Quality and stability of oral extemporaneous formulations developed from commercial tablets containing spironolactone / Desenvolvimento e estudo de estabilidade de formulações extemporâneas de uso oral a partir de comprimidos comerciais contendo espironolactona

The purpose of this study was to develop extemporaneous liquid pharmaceutical formulations from commercial tablets containing spironolactone and to assess their stability for use in children or adults with difficulty in swallowing. The content and stability of spironolactone in the tablets, as well as in water, 1.5% carboxymethylcellulose (CMC) or simple syrup dispersions were determined by high performance liquid chromatography (HPLC) analysis on a C18 silica column (250 mm ? 4.6 mm ? 5 ?m), with a mobile phase of methanol:water (75:25 v/v), flowing at 1 mL/min, and UV detection at 240 nm. The extemporaneous formulations were tested over a 35-day period at 8, 27, and 40 ºC. Drug content in the aqueous dispersion was far lower than expected, with significant fluctuations at all temperatures, owing to rapid sedimentation. The content proved adequate in aqueous 1.5% CMC dispersion at 27 ºC, with undesirable variations at the other temperatures. The syrup-based dispersion remained stable at all three temperatures, with suitable drug content and no significant variability. No degradation products were observed in any of the formulations. The syrup-based dispersion is easy to prepare, self-preserving, stable, palatable, offering satisfactory drug content per dose, and can therefore be recommended as an extemporaneous formulation for enhancing treatment adherence and effectiveness...

O objetivo desse trabalho foi desenvolver e avaliar a estabilidade de formas farmacêuticas líquidas extemporâneas, a partir de amostras comerciais (comprimidos), contendo espironolactona, para que possam ser empregadas em pacientes pediátricos ou adultos com dificuldade de deglutição. A metodologia empregada para a análise do teor e da estabilidade do fármaco espironolactona nos comprimidos e nas dispersões utilizando água, carboximetilcelulose (CMC) 1,5% e xarope simples foi a Cromatografia Líquida de Alta Eficiência (CLAE), utilizando coluna de sílica C18 (250 mm x 4,6 mm x 5 μm), fluxo de 1 mL/min, comprimento de onda 240 nm e fase móvel metanol:água (75:25 v/v). As formulações extemporâneas foram analisadas durante 35 dias nas temperaturas de 8, 27 e 40 ºC. A dispersão aquosa apresentou teor muito abaixo do esperado, com variações significativas em todas as temperaturas, devido à rápida sedimentação. A dispersão aquosa de CMC 1,5% apresentou teor adequado na temperatura de 27 ºC com variações indesejadas nas demais temperaturas. A dispersão de xarope simples apresentou-se estável nas três temperaturas, com teor adequado e sem variações significativas. Não foi observado produto de degradação em nenhuma das formulações propostas. Por ser de fácil preparação, autoconservante, estável e de sabor agradável, a dispersão de xarope simples é a formulação extemporânea recomendada, pois garante teor satisfatório por dose e, portanto, favorece aumento à adesão e à eficácia do tratamento...

High airborne PM2.5 chlorine concentrations link to diabetes surge in Portugal.

Since 1995 airborne particles have been sampled near Lisbon and analysed by PIXE at ITN. On the Summer of 2004 extremely high concentrations of 14 microg/m(3) of chlorine in PM2.5 were determined in a week average sample. Later in 2004 and in 2005 similar events occurred. A 12 year database of PIXE data on airborne elemental concentrations (1995 to 2006) compiled on 2007 was then analysed for PM2.5 chlorine concentrations above 1 microg/m(3), and showed that the number of this type of events per year is increasing since 1995 up until the present. A quest for time coincident abnormal health data reports was carried out and revealed a 30% raise in diabetes mellitus incidence from 2003 to 2004 followed by a 20% raise from 2004 to 2005. After a first short publication at the XIth Int. PIXE Conference in 2007 (Reis et al., 2007a) the problem remained live. Taking into account new insights into the problem, recently published data, and biomonitoring data that were previously not considered, it was possible to establish a highly probable link between the abnormally high values of PM2.5 chlorine measured in the Lisbon area and the surge in diabetes mellitus incidence in Portugal in 2004 and 2005. Data, reasoning, possible mechanisms and conclusions regarding this link are reported in the present paper.

Enhanced binding of low and high density lipoproteins to human adipocyte plasma membranes: effects of temperature and proteases.

The specific binding of 125I-labelled low density lipoprotein ([125I]LDL to human adipocyte plasma membranes was higher at 37 than at 0 degree C. Prior treatment of membranes with pronase had no effect on LDL binding measured at 0 degree C but consistently stimulated binding at 37 degrees C. Plasmin was similar to pronase in enhancing LDL-specific binding, but thrombin was not as effective. 125I-labelled high density lipoprotein ([125I]HDL2) specific binding to human adipocyte plasma membranes was similarly sensitive to temperature and pronase treatment. Addition of the protease inhibitor aprotinin in the adipocyte membrane binding assay significantly reduced [125I]LDL binding at 37 degrees C (p less than 0.05), suggesting the involvement of a protease activity intrinsic to the lipoproteins and (or) membranes. These data demonstrate that both LDL and HDL binding in human adipocyte plasma membranes can be "up-regulated" by specific proteolytic perturbations in a temperature-dependent manner.

Characterization of high density lipoprotein binding to human adipocyte plasma membranes.

Freshly isolated human adipocytes showed specific uptake of 125I-labeled human high density lipoprotein (HDL2 and HDL3), a portion of which could be released by subsequent incubation with excess unlabeled ligand. To study the mechanism of HDL binding, sucrose gradient-purified adipocyte plasma membranes were incubated with radioiodinated lipoprotein particles under equilibrium conditions in the absence (total binding) or presence (nonspecific binding) of 100-fold excess unlabeled ligand. Specific binding of HDL2 and HDL3, calculated by subtracting nonspecific from total binding, was Ca++ independent, unaffected by EDTA, and not abolished by pronase treatment of the membranes. Modification of HDL3 by reductive methylation or cyclohexanedione treatment also failed to affect its binding to adipocyte plasma membranes. High salt concentration (200 mM NaCl) inhibited specific binding of HDL2 and HDL3 but had no effect on LDL binding. A significant portion of 125I-HDL2 or 125I-HDL3 binding was consistently inhibited by adding excess unlabeled LDL, but this inhibition was incomplete as compared with a similar molar excess of unlabeled HDL2 or HDL3. The role of apoproteins (apo) in HDL binding to adipocyte membranes was examined by comparing binding of HDL2 and HDL3 isolated from normal, abetalipoproteinemic (abeta) and apo E-deficient (apo E0) plasma. Specific binding was observed with all normal and mutant HDL particles. Furthermore, a significant portion (61-78%) of abeta-HDL2, apo E0-HDL2, and apo E0-HDL3 binding was inhibited by adding 100-fold excess of unlabeled low density lipoproteins (LDL). The cross-competition of LDL and HDL binding was confirmed by the ability of normal, abeta, and apo E0-HDL2 to completely inhibit 125I-LDL binding. These data suggest that HDL binding is independent of apo E and that the responsible apoprotein(s) of HDL complete with LDL-apo B for binding to the same or closely related site in the adipocyte plasma membrane. Normal and apo E0-HDL3 binding was also completely inhibited by normal HDL2, which suggested that HDL2 and HDL3 probably bind to the same site. Scatchard analysis of normal HDL2, normal HDL3, and apo E0-HDL3 binding data best fitted a one-component binding profile with similar equilibrium dissociation constants (40-96 nM). HDL3 binding was found to be effectively inhibited by anti-human apo AI or anti-human apo AII, but not by anti-human apo B antisera. This binding was also unaffected by monoclonal anti-human apo B or E antibodies known to inhibit binding of apo B or apo E containing lipoprotein to the LDL receptor of cultured fibroblasts. These findings, taken together, suggest that human fat cells possess HDL binding sites with apo AI and /or apo AII specificity. The significant but partial inhibition of HDL2 and HDL3 binding by LDL along with the complete inhibition of LDL binding by HDL2 and HDL3 tends to exclude a single binding site that interacts both lipoproteins and favors the interpretation that LDL and HDL particles bind to multiple recognition sites or to different conformation of the same lipoprotein binding domain on the human fat cell.

Characterization of low density lipoprotein binding to human adipocytes and adipocyte membranes.

125I-labeled low density lipoprotein (LDL) binding to purified plasma membranes prepared from freshly isolated human adipocytes was saturable, specific, and displaceable by unlabeled ligand. The maximum specific binding capacity measured at saturating concentrations of 125I-LDL was 1.95 +/- 1.17 micrograms of LDL bound/mg of membrane protein (mean +/- S.D., n = 16). In contrast to cultured fibroblasts, specific binding of LDL to adipocyte membranes was calcium-independent, was not affected by EDTA or NaCl, and was not destroyed by pronase. Plasma membranes purified directly from homogenized adipose tissue also showed calcium-independent LDL specific binding (0.58 +/- 0.33 micrograms of LDL bound/mg of membrane protein, mean +/- S.D. n = 11). Specific binding, internalization, and degradation of 125I-methylated LDL was demonstrated in isolated adipocytes and competition experiments showed that native and methylated LDL interacted with adipocytes through some common recognition mechanism(s). Compared to native LDL, specific binding of methylated LDL to adipocyte membranes was significantly reduced (43%), indicating that interaction of LDL with adipocyte was dependent in part on the lysine residues of apolipoprotein B. LDL binding to adipocyte plasma membranes was also competitively inhibited by human high density lipoprotein subfractions HDL2 and HDL3. Thus, LDL metabolism in mature adipocytes appears to be regulated by mechanisms distinctly different from a variety of cultured mesenchymal cells. In addition, the ability of adipocytes to bind, internalize, and degrade significant amounts of methylated LDL supports the view that adipose tissue is involved in the metabolism of modified lipoproteins in vivo.