Exploration of skin permeation mechanism of frusemide with proniosomes

The present study explored the transdermal permeation enhancing mechanism of non-ionic surfactant vesicles (proniosomes) of frusemide across rat skin. Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), activation energy and histological examination were carried out to study the mode of action of the optimized proniosome formulations PGS [Span 40:soyalecithin:cholesterol (4.5:4.5:1)] and PGD [Span 40:dicetylphosphate:cholesterol (4.5:4.5:1)]. The IR spectra showed a prominent decrease in peak areas and heights of CH2 stretchings but did not show shift of these peaks and shift in amide bands. DSC studies also confirmed the IR findings. It was concluded that the proniosomes disrupted the lipid bilayer by extracting the lipids thereby creating pathways for drug penetration. The significant decrease in activation energy for frusemide permeation across rat skin indicated the SC lipid bilayers were significantly disrupted (p<0.05). Histological investigations were carried out. Disruption and extraction of lipid bilayers as distinct voids and empty spaces were visible in the epidermal region. Overall, our findings suggested that proniosomal formulations offer a promising means for non-invasive delivery of frusemide, especially due to their ability to modulate drug transfer and serve as non-toxic permeation enhancers.

Nanocarrier for the transdermal delivery of an antiparkinsonian drug

The purpose of the present study was to investigate the potential of nanoemulsions as nanodrug carrier systems for the percutaneous delivery of ropinirole. Nanoemulsions comprised Capryol 90 as the oil phase, Tween 20 as the surfactant, Carbitol as the cosurfactant, and water as an external phase. The effects of composition of nanoemulsion, including the ratio of surfactant and cosurfactant (Smix) and their concentration on skin permeation, were evaluated. All the prepared nanoemulsions showed a significant increase in permeation parameters such as steady state flux (Jss) and permeability coefficient (Kp) when compared to the control (p<0.01). Nanoemulsion composition (NEL3) comprising ropinirole (0.5% w/w), Capryol 90 (5% w/w), Smix 2:1 (35% w/w), and water (59.5% w/w) showed the highest flux (51.81+/-5.03 microg/cm2/h) and was selected for formulation into nanoemulsion gel. The gel was further optimized with respect to oil concentration (Capryol 90), polymer concentration (Carbopol), and drug content by employing the Box-Behnken design, which statistically evaluated the effects of these components on ropinirole permeation. Oil and polymer concentrations were found to have a negative influence on permeation, while the drug content had a positive effect. Nanoemulsion gel showed a 7.5-fold increase in skin permeation rate when compared to the conventional hydrogel. In conclusion, the results of the present investigation suggested a promising role of nanoemulsions in enhancing the transdermal permeation of ropinirole.

Chemical penetration enhancers: a patent review

BACKGROUND

Ever since transdermal drug delivery came into existence, it has offered great promises, although most of them are yet to be fulfilled owing to some intrinsic restrictions of the transdermal route. On the positive side, transdermal drug delivery systems present advantages including non-invasiveness, prolonged therapeutic effect, reduced side effects, improved bioavailability, better patient compliance and easy termination of drug therapy. The greatest hindrance in the percutaneous delivery is the obstruction property of the stratum corneum, the outermost layer of the skin, in addition to usual problems such as skin binding, skin metabolism, cutaneous toxicity and prolonged lag times.

OBJECTIVE

This paper reviews investigations on the feasibility and application of penetration enhancers as described in recent patents, which help in the selection of a suitable sorption promoter(s) for enhanced delivery of medicaments through the skin.

METHOD

The patents granted under various categories of penetration enhancers have been discussed including fatty acids, terpenes, fatty alcohol, pyrrolidone, sulfoxides, laurocapram, surface active agents, amides, amines, lecithin, polyols, quaternary ammonium compounds, silicones, alkanoates and so on.

CONCLUSION

Scores of promising chemicals have been harnessed for their skin permeation promoting capacity as mentioned earlier. In future, many more chemicals and putative enhancers are likely be documented and patented.

Emerging Significance of Flavonoids as P-Glycoprotein Inhibitors in Cancer Chemotherapy

Chemotherapy forms the mainstay of cancer treatment particularly for patients who do not respond to local excision or radiation treatment. However, cancer treatment by drugs is seriously limited by P-glycoprotein (P-gp) associated multi-drug resistance (MDR) in various tumor cells. On the other hand, it is now widely recognized that P-gp also influences drug transport across various biological membranes. P-gp transporter is widely present in the luminal surface of enterocytes, biliary canalicular surface of hepatocytes, apical surface of proximal tubular cells of kidney, endothelial cells of blood brain barrier, etc. thus affecting absorption, distribution, metabolism and excretion of xenobiotics. Clinical significance of above mentioned carrier is appreciated from the fact that more than fifty percent of existing anti-cancer drugs undergo inhibitable and saturable P-gp mediated efflux. Consequently, there is an increasing trend to optimize pharmacokinetics, enhance antitumour activity and reduce systemic toxicity of existing anti-cancer drugs by inhibiting P-gp mediated transport. Although a wide variety of P-gp inhibitors have been discovered, research efforts are underway to identify the most appropriate one. Flavonoids (polyphenolic herbal constituents) form the third generation, non-pharmaceutical category of P-gp inhibitors. The effects produced by some of these components are found to be comparable to those of well-known P-gp inhibitors verapamil and cyclosporine. Identification of effective P-gp modulator among herbal compounds have an added advantage of being safe, thereby making them ideal candidates for bioavailability enhancement, tissue-penetration (e.g. blood brain barrier (BBB)), decreasing biliary excretion and multi-drug resistance modulating agents. The dual effects, i.e. P-gp modulation and antitumor activity, of these herbal derivatives may synergistically act in cancer chemotherapy. This paper presents an overview of the investigations on the feasibility and application of flavonoids as P-gp modulators for improved efficacy of anti-cancer drugs like taxanes, anthracyclines, epipodophyllotoxins, camptothecins and vinca alkaloids. The review also focuses on flavonoid-drug interactions as well as the reversal activity of flavonoids useful against MDR. In addition, the experimental models which could be used for investigation on P-gp mediated efflux are also discussed.

Dental therapeutic systems

The recognition of periodontal diseases as amenable to local antibiotherapy has resulted in a paradigmatic shift in treatment modalities of dental afflictions. Moreover the presence of antimicrobial resistance, surfacing of untoward reactions owing to systemic consumption of antibiotics has further advocated the use of local delivery of physiologically active substances into the periodontal pocket. While antimicrobials polymerized into acrylic strips, incorporated into biodegradable collagen and hollow permeable cellulose acetate fibers, multiparticulate systems, bio-absorbable dental materials, biodegradable gels/ointments, injectables, mucoadhesive microcapsules and nanospheres will be more amenable for direct placement into the periodontal pockets the lozenges, buccoadhesive tablets, discs or gels could be effectively used to mitigate the overall gingival inflammation. Whilst effecting controlled local delivery of a few milligram of an antibacterial agent within the gingival crevicular fluid for a longer period of time, maintaining therapeutic concentrations such delivery devices will circumvent all adverse effects to non- oral sites. Since the pioneering efforts of Goodson and Lindhe in 1989, delivery at gingival and subgingival sites has witnessed a considerable progress. The interest in locally active systems is evident from the patents being filed and granted. The present article shall dwell in reviewing the recent approaches being proffered in the field. Patents as by Shefer, et al. US patent, 6589562 dealing with multicomponent biodegradable bioadhesive controlled release system for oral care products, Lee, et al. 2001, US patent 6193994, encompassing a locally administrable, biodegradable and sustained-release pharmaceutical composition for periodontitis and process for preparation thereof and method of treating periodontal disease as suggested by Basara in 2004via US patent 6830757, shall be the types of intellectual property reviewed and presented in the current manuscript.

Emerging role of microemulsions in cosmetics

Microemulsions represent a promising carrier system for cosmetic active ingredients due to their numerous advantages over the existing conventional formulations. They are capable of solubilizing both hydrophilic and lipophilic ingredients with relatively higher encapsulation. There is growing recognition of their potential benefits in the field of cosmetic science in addition to the drug delivery. They are now being widely investigated for preparing personal care products with superior features such as having improved product efficiency, stability or appearance. They are well suited for the preparation of various cosmetic products for use as moisturizing and soothing agents, as sunscreens, as antiperspirants and as body cleansing agents. They are also valuable for use in hair care compositions which ensure a good conditioning of the hair as well as good hair feel and hair gloss. They have also found application in after shave formulations which upon application to the skin provide reduced stinging and irritation and a comforting effect without tackiness. These newer formulations elicit very good cosmetic attributes and high hydration properties with rapid cutaneous penetration which may accentuate their role in topical products. These smart systems are also suitable for perfuming purposes where minimum amount of organic solvents is required, such as for perfuming skin or hair. This article highlights the recent innovations in the field of microemulsion technology as claimed by different patents which can bring unique products with great commercial prospects in a very competitive and lucrative global cosmetic market.

Microemulsions: a novel approach to enhanced drug delivery

Microemulsions are isotropic, thermodynamically stable transparent (or translucent) systems of oil, water and surfactant, frequently in combination with a cosurfactant with a droplet size usually in the range of 20-200 nm. They can be classified as oil-in-water (o/w), water-in-oil (w/o) or bicontinuous systems depending on their structure and are characterized by ultra low interfacial tension between oil and water phases. These versatile systems are currently of great technological and scientific interest to the researchers because of their potential to incorporate a wide range of drug molecules (hydrophilic and hydrophobic) due to the presence of both lipophilic and hydrophilic domains. These adaptable delivery systems provide protection against oxidation, enzymatic hydrolysis and improve the solubilization of lipophilic drugs and hence enhance their bioavailability. In addition to oral and intravenous delivery, they are amenable for sustained and targeted delivery through ophthalmic, dental, pulmonary, vaginal and topical routes. Microemulsions are experiencing a very active development as reflected by the numerous publications and patents being granted on these systems. They have been used to improve the oral bioavailability of various poorly soluble drugs including cyclosporine and paclitaxel as professed by Hauer et al., US patent 7235248, and Gao et al., US patent 7115565, respectively. Furthermore, they can be employed for challenging tasks such as carrying chemotherapeutic agents to neoplastic cells and oral delivery of insulin as diligently described by Maranhao, US patent 5578583 and Burnside et al., US patent 5824638 respectively. The recent commercial success of Sandimmune Neoral (Cyclosporine A), Fortovase (Saquinavir), Norvir (Ritonavir), etc. also reflects the tremendous potential of these newer drug therapeutic systems. A critical evaluation of recent patents claiming different approaches to improve the drug delivery is the focus of the current review.

Inverse targeting of diclofenac sodium to reticuloendothelial system-rich organs by sphere-in-oil-in-water (s/o/w) multiple emulsion containing poloxamer 403

Sphere-in-oil-in-water (s/o/w) multiple emulsions containing diclofenac sodium were prepared by gelatinization of inner aqueous phase. A further modified version (s/o/wp) of s/o/w was formulated by adding 5.0% w/v poloxamer 403 to the external aqueous phase during the second step of emulsification in order to affect the adsorptive coating on the surface (s/o/wp). The inverse targeting of reticuloendothelial system (RES) rich organs was compared with a non reticuloendothelial system after intravenous administration of s/o/w multiple emulsion (treatment I) and poloxamer containing s/o/wp multiple emulsion (treatment II). The amount of diclofenac sodium in the plasma and various organs was measured to elucidate the effect of inverse targeting to RES and targeting to other tissues in terms of the incorporated drug. After i.v. administration, the half life (34.65 vs.16.26 h) and apparent volume of distribution of diclofenac sodium (2815 vs. 1671.5 ml/kg) were significantly higher in treatment II than in treatment I. It is concluded that the amount of drug in RES rich organs (spleen, liver) were significantly lower than the values in non-RES organs such as lungs, inflammatory tissue (synovial fluid) in treatment II than in treatment I.

Multiple Emulsions: An Overview

Multiple emulsions are complex polydispersed systems where both oil in water and water in oil emulsion exists simultaneously which are stabilized by lipophillic and hydrophilic surfactants respectively. The ratio of these surfactants is important in achieving stable multiple emulsions. Among water-in-oil-in-water (w/o/w) and oil-in-water-in-oil (o/w/o) type multiple emulsions, the former has wider areas of application and hence are studied in great detail. Formulation, preparation techniques and in vitro characterization methods for multiple emulsions are reviewed. Various factors affecting the stability of multiple emulsions and the stabilization approaches with specific reference to w/o/w type multiple emulsions are discussed in detail. Favorable drug release mechanisms and/or rate along with in vivo fate of multiple emulsions make them a versatile carrier. It finds wide range of applications in controlled or sustained drug delivery, targeted delivery, taste masking, bioavailability enhancement, enzyme immobilization, etc. Multiple emulsions have also been employed as intermediate step in the microencapsulation process and are the systems of increasing interest for the oral delivery of hydrophilic drugs, which are unstable in gastrointestinal tract like proteins and peptides. With the advancement in techniques for preparation, stabilization and rheological characterization of multiple emulsions, it will be able to provide a novel carrier system for drugs, cosmetics and pharmaceutical agents. In this review, emphasis is laid down on formulation, stabilization techniques and potential applications of multiple emulsion system.