Native-state solubility and transfer free energy as predictive tools for selecting excipients to include in protein formulation development studies

In the present report, two formulation strategies, based on different aggregation models, were compared for their ability to quickly predict which excipients (cosolutes) would minimize the aggregation rate of an immunoglobulin G1 monoclonal antibody (mAb-1) stored for long term at refrigerated and room temperatures. The first formulation strategy assumed that a conformational change to an aggregation-prone intermediate state was necessary to initiate the association process and the second formulation strategy assumed that protein self-association was instead controlled by the solubility of the native state. The results of these studies indicate that the stabilizing effect of excipients formulated at isotonic concentrations is derived from their ability to solubilize the native state, not by the increase of protein conformational stability induced by their presence. The degree the excipients solvate the native state was determined from the apparent transfer free energy of the native state from water into each of the excipients. These values for mAb-1 and two additional therapeutic antibodies correlated well to their long-term 4°C and room temperature aggregation data and were calculated using only the literature values for the apparent transfer free energies of the amino acids into the various excipients and the three-dimensional models of the antibodies.     

Active compounds release from semisolid dosage forms

The aim of this paper is to review all the aspects of the in vitro release testing (IVRT) from semisolid dosage forms. Although none of the official dissolution methods has been specified for use with semisolid dosage forms, their utility for assessing release rates of drugs from semisolid dosage forms has become a topic of considerable interest. One can expect to overcome such complexity in the future, when the official “Topical and Transdermal Drug Products—Product Performance Tests” will be published in an issue of the Pharmacopeial Forum. Many factors such as type of the dissolution medium, membrane, temperature, and speed have an influence on the mechanism and kinetics of the release testing from gels, creams, and ointments; therefore, those parameters have been widely discussed.     

The multidrug transporter P-glycoprotein in pharmacoresistance to antiepileptic drugs

This review provides an overview of the knowledge on P-glycoprotein (P-gp) and its role as a membrane transporter in drug resistance in epilepsy and drug interactions. Overexpression of P-gp, encoded by the ABCB1 gene, is involved in resistance to antiepileptic drugs (AEDs), limits gastrointestinal absorption and brain access of AEDs. Although several association studies on ABCB1 gene with drug disposition and disease susceptibility are completed to date, the data remain unclear and incongruous. Although the literature describes other multidrug resistance transporters, P-gp is the main extensively studied drug efflux transporter in epilepsy.     

Function of the hypothalamo-neurohypophysial system in rats with myocardial infarction is modified by melatonin

BackgroundPineal and melatonin interactions with the hypothalamo-neurohypophysial system are well documented. In addition, vasopressin and oxytocin secretion are known to be part of the neuroendocrine response to chronic heart failure evoked by myocardial infarction. The present study was undertaken to evaluate the possible regulatory role of melatonin in the vasopressin and oxytocin release in rats with myocardial infarction.MethodsThe vasopressin and oxytocin content of the hypothalamus and neurohypophysis, as well as their plasma levels, were radioimmunoassayed in sham-operated or pinealectomized rats with left coronary artery ligation (CAL)-evoked myocardial infarction as well as under melatonin treatment.ResultsInfarcted rats demonstrated increased vasopressin and oxytocin plasma levels, but melatonin restricted the release of both neurohormones in these rats. Experimental myocardial infarction in pinealectomized rats caused a distinct inhibition of vasopressin release but intensified oxytocin secretion. In pinealectomized rats substituted with melatonin, pineal indole amine was seen to inhibit oxytocin release and stimulate vasopressin secretion.Conclusions(i) CAL-induced myocardial infarction is the reason for increased hypothalamo-neurohypophysial system activity in rats; melatonin plays the role of inhibitory neuromodulator of vasopressin and oxytocin release in this state. (ii) Myocardial infarction evoked in pinealectomized rats is characterized by the inversion of the neurohumoral response pattern in respect of inhibited vasopressin release. (iii) Melatonin stimulates vasopressin (but decreases oxytocin) release in pinealectomized rats with myocardial infarction.     

The effect of serotonin 5HT1B receptor ligands on amphetamine self-administration in rats

A number of data indicate that serotonin (5-HT) 5-HT(1B) receptor ligands affect the behavioral effects of psychostimulants. In the present study we examined effects of the selective 5-HT(1B) receptor antagonist N-[3-[3-(dimethylamino)ethoxy]-4-methoxyphenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)-[1,1'-biphenyl]-4-carboxamide hydrochloride (SB 216641) and the agonist 5-propoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-pyrrolo[3,2-b]pyridine hydrochloride (CP 94253) on amphetamine self-administration in rats. SB 216641 administered in doses of 2.5-7.5 mg/kg did not affect the self-administration of amphetamine injected in unit doses of 0.06 or 0.12 mg/kg/infusion. On the other hand, CP 94253 administered in doses of 2.5 or 5 mg/kg attenuated amphetamine self-administration, yet the effect of 2.5 mg/kg of the agonist was fairly weak and significant only in case of a higher unit dose of the psychostimulant. The inhibitory effect of CP 94253 administered in a dose of 5mg/kg on the self-administration of amphetamine injected in a unit dose of 0.06 mg/kg/infusion was significantly reduced by SB 216641 administrated in a dose of 7.5 mg/kg. These results indicate that tonic activation of 5-HT(1B) receptors is not involved in the self-administration of amphetamine, while pharmacological stimulation of these receptors attenuates this behavioral phenomenon.     

Y-26763: ATP-sensitive K+ channel activation and the inhibition of insulin release from human pancreatic beta-cells

The effect of Y-26763 [(-)-(3S,4R)-4-(N-acetyl-N-hydroxyamino)-6-cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-3-ol], a novel ATP-sensitive K(+) (K(ATP)) channel activator, was tested on insulin secretion from human pancreatic islets in vitro. Y-26763 was able to inhibit both glucose- and tolbutamide-induced insulin secretion from islets as assessed by radioimmunoassay. The mechanism for inhibition of insulin secretion was characterised using patch clamp electrophysiology on dispersed human pancreatic beta-cells which express K(ATP) channels comprised of Kir6.2 and SUR1, and the NES2Y human beta-cell line, transfected with Kir6.2DeltaC26. Y-26763 activated K(ATP) channels in a reversible manner with a similar activity to diazoxide. This required the presence of hydrolysable nucleotides and appeared to be mediated by interaction of Y-26763 with SUR1 since: (a) tolbutamide was able to reverse the actions of Y-26763 and (b) Y-26763 failed to activate Kir6.2DeltaC26 in the absence of SUR1. We conclude that Y-26763-induced inhibition of insulin release is dependent upon the activation of K(ATP) channels in human beta-cells.     

Changing defaults in biobank research could save lives too

In an effort to increase the amount of organs available for transplantation, many countries have implemented presumed consent for organ donation. Presuming a wish to contribute to medical advances through biobank research on previously taken tissue samples could similarly improve health and wellbeing. In this article we analyze common arguments for and against presumed consent for organ donation and assess their relevance in the context of biobank research. In spite of obvious differences between biobank research and organ transplantation the cases for implementing presumption of a positive attitude appear quite analogous. It has repeatedly been shown that a majority of the general population supports these projects and selecting informed consent as the default position decreases the amount of organs and samples available and thus reduces the prospect of promoting health. We conclude that instead of presuming that individuals do not wish to contribute to the advancement of healthcare through biobank research on previously taken samples, ethics committees should presume that they do.     

The potential contribution of small-scale intervention projects in the field to the national health information system for HIV and sexually transmitted infections: a case study of a multilevel intervention in Guatemala

Objective  

Guatemala’s efforts to fight sexually transmitted infections and HIV/AIDS are compromised by the lack of timely and accurate data. The strengthening of the national Monitoring and Evaluation system is key for a better understanding of the epidemics and the formulation of effective public health responses. This study assessed how health service providers in resource-poor countries can contribute indicators to national health authorities.     

Investigations and design of pyridine-2-carboxylic acid thiazol-2-ylamide analogs as methionine aminopeptidase inhibitors using 3D-QSAR and molecular docking

Methionine amino peptidases (MetAPs) are metalloproteases that remove co-translational N-terminal methionine from nascent polypeptide chains. Due to their essential role in protein synthesis, MetAPs are considered as potential targets for antibacterial drugs. In the present work, three-dimensional quantitative structure–activity relationship (3D-QSAR) studies were carried out on a series of pyridine-2-carboxylic acid thiazol-2-ylamide-based MetAP inhibitors using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques. The models were developed using 30 training set molecules. The optimum CoMFA and CoMSIA models obtained for the training set were statistically significant with cross-validated correlation coefficients (q ²) of 0.799 and 0.704 and conventional correlation coefficients (r ²) of 0.989 and 0.954, respectively. These inhibitors were docked into MetAP active site. The CoMFA and CoMSIA field contour maps correlate well with the structural characteristics of the binding pocket of MetAP active site. Using the knowledge of structure–activity relationship and receptor–ligand interactions from 3D-QSAR model and the docked complexes, four new pyridine-2-carboxylic acid thiazol-2-ylamide analogs were designed. These analogs exhibit significantly better predicted activity than the reported molecules. The present work has implications for the development of novel antibiotics as potent MetAP inhibitors.