Semi-mechanistic Pharmacokinetic/Pharmacodynamic model of three pegylated rHuEPO and ior®EPOCIM in New Zealand rabbits.

Marketed formulations of erythropoietin (EPO) ior®EPOCIM, MIRCERA® and two newly developed pegylated-EPO analogues (PEG-EPO 32 and 40 kDa) formulations were intravenously administered to New Zealand rabbits. A semi-mechanistic Pharmacokinetic/Pharmacodynamic (PK/PD) model describing in a simultaneous and integrated form the time course of reticulocytes, red blood cells and hemoglobin was built to account for the time course of hematopoiesis stimulation after erythropoietin administration. Data analysis was performed based on the population approach with the software NONMEM version 7.3. Erythropoietin disposition of each of the administered formulations was best described with a two compartment model and linear elimination. Different formulations show different clearance and apparent volume of distribution of the central compartment but share estimates of inter-compartmental clearance and apparent peripheral volume of distribution. A semi-mechanistic model including cell proliferation, maturation, and homeostatic regulation provided a good description of the data regardless the type of erythropoietin formulation administered. The system-, and drug-related parameters showed consistency and differed across formulations, respectively. A single IV administration of PEG-EPO 32 and 40 kDa formulations in New Zealand rabbits achieves a median change of 27% and 22% on RET levels, and of 47% and 63% on RBC and HGB levels, respectively compared to MIRCERA®. The administration of new branched PEG-chains formulations improves PK and PD properties of EPO, in terms of increasing elimination half-lives and pharmacological activity on RET, RBC and HGB compared to commercially available formulations (ior®EPOCIM and MIRCERA®).

The treatment with an anti-glycosaminoglycan antibody reduces aortic oxidative stress in a rabbit model of atherosclerosis.

Retained low-density lipoproteins (LDL) by arterial glycosaminoglycans (GAG) are more susceptible to reactive oxygen species-mediated oxidation, contributing to oxidative stress and atherosclerosis. Recently, we reported the properties of the chimeric mouse/human monoclonal antibody chP3R99-LALA to bind sulfated GAG, to inhibit LDL-chondroitin sulfate binding, and to avoid LDL oxidation in vitro. Here, we hypothesized that chP3R99-LALA treatment might reduce aortic oxidative stress in a therapeutic setting. Redox biomarkers and serum lipids were determined by spectrophotometric methods. Subcutaneous administration of five doses (100 µg) of chP3R99-LALA, after Lipofundin administration (2 mL/kg/day, i.v.) during 8 days, reduced atherosclerotic lesion development, which was not associated with a serum lipid modulation. In contrast, the treatment with chP3R99-LALA reduced (p < 0.05) malondialdehyde and protein oxidation, induced a restoration of reduced glutathione level, of the superoxide dismutase and catalase activities and of endothelial nitric oxide level. Thus, the antiatherogenic effect of chP3R99-LALA treatment seems to be associated with a reduction of aortic oxidative stress. These results contribute in understanding the molecular mechanisms associated with chP3R99-LALA atheroprotection and support the use of anti-GAG antibody-based immunotherapy as a potential tool to treat the atherosclerosis.

Kinetics of monoclonal anti-epidermal growth factor receptor antibody (IOR EGF/r3)-induced apoptosis in human carcinoma bearing nude mice

Apoptosis seems to play an important role in cancer immunotherapy outcome. We have studied the kinetic pattern of apoptosis induction in H125 human lung carcinoma xenografts after treatment with the monoclonal antibody (MAb) anti-epidermal growth factor receptor (EGFr) IOR EGF/r3. Tumor-bearing nude mice were injected intravenously with a single 8 mg/kg dose of IOR EGF/r3 and tumor specimens were taken up to 30 days post treatment. Apoptosis was measured by morphometric analysis of the histological sections at each tumor specimen over time points. The results showed a significant apoptotic response in tumors within six days after injection of this MAb reaching a peak at 20 days post treatment. The kinetics were very broad, with apoptotic cells present over the entire time-frame. However, the time course of the apoptotic index showed a significant difference to the mitotic index. Finally, the MAb-induced apoptosis was related to tumor growth delay indicating a probable arrest of cell cycle and a corresponding inhibition of tumor progression, which was corroborated by the Ki67 and proliferating cell nuclear antigen (PCNA) biomarkers.

Topical disposition of two strengths of a 125I-rhEGF jelly in rat skin wounds.

Growth factors have proved to be an effective therapeutic strategy. However, some controversies have arisen concerning their efficacy in topical wound treatments. Stabilization of epidermal growth factors at the wound site and long-lasting receptor occupancy are important factors for wound repair. This study evaluated the cumulative profiles of two jellies containing 10 or 20 microg of 125I-rhEGF per gram of jelly, in a rat full-thickness skin lesion model. The prolonged time-courses at the wound sites for both strengths compared with saline solutions previously evaluated using a similar skin lesion model are reported. It seems that these two topical formulations that provide more sustained amounts of 125I-rhEGF over the period of sampling, would probably achieve the required wound healing response in terms of cell proliferation, collagen deposition and protein synthesis. Further studies need to be developed in order to elucidate whether such an in vivo disposition pattern is consistent with an earlier and stronger promotion of wound healing events.

Monoclonal anti-EGFreceptor antibody (ior-R3) pharmacokinetic study in tumor bearing nude mice: role of the receptor-mediated endocytosis on drug clearance.

With the purpose of describing the MAb ior-R3's kinetic behavior in disease state, this paper is focused on the study of this response using a human cancer (lung carcinoma cell line, H125) bearing nude mice animal model. This MAb was administered by a single 16 mg/Kg intravenous bolus dose and the blood samples were collected at several times ranging from 0 to 72 hours for serum drug quantification. The experimental data set was best fitted using a classical two-compartment mammilary pharmacokinetic (PK) model and the corresponding PK parameters were determined. Comparatively, the analysis of the more relevant physiologically-based PK parameters showed a significant enhancing of clearance as compound with the earlier reported study on healthy mice, increasing from 0.09 to 0.19 mL/h (p<0.01). However, the corresponding distribution volumes don't seem to be altered by the tumor xenograft. We conclude that all of these evidences suggest a possible mechanism of receptor-mediated endocytosis (RME) as a major cause of this increased drug clearance which also contributed to the faster decrease of the drug disposition.

Disposition and receptor-site binding of (125)I-EGF after topical administration to skin wounds.

The rhEGF topical delivery systems have been hindered by a number of shortcomings which have led to the search of new development strategies. In this study we report the evaluation of cumulative profiles of 10, 5 and 1 microg/ml solutions of (125)I-rhEGF, in a rat full-thickness skin wound model, as well as the drug-induced modulation in the expression of the EGF receptor after lesion. The tissue-associated radioactivity, expressed as the percentage of the dose administered per grams of tissue (%D/g), peaks at 2 h after administration of all doses. (125)I-rhEGF degraded species were detected chromatographically, but no diffusion of the peptide to the surrounding skin was documented. Despite the dose, the EGF receptor expression was increased within 2 h after wounding, followed by a slow decline up to 12 h below baseline. Twelve hours after punch, differences were evident between all treated groups and control. These results demonstrate that (125)I-rhEGF saline solutions are rapidly cleared from application sites, probably by protease-driven cleavage and receptor-mediated endocytosis. Finally, we must be aware that the results herein discussed should be taken into account during the drug delivery system design in order to guarantee the necessary steady-state rhEGF levels upon wound healing process.

Monoclonal anti-epidermal growth factor receptor (ior EGF/r3) antibody pharmacokinetic studies on nude mice I: a radio-receptor analysis applied to drug serum quantification.

Due to its antagonistic properties upon ligand-epidermal growth factor receptor (EGFr) interaction, the monoclonal antibody anti-EGFr ior EGF/r3 is considered a potential therapeutic agent against several epithelium-derived tumours. This paper affords further analysis of the relevant corporal interaction of this monoclonal antibody in terms of its pharmacodynamic properties, using nude mice, following a single bolus intravenous dose administration. The radio-receptor assay allows quantification of the serum ior EGF/r3 level. The dose selection procedure, according to the Kolmogorov-Smirnov test, suggested using doses of 12.5-16 mg kg(-1) for pharmacokinetic assessments. The experimental data were best fitted to a bi-exponential function (r2 = 0.985), through the classical two-compartment open modelling approach. The model selection was corroborated by the AKAIKE information criteria, and also the SCHWARTZ and ESTRIP test were used. The estimated pharmacokinetic parameters (e.g. t 1/2 beta = 34.65 h, Vc = 2.84 mL, Vss = 4.21 mL and CL = 0.09 mL h(-1)) bear out the strategies for the evaluation of the therapeutic application of this drug. Finally, the radio-receptor analysis has provided a rationale for the proposed serum monoclonal antibody ior EGF/r3 quantification to characterize its concentration-time course.

Almidón de arroz en la preparación de tabletas. Parte II: evaluación como desintegrante / Rice starch in tablets preparation. Part II: evaluation as desintegrator

Utilizando almidón de arroz de una variedad IR-880, se prepararon tabletas modelo de teofilina, para evaluar comparativamente su comportamiento como desintegrante frente a otros agentes: almidón de maíz, metilcelulosa y mentonita. Al granulado se le midió: análisis granulométrico, densidad bruta, densidad del granulado y velocidad del flujo. A las tabletas se les midió: peso medio, desviación normal, coeficiente de variación, tiempo de desintegración, dureza, procentaje de friabilidad y velocidad de liberación del fármaco. Se establecieron los resultados comparativos del almidón de arroz, en relación con el resto de los desintegrantes empleados(AU)

Almidón de arroz en la preparación de tabletas, parte I: evaluación como aglutinante / Rice starch in tablet preparation. Part I: Its assessment as agglutinant

Se plantea que el almidón, sustancia auxiliar ampliamente utilizada en la fabricación de tabletas, en nuestras formulaciones nacionales se ha integrado como aglutinante en mezclas con gelatina. En el presente trabajo se evalúa el comportamiento aglutinante del almidón de arroz, producido nacionalmente. Se prepararon tabletas modelo de lactosa, utilizando almidón de arroz, y se comparó su comportamiento con aquéllas preparadas con gelatina, acacia y almidón de maíz(AU)

Ageing of columns of homogeneous mixed stationary phases in gas chromatography.

Chromatographic columns of homogeneous mixed phase prepared with squalane and polyethylene glycol 1540 have been subjected to an ageing process of about 1700 hours at 100 degrees C followed by a similar period of time at 120 degrees C. Little change is observed at the lower temperature, while at 120 degrees C, a selective loss of the most volatile component of the mixture seems to occur, producing changes in the values of the retention indices obtained.