (ER = 3.09) had a significantly higher permeation-enhancing effect than its parent OA (ER = 1.54). Histomorphological studies confirmed that OA1ANa at all concentrations (0.5, 2.0 and 6.0% w/w) had no adverse effects on the mucosae. Morphological changes such as vacuoles formation and increased intercellular spaces were attributed to the buccal permeation-enhancing effect of OA1ANa. This study demonstrated the potential of novel OA derivatives as buccal permeation enhancers. OA1ANa at 2% w/w was also identified as the optimal novel OA derivative to widen the pool of fatty acid derivatives as chemical permeation enhancers for buccal drug delivery.