Predicting Human Intestinal Absorption Using Chromatography and Spectroscopy

New drug entities (NDE) are constantly being developed with most of them intended for oral administration. For this reason, there is a need to estimate their absorption in order to save time and money that would be lost if the drug enters the clinical stage and is then found to exhibit poor absorption. For many years, the use of animals was the most abundant method for studying pharmacokinetics to predict parameters such as intestinal absorption. However, these methods are time consuming, and expensive as well as being ethically unfavourable. As a result, developing other methods to evaluate a drug’s pharmacokinetics is crucial. The aim of this work was to develop in vitro methods for estimation of human intestinal absorption (%HIA) to replace the use of the aforementioned, less favourable methods involving the use of animals. Among the developed methods in this thesis is a unique type of chromatography known as micellar liquid chromatography (MLC) using biosurfactants such as bile salts as a mobile phase. Furthermore, studies investigated the effect of a change in the stationary phase in addition to investigating the effect of the change in temperature on the elution of the analysed compounds. It was found that R2PRED for the developed MLC methods was in the range of 43.3 % - 91.12 %. Another developed method was a spectrophotometric method based on the use of the solubilising effects of bile salts, as well as their binding to compounds. Therefore, two spectrophotometric methods were developed, a solubilisation method and a double reciprocal method, and used in the prediction of %HIA. It was found that the solubilisation method had a better predictability for %HIA than that of the double reciprocal method where R2PRED was found to be 82.32 % and 61.90 % respectively. Finally, a permeation method was developed using the ability of NaDC to form a hydrogel under specific conditions and applying the investigated drugs in an infinite dose to the prepared hydrogels. This facilitated the determination of permeability coefficients (Kp) that were then used in the prediction of %HIA using the obtained model. The two developed permeation methods were found to have close values of R2PRED for % HIA where R2PRED of the permeation method using flow through cells was found to be 79.8 % while that of the permeation method using Franz cells was found to be 79.67 %. In summary, this work reports several unique models for the in vitro prediction of human intestinal absorption, potentially removing the need for animal testing to predict %HIA

Oxidant-antioxidant balance in childhood asthma

Background: Asthmatic patients generate reactive oxygen species impairing the antioxidant defense system and creating a state of oxidative stress in asthmatics. Objectives: Determination of the oxidant - antioxidant status in asthmatic children, by measuring the activities of antioxidant enzymes; superoxide dismutases (SOD) and glutathione peroxidases (Gpx) and estimating plasma level of malondialdehyde (MDA) as an index of lipid peroxidation, to find a relation between antioxidant levels and the severity of asthma and the early response to treatment. Methods: This study included 60 children; group (1): 40 asthmatic children and group (2): 20 apparently healthy children as a control group. The following were measured in all the children; plasma level of (MDA), erythrocytes (SOD) and (Gpx) (in asthmatic children two samples were taken; the first during acute attack and the second after 48 hours of treatment). Results: Significant lower erythrocyte antioxidant enzymes activities and higher malondialdehyde was found in asthmatic children compared to the control group, either before or after receiving treatment. In asthmatics, MDA was significantly decreasing and SOD was significantly increasing with treatment. MDA was significantly higher, while SOD was significantly lower with the severity of asthma either before or after receiving treatment. A significant negative correlation was observed between MDA with both of SOD and Gpx, in acute asthmatic attacks. A significant positive correlation was detected between the activities of SOD and Gpx enzymes. Conclusion: Acute asthma leads to a considerable oxidative stress that is indicated by the high level of malondialdehyde and low level of antioxidant enzymes.Keywords: bronchial asthma, superoxide dismutases (SOD), glutathione peroxidases (Gpx), malondialdehyde (MDA), antioxidantsEgypt J Pediatr Allergy Immunol 2013;11(1):35-4

Predicting human intestinal absorption in the presence of bile salt with micellar liquid chromatography

Understanding intestinal absorption for pharmaceutical compounds is vital to estimate bioavailability and therefore the in vivo potential of a drug. This study considers the application of micellar liquid chromatography (MLC) to predict passive intestinal absorption with a selection of model compounds. MLC is already known to aid prediction of absorption using simple surfactant systems however, with this study the focus was on the presence of a more complex, bile salt surfactant, as would be encountered in the in vivo environment. As a result, MLC using a specific bile salt has been confirmed as an ideal in vitro system to predict the intestinal permeability for a wide range of drugs, through the development of a quantitative partition-absorption relationship. MLC offers many benefits including environmental, economic, time-saving and ethical advantages compared with the traditional techniques employed to obtain passive intestinal absorption values

Interleukin-12 levels in Egyptian children with type 1 diabetes mellitus

Background: Type 1 diabetes mellitus (T1DM), arising through a complex interaction of immune, genetic and environmental factors, results from autoimmune destruction of insulin-producing β cells. Cytokines are critical to the function of both innate and adaptive immune responses. Interleukin-12 p40 production influences T cell response, and may therefore be important in T1DM pathogenesis. Objective: to study the changes in IL12 levels in children with T1DM. Study design: fifty T1DM children among those attending diabetes clinic at Zagazig University hospitals, were included in the study. They were 27 males and 23 females (mean age, 9.19 ± 3.3 years). Thirty age and sex matched healthy children were serving as a control group. All children were subjected to full history taking, physical examination, complete blood count (CBC), random blood sugar, glycated hemoglobin (HBA1C) and serum IL-12 levels assessed by ELISA. Results: Diabetic children had significantly higher white blood cell count, HBA1C, and IL12 levels than healthy children. While there was no effect of gender on IL12 levels, there were significant increase in IL12 levels in newly diagnosed cases, those with higher body mass index and those who had the poorest glycemic control. Conclusion: type 1 diabetes is associated with elevation of IL-12 levels. This association is more evident in both newly diagnosed and poorly controlled patients indicating a relevant role of IL-12 in the pathogenesis of the disease.Keywords: Type 1 Diabetes Mellitus, Interleukin 12, EgyptEgypt J Pediatr Allergy Immunol 2013;11(1):41-4

Prediction of human intestinal absorption using micellar liquid chromatography with an aminopropyl stationary phase

The extent of human intestinal absorption (HIA) for a drug is considered to be an important pharmacokinetic parameter which must be determined for orally administered drugs. Traditional experimental methods relied upon animal testing and are renowned for being time consuming, expensive as well as being ethically unfavourable. As a result, developing alternative methods to evaluate a drug's pharmacokinetics is crucial. Micellar liquid chromatography (MLC) is considered to be one of these methods that can replace the use of animals in prediction of HIA. In this study, the combination of an aminopropyl column with the biosurfactant sodium deoxycholate (NaDC) bile salt were used in the experimental determination of micelle-water partition coefficients (log Pmw) for a group of compounds. Multiple linear regression (MLR) was then used for the prediction of HIA using the experimentally determined log Pmw along with other molecular descriptors leading to the construction of a model equation of R2= 85 % and a prediction power represented by R2Pred. =72 %. The use of MLC with an aminopropyl column in combination with NaDC was found to be a good method for the prediction of human intestinal absorption, providing data for a far wider range of compounds compared with previous studies

Allergic bronchopulmonary aspergillosis as a cause of bronchial asthma in children

Background: Allergic bronchopulmonary aspergillosis (ABPA) occurs in patients with asthma and cystic fibrosis. When aspergillus fumigatus spores are inhaled they grow in bronchial mucous as hyphae. It occurs in non immunocompromised patients and belongs to the hypersensitivity disorders induced by Aspergillus. Objective: To diagnose cases of allergic bronchopulmonary aspergillosis among asthmatic children and define the association between the clinical and laboratory findings of aspergillus fumigatus (AF) and bronchial asthma. Methods: Eighty asthmatic children were recruited in this study and divided into 50 atopic and 30 non-atopic children. The following were done: skin prick test for aspergillus fumigatus and other allergens, measurement of serum total IgE, specific serum aspergillus fumigatus antibody titer IgG and IgE (AF specific IgG and IgE) and absolute eosinophilic count. Results: ABPA occurred only in atopic asthmatics, it was more prevalent with decreased forced expiratory volume at the first second (FEV1). Prolonged duration of asthma and steroid dependency were associated with ABPA. AF specific IgE and IgG were higher in the atopic group, they were higher in Aspergillus fumigatus skin prick test positive children than negative ones .Wheal diameter of skin prick test had a significant relation to the level of AF IgE titer. Skin prick test positive cases for aspergillus fumigatus was observed in 32% of atopic asthmatic children. Conclusion: ABPA occurs in 1/3 of atopic asthmatic children and is related to the duration and severity of asthma.Keywords: Aspergillosis, bronchial asthma, childrenEgypt J Pediatr Allergy Immunol 2012;10(2):95-10

Relation between Interleukin 8 and Bronchial Asthma in Children: Review Article

Background: Asthma is a frequent respiratory condition to treat. A persistent airway inflammation characterizes this frequent form of pulmonary disease. Immune responses are triggered by cytokines and chemokines produced by airway epithelial cells. Human bronchial epithelial cells secrete IL-8 in response to the presence of interleukin-4 (IL-4) and interleukin-13, both of which are increased in asthmatics. There are two receptors for IL-8, the IL-8 receptor alpha (also known as CXCR1) and beta (also known as the IL-8 RB, CXCR2). IL8 is a potent chemotactic cytokine that activates inflammatory cells by recruiting mast cells, mononuclear phagocytes T lymphocytes, and neutrophils to the site of inflammation. Objective: To determine the relationship between IL8 and bronchial asthma in children. Conclusion: The assessment of IL8 levels in pediatric asthmatic patients is a useful biomarker reflecting the status of asthma and also to glucocorticoids and treatment responses

Formation of a bile salt-drug hydrogel to predict human intestinal absorption

The unique character of bile salts to self-assemble into hydrogels in the presence of halide salts was exploited in this work to facilitate the prediction of human intestinal absorption (%HIA) for a set of 25 compounds. This was achieved by firstly incorporating each compound separately within the process of gel formation to create a series of gel-drug membranes. Scanning Electron Microscopy (SEM) analysis of the freeze-dried samples of the blank bile salt hydrogels and drug loaded bile salt hydrogels indicated a unique microstructure made of a network of intertwined fibrils. Drug-loaded sodium deoxycholate (NaDC) hydrogels were then utilised as the donor phase to study permeability using flow-through and static diffusion cells. The resulting values of the release-permeability coefficient (Kp) were then analysed, along with other molecular descriptors, for the prediction of human intestinal absorption (%HIA) using multiple linear regression (MLR). Overall, when comparing predicted values (using the systems presented in this study) with known literature values, it can be seen that both methods (i.e. using static and flow through cells) had good predictability with R2PRED. values of 79.8 % and 79.7 % respectively. This study therefore proposes a novel, accurate and precise way to predict human intestinal absorption for compounds of pharmaceutical interest using a simple in vitro permeation system. It is important to develop alternatives to the current methods used in prediction of HIA which are expensive and time consuming or include the use of animals. Therefore, the proposed method in this study being economic and time saving provides superiority over these current methods and suggests the possibility of its use as an alternate to such methods for prediction of HIA

The use of bile salt micelles for the prediction of human intestinal absorption

Human intestinal absorption (HIA) will dictate biopharmaceutical performance through its influence on absorption, distribution, metabolism, and elimination and can vary significantly depending upon the nature of the compound under consideration. In this study, an in vitro assay method is proposed for the prediction of HIA through the measurement of drug solubility in an aqueous phase containing micellar bile salt, namely sodium deoxycholate. A series of twenty compounds, displaying a range of physicochemical properties and known HIA values, were analyzed using UV spectroscopy to determine a solubilization ratio for each compound. A micelle/water partition coefficient (Kxm/a) was calculated and then used to develop an equation through simple linear regression; logit HIA = −0.919 + 0.4618 logKxm/a (R2 = 0.85). From this equation, a value for % HIA was determined which compared well with literature. Furthermore, 4 additional drugs were then analyzed using the developed equation and found to match well with literature, confirming the suitability of the method. Using a simple, economic, and robust UV bile salt assay allows prediction of HIA and avoids many of the disadvantages of other techniques, such as animal-based methods