P-glycoprotein (P-gp), a transmembrane permeability glycoprotein, is a member of ATP binding cassette (ABC) super family that functions specifically as a carrier mediated primary active efflux transporter. It is widely distributed throughout the body and has a diverse range of substrates. Several vital therapeutic agents are substrates to P-gp and their bioavailability is lowered or a resistance is induced because of the protein efflux. Hence P-gp inhibitors were explored for overcoming multidrug resistance and poor bioavailability problems of the therapeutic P-gp substrates. The sensitivity of drug moieties to P-gp and vice versa can be established by various experimental models in silico, in vitro and in vivo. Ever since the discovery of P-gp, the research plethora identified several chemical structures as P-gp inhibitors. The aim of this review was to emphasize on the discovery and development of newer, inert, non-toxic, and more efficient, specifically targeting P-gp inhibitors, like those among the natural herb extracts, pharmaceutical excipients and formulations, and other rational drug moieties. The applications of cellular and molecular biology knowledge, in silico designed structural databases, molecular modeling studies and quantitative structure-activity relationship (QSAR) analyses in the development of novel rational P-gp inhibitors have also been mentioned. Glicoproteína-p (P-gp), uma glicoproteína de transmembrana permeável, é um membro da superfamília (ABC) de cassete de gene de ligação de ATP que funciona especificamente como um carreador mediado pelo transportador de efluxo ativo primário. É amplamente distribuído por todo o corpo e apresenta uma gama diversificada de substratos. Diversos agentes terapêuticos vitais são substratos para P-gp e sua biodisponibilidade é reduzida ou a resistência é induzida devido ao efluxo de proteínas. Portanto, os inibidores da P-gp foram explorados para a superação da resistência a múltiplas drogas e problemas de biodisponibilidade deficiente dos substratos terapêuticos da P-gp. A sensibilidade das moléculas da droga à P-gp e vice-versa, pode ser estabelecida por vários modelos experimentais in silico, in vitro e in vivo. Desde a descoberta da P-gp, diversas pesquisas identificaram várias estruturas químicas como inibidores da P-gp. O objetivo deste presente estudo foi o de enfatizar a descoberta e desenvolvimento de inibidores mais novos, inertes, atóxicos e mais eficazes, visando especificamente os da P-gp, como aqueles entre os extratos vegetais, excipientes e formulações farmacêuticas, e outras moléculas racionais de droga. As aplicações do conhecimento de biologia celular e molecular, bancos de dados estruturais in silico, estudos de modelagem molecular e análises da relação quantitativa estrutura-atividade (QSAR) no desenvolvimento de novos inibidores racionais da P-gp também foram mencionados.Unitermos: Glicoproteína-p. Resistência a múltiplas drogas. Cluster de diferenciação 243. Esfingolipídeos. Inibidores competitivos.

These results suggest that niosomal methotrexate gel is more efficacious than placebo and marketed methotrexate gel.

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Transdermal drug delivery has attracted much attention as an alternative to intravenous and oral methods of delivery. But the main barrier is stratum corneum. Terpenes classes of chemical enhancers are used in transdermal formulations for facilitating penetration of drugs. The aim of the study is to evaluate terpenes as skin penetration enhancers and correlate its relationship with permeation and lipophilicity. In this study, alfuzosin hydrochloride (AH) hydrogels were prepared with terpenes using Taguchi orthogonal array experimental design. The formulations contained one of eight terpenes, based on their lipophilicity (log P 2.13-5.36). The percutaneous permeation was studied in rat skin using diffusion cell technique. Flux, cumulative amount, lag time and skin content of AH were measured over 24 hours and compared with control gels. Nerolidol with highest lipophilicity (log P 5.36 ± 0.38) showed highest cumulative amount (Q24) of 647.29 ± 18.76 μg/cm2 and fluxrateof 28.16 ± 0.64 μg/cm2/hour. It showed decreased lag time of 0.76 ± 0.15 hours. Fenchone (2.5%) (log P 2.13 ± 0.30) produced the longest lag time 4.8 ± 0.20 hours. The rank order of enhancement effect was shown as nerolidol > farnesol > limonene > linalool > geraniol > carvone > fenchone > menthol. Lowest skin content was seen with carvone. Increase in lipophilicity of terpenes showed increase in flux, cumulative amount (Q24), and enhancement ratio which was significant with P < 0.000. But lag time was decreased and no correlation was found between lipophilicity and skin content. Histological studies showed changes in dermis which can be attributed to disruption of lipid packing of stratum corneum due to effect of nerolidol within lipid lamellae. It was found that small alcoholic terpenes with high degree of unsaturation enhance permeation of hydrophilic drugs, liquid terpenes enhance better than solid terpenes and terpenes with high lipophilicity are good penetration enhancers.

Vaccines are the preparations given to patients to evoke immune responses leading to the production of antibodies (humoral) or cell-mediated responses that will combat infectious agents or noninfectious conditions such as malignancies. Alarming safety profile of live vaccines, weak immunogenicity of sub-unit vaccines and immunization, failure due to poor patient compliance to booster doses which should potentiate prime doses are few strong reasons, which necessitated the development of new generation of prophylactic and therapeutic vaccines to promote effective immunization. Attempts are being made to deliver vaccines through carriers as they control the spatial and temporal presentation of antigens to immune system thus leading to their sustained release and targeting. Hence, lower doses of weak immunogens can be effectively directed to stimulate immune responses and eliminate the need for the administration of prime and booster doses as a part of conventional vaccination regimen. This paper reviews carrier systems such as liposomes, microspheres, nanoparticles, dendrimers, micellar systems, ISCOMs, plant-derived viruses which are now being investigated and developed as vaccine delivery systems. This paper also describes various aspects of “needle-free technologies” used to administer the vaccine delivery systems through different routes into the human body.

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The objective of the present study is to explore the efficient chemical penetration enhancer among the various enhancers available in overcoming the stratum corneum barrier in transdermal delivery of Alfuzosin hydrochloride (AH). The different enhancers were incorporated in 2% Carbopol gel which was selected as a control and evaluated by in vitro diffusion studies through dialysis membrane and permeation through the rat abdominal skin using Keshary-Chien diffusion cells. All the enhancers increased the release rate through the dialysis membrane when compared with control except oleic acid which decreased the release rate but showed maximum solubility of the drug. Among the various enhancers Transcutol 20% and tween-20 (2%) showed the highest cumulative amount (Q 24) of 702.28 ± 6.97 μg/cm2 and 702.74 ± 7.49 μg/cm2, respectively. A flux rate of 31.08 ± 0.21 μg/cm2/hr by Transcutol 20% and 30.38 ± 0.18 μg/cm2/hr by tween-20 (2%) was obtained. Transcutol 20% showed decreased lag time of 0.13 ± 0.05 hr. The lowest skin content of 342.33 ± 5.30 μg/gm was seen with oleic acid 2.5%. Maximum enhancement of flux by 3.94-fold was obtained with transcutol 20%. Primary skin irritation studies were performed with rabbit. Histopathological studies of transcutol 20% showed marked changes such as degeneration and infiltration of mononuclear cells in dermis indicating the effect of transcutol on the skin. Among the different enhancers transcutol is efficient in enhancing transdermal delivery of AH.