Sistema de administración de fármacos autoemulsionante: una estrategia para mejorar la biodisponibilidad oral

Objetivo: La vía oral siempre ha sido la ruta preferida de administración de fármacos en muchas enfermedades y hasta hoy es la primera forma investigada en el desarrollo de nuevas formas de dosificación. El principal problema en las formulaciones de fármacos orales es la baja y errática biodisponibilidad, lo que resulta fundamentalmente por la escasa solubilidad en agua, con lo que plantean problemas en su formulación. Para la administración terapéutica de los grupos activos lipófilos (BCS clase II drogas), las formulaciones a base de lípidos están teniendo cada vez más atención. Métodos: Con ese objetivo, a partir de los sitios web de PubMed, HCAplus, Thomson, y sus registros se utilizaron como fuentes principales para llevar a cabo la búsqueda de los artículos de investigación más importantes publicados sobre el tema. A continuación, la información fue analizada cuidadosamente, poniendo de relieve los resultados más importantes en la formulación y desarrollo de sistemas de administración de fármacos auto-emulsionante micro, así como su actividad terapéutica. Resultados: El sistema de administración de fármacos autoemulsionante (SMEDDS) ha ganado más atención debido a la mejorada que permite la reducción de la biodisponibilidad oral en dosis, los perfiles temporales más consistentes de la absorción del fármaco, la orientación selectiva de fármaco (s) hacia la ventana de absorción específica en el tracto gastrointestinal, y la protección del fármaco (s) desde el entorno poco receptivo en el intestino. Conclusiones: Este artículo proporciona una visión completa de SMEDDS como un enfoque prometedor para abordar eficazmente el problema de moléculas poco solubles.Aim: Oral route has always been the favorite route of drug administration in many diseases and till today it is the first way investigated in the development of new dosage forms. The major problem in oral drug formulations is low and erratic bioavailability, which mainly results from poor aqueous solubility, thereby pose problems in their formulation. For the therapeutic delivery of lipophilic active moieties (BCS class II drugs), lipid based formulations are inviting increasing attention. Methods: To that aim, from the web sites of PubMed, HCAplus, Thomson, and Registry were used as the main sources to perform the search for the most significant research articles published on the subject. The information was then carefully analyzed, highlighting the most important results in the formulation and development of self-micro emulsifying drug delivery systems as well as its therapeutic activity. Results: Self-emulsifying drug delivery system (SMEDDS) has gained more attention due to enhanced oral bio-availability enabling reduction in dose, more consistent temporal profiles of drug absorption, selective targeting of drug(s) toward specific absorption window in GIT, and protection of drug(s) from the unreceptive environment in gut. Conclusions: This article gives a complete overview of SMEDDS as a promising approach to effectively deal with the problem of poorly soluble molecules

HER-2/neu and CD117 (c-kit) overexpression in patients with pesticide exposure and extensive stage small cell lung carcinoma (ESSCLC)

BACKGROUND: The rate of detection of HER-2/neu and CD117 (c-kit) overexpression in small cell lung cancer (SCLC) has varied widely; between 5–35% and 21–70% respectively. METHODS: To evaluate the relationship between pesticide exposure and HER-2/neu and CD117 overexpression in extensive stage SCLC (ESSCLC), we identified patients with ESSCLC and assessed pesticide exposure using a predetermined questionnaire. An exposure index (hours/day × days/year × years) ≥ 2400 hours was considered as 'exposed.' HER-2/neu overexpression was evaluated on archival tissue using the DAKO Hercep test, and CD117 testing was performed using immunohistochemistry (A4052 polyclonal antibody). RESULTS: 193 ESSCLC patients were identified. Pesticide exposure data could be obtained on 174 patients (84 females and 109 males) with a mean age of 68.5 years. 53/174 (30.4%) revealed HER-2/neu overexpression. 54/174 (31.03%) specimens showed CD117 overexpression by IHC. On multivariate analysis, HER-2/neu overexpression was associated with diminished survival (p < 0.001). In comparison, CD117 expression did not have an adverse prognostic value (p = 0.025). 41/53 (77.4%) patients with HER-2/neu overexpression and 47/121 (38.8%) patients without overexpression had exposure to pesticides (odds ratio: 5.38; p < 0.01). Among the cohort tested for CD117, 29/54 (53.7%) patients with CD117 overexpression and 59/120 (49.2%) patients without CD117 overexpression had pesticide exposure (odds ratio: 1.18; p = 0.12). CONCLUSION: Pesticide exposure affects HER-2/neu but not CD117 overexpression. Future studies are needed to determine specific pesticide(s)/pesticide components that are responsible for HER-2/neu overexpression in ESSCLC, and to validate our findings in other solid tumors that overexpress HER-2/neu

Angiotensin II Up-Regulates Angiotensin I-Converting Enzyme (ACE), but Down-Regulates ACE2 via the AT1-ERK/p38 MAP Kinase Pathway

The recent discovery of the angiotensin II (Ang II)-breakdown enzyme, angiotensin I converting enzyme (ACE) 2, suggests the importance of Ang II degradation in hypertension. The present study explored the signaling mechanism by which ACE2 is regulated under hypertensive conditions. Real-time PCR and immunohistochemistry showed that ACE2 mRNA and protein expression levels were high, whereas ACE expression levels were moderate in both normal kidney and heart. In contrast, patients with hypertension showed marked ACE up-regulation and ACE2 down-regulation in both hypertensive cardiopathy and, particularly, hypertensive nephropathy. The inhibition of ACE2 expression was shown to be associated with ACE up-regulation and activation of extracellular regulated (ERK)1/2 and p38 mitogen-activated protein (MAP) kinases. In vitro, Ang II was able to up-regulate ACE and down-regulate ACE2 in human kidney tubular cells, which were blocked by an angiotensin II (AT)1 receptor antagonist (losartan), but not by an AT2 receptor blocker (PD123319). Furthermore, blockade of ERK1/2 or p38 MAP kinases by either specific inhibitors or a dominant-negative adenovirus was able to abolish Ang II-induced ACE2 down-regulation in human kidney tubular cells. In conclusion, Ang II is able to up-regulate ACE and down-regulate ACE2 expression levels under hypertensive conditions both in vivo and in vitro. The AT1 receptor-mediated ERK/p38 MAP kinase signaling pathway may be a key mechanism by which Ang II down-regulates ACE2 expression, implicating an ACE/ACE2 imbalance in hypertensive cardiovascular and renal damage