Evaluation of Glycofurol-Based Gel as a New Vehicle for Topical Application of Naproxen

In view of the good skin tolerability, glycofurol was used as a vehicle-based gel, and its effect in the topical penetration of Naproxen (NAP) was investigated. The aims of this study were to develop a suitable gel with bioadhesive property, spreadability, and viscosity for topical anti-inflammatory effect. Three gelling and adhesive agents were examined: Carbopol 974P, Gantrez AN 119, and polyvinylpyrollidone K30. Skin permeation rates and lag times of NAP were evaluated using the Franz-type diffusion cell in order to optimize the gel formulation. The permeation rate of NAP-based gel across the excised rat skin was investigated. A significant increase in permeability parameters such as steady-state flux (J _ss), permeability coefficient (K _p), and penetration index (PI) was observed in optimized formulation containing 2% Transcutol as an permeation enhancer. From skin irritation test, it was concluded that the optimized novel glycofurol-based gel formulation was safe to be used for topical drug delivery. The developed glycofurol-based gel appeared promising for dermal and transdermal delivery of naproxen and could be applicable with water-insoluble drugs, which would circumvent most of the problems associated with drug therapy.     

Exposure to low pH is not required for penetration of mosquito cells by Sindbis virus

It is widely held that the penetration of cells by alphaviruses is dependent on exposure to the acid environment of an endosome. The alphavirus Sindbis virus replicates in both vertebrate and invertebrate cell cultures. We have found that exposure to an acid environment may not be required for infection of cells of the insect host. In this work, we investigated the effects of two agents (NH(4)Cl and chloroquine), which raise the pH of intracellular compartments (lysosomotropic weak bases) on the infection and replication of Sindbis virus in cells of the insect host Aedes albopictus. The results show that both of these agents increase the pH of endosomes, as indicated by protection against diphtheria toxin intoxication. NH(4)Cl blocked the production of infectious virus and blocked virus RNA synthesis when added prior to infection. Chloroquine, in contrast to its effect on vertebrate cells, had no inhibitory effect on infectious virus production in mosquito cells even when added prior to infection. Treatment with NH(4)Cl did not prevent the penetration of virus RNA into the cell cytoplasm or translation of the RNA to produce a precursor to virus nonstructural proteins. These data suggest that while these two drugs raise the pH of endosomes, they do not block insect cell penetration. These data support previous results published by our laboratory suggesting that exposure to an acid environment within the cell may not be an obligatory step in the process of infection of cells by alphaviruses.     

Problems in selection of topical anti-inflammatory corticosteroids

Desonide, a non-fluorinated topical corticosteroid (16-alpha-hydroxyprednisolone acetonide), is compared with its fluorinated analogue, triamcinolone acetonide, as to vasoconstriction ability and epidermal penetration rate. Clinical effectiveness of desonide is further assessed by means of a double-blind paired comparison with an accepted potent fluorinated steroid, betamethasone 17-valerate. It is demonstrated that fluorination of the steroid molecule is not necessary to achieve potent topical anti-inflammatory effect. Vasoconstriction and epidermal penetration are not enhanced by fluorination in the drugs studied.     

Drug-Eluting Fibers for HIV-1 Inhibition and Contraception

Multipurpose prevention technologies (MPTs) that simultaneously prevent sexually transmitted infections (STIs) and unintended pregnancy are a global health priority. Combining chemical and physical barriers offers the greatest potential to design effective MPTs, but integrating both functional modalities into a single device has been challenging. Here we show that drug-eluting fiber meshes designed for topical drug delivery can function as a combination chemical and physical barrier MPT. Using FDA-approved polymers, we fabricated nanofiber meshes with tunable fiber size and controlled degradation kinetics that facilitate simultaneous release of multiple agents against HIV-1, HSV-2, and sperm. We observed that drug-loaded meshes inhibited HIV-1 infection in vitro and physically obstructed sperm penetration. Furthermore, we report on a previously unknown activity of glycerol monolaurate (GML) to potently inhibit sperm motility and viability. The application of drug-eluting nanofibers for HIV-1 prevention and sperm inhibition may serve as an innovative platform technology for drug delivery to the lower female reproductive tract.     

A Sandwich Cup Method for the Penetration Assay of Antimicrobial Agents through Pseudomonas Exopolysaccharides

We developed new sandwich cup method to assay the penetration of various antimicrobial agents through Pseudomonas exopolysaccharides. Using alginate extracted from mucoid-type Pseudomonas aeruginosa and gellan gum from Pseudomonas elodea, the role of exopolysaccharides as a barrier against drug penetration was examined. The penetration of positively charged hydrophilic drugs such as aminoglycosides and polypeptides was markedly inhibited by the gels tested, but that of β-lactams, quinolones, and macrolides was not inhibited. The penetration of gentamicin was strongly influenced by the gel concentration, the solution to be used, and the presence of Ca²⁺. These results suggest that the microenvironment at the infection site could greatly influence drug penetration through biofilms in vivo.     

Conjugation of arginine oligomers to cyclosporin A facilitates topical delivery and inhibition of inflammation

Many systemically effective drugs such as cyclosporin A are ineffective topically because of their poor penetration into skin. To surmount this problem, we conjugated a heptamer of arginine to cyclosporin A through a pH-sensitive linker to produce R7-CsA. In contrast to unmodified cyclosporin A, which fails to penetrate skin, topically applied R7-CsA was efficiently transported into cells in mouse and human skin. R7-CsA reached dermal T lymphocytes and inhibited cutaneous inflammation. These data establish a general strategy for enhancing delivery of poorly absorbed drugs across tissue barriers and provide a new topical approach to the treatment of inflammatory skin disorders.     

Nonbacterial pus-forming diseases of the skin

The formation of pus as a result of an inflammatory response to a bacterial infection is well known. Not so well appreciated, however, is the fact that many other nonbacterial agents such as certain fungi, viruses and parasites may provoke pus formation in the skin. Also heat, topical applications, systemically administered drugs and some injected materials can do likewise. Numerous skin diseases of unknown etiology such as pustular acne vulgaris, pustular psoriasis and pustular dermatitis herpetiformis can have bacteriologically sterile pustules. The importance of considering nonbacterial causes of pus-forming conditions of the skin is obvious from a diagnostic and therapeutic point of view.     

<Emphasis Type="Italic">In vitro</Emphasis> susceptibility testing of <Emphasis Type="Italic">Microsporum gypseum</Emphasis> isolated from healthy cattle and soil samples against itraconazole,terbinafine, fluconazole and topical veterinarian drugs

The present study evaluated in vitro susceptibility testing of dermatophytes isolates from healthy cattle and soil samples against three antifungal agents and three topical veterinarian drugs. Itraconazole and terbinafine showed a higher in vitro fungicidal activity than fluconazole. The veterinarian drugs LEPECID^® and iodine 5% were more active in vitro than the UNGÜENTO^® spray. All drugs showed fungicidal activity against Microsporum gypseum, and they may be considered as efficient agents for the topical treatment of dermatophytoses in cattle.     

Parameters of human immunodeficiency virus infection of human cervical tissue and inhibition by vaginal virucides

Heterosexual transmission of human immunodeficiency virus (HIV) is the most frequent mode of infection worldwide. However, the immediate events between exposure to infectious virus and establishment of infection are still poorly understood. This study investigates parameters of HIV infection of human female genital tissue in vitro using an explant culture model. In particular, we investigated the role of the epithelium and virucidal agents in protection against HIV infection. We have demonstrated that the major target cells of infection reside below the genital epithelium, and thus HIV must cross this barrier to establish infection. Immune activation enhanced HIV infection of such subepithelial cells. Furthermore, our data suggest that genital epithelial cells were not susceptible to HIV infection, appear to play no part in the transfer of infectious virus across the epithelium, and thus may provide a barrier to infection. In addition, experiments using a panel of virucidal agents demonstrated differential efficiency to block HIV infection of subepithelial cells from partial to complete inhibition. This is the first demonstration that virucidal agents designed for topical vaginal use block HIV infection of genital tissue. Such agents have major implications for world health, as they will provide women with a mechanism of personal and covert protection from HIV infection.     

Multiple independent origins of a protease inhibitor resistance mutation in salvage therapy patients

With the continuing march of the AIDS epidemic and little hope for an effective vaccine in the near future, work to develop a topical strategy to prevent HIV infection is increasingly important. This stated, the track record of large scale "microbicide" trials has been disappointing with nonspecific inhibitors either failing to protect women from infection or even increasing HIV acquisition. Newer strategies that target directly the elements needed for viral entry into cells have shown promise in non-human primate models of HIV transmission and as these agents have not yet been broadly introduced in regions of highest HIV prevalence, they are particularly attractive for prophylaxis. We review here the agents that can block HIV cellular entry and that show promise as topical strategies or "virustats" to prevent mucosal transmission of HIV infection     

A Preformulation Strategy for the Selection of Penetration Enhancers for a Transungual Formulation

Onychomycosis is associated with the cutaneous fungal infection of the nail and the nail folds (skin surrounding the nail). It is therefore important to target drug delivery into the nail folds along with nail plate and the nail bed. Systematic and strategic selection of the penetration enhancers specific for the skin and the nail is discussed. Twelve penetration enhancers were screened for their ability to improve solubility, in vitro nail penetration, in vitro skin permeation, and in vitro skin penetration of the antifungal drug ciclopirox olamine. In contrast to transdermal drug delivery, the main selection criteria for skin penetration enhancer in topical drug delivery were increased drug accumulation in the epidermis and minimal permeation across the skin. Thiourea improved the solubility and nail penetration of ciclopirox olamine. It also showed enhancement in the transungual diffusion of the drug. Propylene glycol showed a 12-fold increase in solubility and 3-fold increase in epidermal accumulation of ciclopirox olamine, while minimizing the transdermal movement of the drug. Thiourea was the selected nail permeation enhancer and propylene glycol was the selected skin penetration enhancer of ciclopirox olamine. A combination of the selected enhancers was also explored for its effect on drug delivery to the nail and nail folds. The enhancer combination reduced the penetration of ciclopirox in the skin and also the permeation through the nail. The proposed preformulation strategy helps to select appropriate enhancers for optimum topical delivery and paves way towards an efficient topical formulation for passive transungual drug delivery.     

Microbicides and other topical strategies to prevent vaginal transmission of HIV

The HIV epidemic is, by many criteria, the worst outbreak of infectious disease in history. The rate of new infections is now approximately 5 million per year, mainly in the developing world, and is increasing. Women are now substantially more at risk of infection with HIV than men. With no cure or effective vaccine in sight, a huge effort is required to develop topical agents (often called microbicides) that, applied to the vaginal mucosa, would prevent infection of these high-risk individuals. We discuss the targets for topical agents that have been identified by studies of the biology of HIV infection and provide an overview of the progress towards the development of a usable agent.     

Effect of Fluidizing Agents on Paclitaxel Penetration in Cervical Cancerous Monolayer Membranes

The aim of this study was to compare modulation of paclitaxel penetration in cancerous and normal cervical monolayers by four fluidizing agents: PCPG (9:1 DPPC:PG), PCPE (9:1 DPPC:DOPE), ALEC (7:3 DPPC:PG) and Exosurf (13.5:1.5:1.0 DPPC:hexadecanol:tyloxapol). Presence of the fluidizing agents improved drug penetration significantly. PCPG and PCPE were promising penetration enhancers. PCPG 0.1% caused 3.8– and 1.7-fold higher maximum increments in surface pressure due to drug penetration, (Δπ)_max, than the control in cancerous and normal monolayers, respectively, at 20 mN/m. In cancerous monolayer at 20 mN/m, presence of 0.1%, 0.5%, 1%, 5% and 10% PCPE produced 3.4-, 5.7-, 7.4-, 9.6- and 9.8-fold higher drug penetration compared to the control monolayer without PCPE, respectively. In cancerous monolayer at 20 mN/m, PCPG and PCPE liposomes having 1 mg lipid gave 2.1 and 3.6 times higher (Δπ)_max compared to the control, respectively. Further, the liposomal drug penetration was found to be directly proportional to the liposomal lipid content. The effect of the fluidizing agents was confirmed by increased calcein release from model cervical cancer liposomes. These results may have implications in using the above biocompatible lipids and surfactants as penetration enhancers along with anticancer drugs or as carriers for liposomal formulations of anticancer drugs for improved membrane penetration.     

Development, characterization and in vivo assessment of effective lipidic nanoparticles for dermal delivery of fluconazole against cutaneous candidiasis

The nanoparticulate carrier systems as solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) have gained interest for the topical treatment of skin associated fungal infection as they facilitate the skin penetration of loaded drugs. Therefore in this study, SLNs and NLCs loaded fluconazole (FLZ) were prepared by solvent diffusion method in an aqueous system and characterized for different parameters. In addition, antifungal activity was carried out on experimentally induced cutaneous candidiasis in immunosuppressed albino rats. The results showed that SLNs and NLCs represent the respective mean particle sizes of approx. 178 and 134 nm with encapsulation efficiency of 75.7±4.94% and 81.4±3.89%, respectively. The skin-retention studies of FLZ from in vitro and in vivo experiments revealed significantly higher accumulation of drug in the case of NLCs formulation. The in vivo cumulative amount of FLZ retention from NLCs was more than 5-fold that of the plain solution, while it was 3.3-fold more in the case of an equivalent-dose application in the form of SLNs at 12h after administration. The antifungal study also confirmed the maximum therapeutic efficacy of NLCs, as the lowest number of cfu/ml was recorded. It can be concluded from this study that NLCs provide a good skin targeting effect and may be a promising carrier for topical delivery of FLZ offering the sustained release and maintain the localized effect, resulting in an effective treatment of a life-threatening cutaneous fungal infection.     

The pathogenesis of Q fever in the intratracheal infection of guinea pigs]

The intratracheal introduction of R. burnetii is the method of infection, highly similar to aerogenic infection, the most widespread route of R. burnetii infection in humans under natural conditions. This suggests that the study of the pathogenesis of Q fever resulting from the intratracheal infection of guinea pigs is highly topical. The authors have established that after the penetration of the infective agent generalized infection develops in the animals with rickettsiae accumulating mostly in the lungs and the organs of the reticuloendothelial system being affected; this infection is commonly more pronounced than that developing after the intraperitoneal inoculation of rickettsiae.     

2型单纯疱疹病毒体外感染周期的研究进展

2型单纯疱疹病毒(Herpes simplex virus type 2,HSV-2)是引起生殖器疱疹的主要病原体。生殖器疱疹主要表现为生殖器和肛周皮肤黏膜疱疹或溃疡,是一种慢性、复发性、难以治愈的性传播疾病,临床治疗多以抑制病毒复制的核苷类药物阿昔洛韦及其衍生物更昔洛韦、喷昔洛韦等为主。这些药物对缓解症状、缩短病程有一定作用,但难以达到根治的目的,长期应用易产生耐药,且对其合并症基本无效。作用于HSV-2其他感染周期的药物成为人类探索的新领域。HSV-2感染宿主细胞是一个复杂的多阶段过程,包括黏附、穿入、核转运、基因组复制、衣壳组装、子代病毒释放等多个步骤,涉及多种细胞和病毒蛋白的活性。本文对HSV-2体外感染周期详细步骤及其分子机制作一综述,以期深入了解其感染机制,并为研制作用于不同感染阶段的抗HSV-2药物提供参考。     

SYSTEMIC TOXIC REACTIONS TO LOCAL ANESTHETICS

The topical use of anesthetic agents involves an element of risk. Systemic toxic reactions are rare, but they do occur and may result in death. When a reaction occurs from a topical application, it usually progresses rapidly to respiratory and cardiovascular collapse, and thus therapy must be instituted with more haste to avoid deaths. Fatal systemic toxic reactions from topically administered anesthetic drugs are, in effect, usually not due to well informed use of the drug but to misuse owing to less than complete understanding of absorption.Emphasis is placed on the causes, prophylaxis and treatment of severe systemic toxic reactions which follow the topical application of local anesthetic drugs. If systemic toxic reactions resulting from a safe dose of a local anesthetic agent are correctly treated, there will usually follow an uneventful recovery rather than a catastrophe.     

Canine leishmaniosis--new concepts and insights on an expanding zoonosis: part two

Canine leishmaniosis is a widely spread zoonosis that is potentially fatal to humans and dogs. Infection with Leishmania infantum is considerably more prevalent than clinical disease, and infected dogs with no signs of disease might, potentially, transmit infection. Diagnosis of asymptomatic infection by serology is insufficient and PCR markedly increases its sensitivity. A new therapy exclusively for canine leishmaniosis is needed because current drugs do not reliably eliminate infection and might provoke resistance. Protection against sand-fly bites by topical insecticides is effective in reducing infection, and recent development of vaccines has indicated that prevention by vaccination is feasible. Integrated prevention with topical insecticides reducing the feeding of vectors and vaccination blocking early infection would be the basis of successful control programs.     

A rat model of diabetic wound infection for the evaluation of topical antimicrobial therapies

Diabetes mellitus is an epidemic multisystemic chronic disease that frequently is complicated by complex wound infections. Innovative topical antimicrobial therapy agents are potentially useful for multimodal treatment of these infections. However, an appropriately standardized in vivo model is currently not available to facilitate the screening of these emerging products and their effect on wound healing. To develop such a model, we analyzed, tested, and modified published models of wound healing. We optimized various aspects of the model, including animal species, diabetes induction method, hair removal technique, splint and dressing methods, the control of unintentional bacterial infection, sampling methods for the evaluation of bacterial burden, and aspects of the microscopic and macroscopic assessment of wound healing, all while taking into consideration animal welfare and the '3Rs' principle. We thus developed a new wound infection model in rats that is optimized for testing topical antimicrobial therapy agents. This model accurately reproduces the pathophysiology of infected diabetic wound healing and includes the current standard treatment (that is, debridement). The numerous benefits of this model include the ready availability of necessary materials, simple techniques, high reproducibility, and practicality for experiments with large sample sizes. Furthermore, given its similarities to infected-wound healing and treatment in humans, our new model can serve as a valid alternative for applied research.     

Fluidity enhancement: a critical factor for performance of liposomal transdermal drug delivery system

Liposomes are well known lipid carriers for drug delivery of bioactive molecules encapsulated inside their membrane. Liposomes as skin drug delivery systems were initially promoted primarily for localized effects with minimal systemic delivery. Subsequently, a novel vesicular system, transferosomes was reported for transdermal delivery with efficiency similar to subcutaneous injection. The multiple bilayered organizations of lipids applied in these vesicles structure are somewhat similar to complex nature of stratum corneal intercellular lipids domains. The incorporation of novel agents into these lipid vesicles results in the loss of entrapped markers but it is similar to fluidization of stratum corneum lipids on treatment with a penetration enhancer. This approach generated the utility of penetration enhancers/fluidizing agents in lipids vesicular systems for skin delivery. For the transdermal and topical applications of liposomes, fluidity of bilayer lipid membrane is rate limiting which governs the permeation. This article critically reviews the relevance of using different types of vesicles as a model for skin in permeation enhancement studies. This study has also been designed to encompass all enhancement measurements and analytical tools for characterization of permeability in liposomal vesicular system.