High Safety Margin (high + safety_margin)

Distribution by Scientific Domains

Selected Abstracts

Anticonvulsant profile and teratogenicity of 3,3-dimethylbutanoylurea: A potential for a second generation drug to valproic acid

EPILEPSIA, Issue 7 2008
Jakob Avi Shimshoni
Summary Purpose: The purpose of this study was to evaluate the anticonvulsant activity and teratogenic potential of branched aliphatic acylureas represented by isovaleroylurea (IVU), pivaloylurea (PVU) and 3,3-dimethylbutanoylurea (DBU), as potential second-generation drugs to valproic acid (VPA). Methods: The anticonvulsant activity of IVU, PVU, and DBU was determined in mice and rats utilizing the maximal electroshock seizure (MES) and the pentylenetetrazole (scMet) tests. The ability of DBU to block electrical-, or chemical-induced seizures was further examined in three acute seizure models: the psychomotor 6 Hz model, the bicuculline and picrotoxin models and one model of chronic epilepsy (i.e., the hippocampal kindled rat model). The induction of neural tube defects (NTDs) by IVU, PVU, and DBU was evaluated after i.p. administration at day 8.5 of gestation to a mouse strain highly susceptible to VPA-induced teratogenicity. The pharmacokinetics of DBU was studied following i.v. administration to rats. Results: DBU emerged as the most potent compound having an MES-ED50of 186 mg/kg (mice) and 64 mg/kg (rats) and an scMet-ED50of 66 mg/kg (mice) and 26 mg/kg (rats). DBU underwent further evaluation in the hippocampal kindled rat (ED50= 35 mg/kg), the psychomotor 6 Hz mouse model (ED50= 80 mg/kg at 32 mA and ED50= 133 mg/kg at 44 mA), the bicuculline- and picrotoxin-induced seizure mouse model (ED50= 205 mg/kg and 167 mg/kg, respectively). In contrast to VPA, DBU, IVU, and PVU did not induce a significant increase in NTDs as compared to control. DBU was eliminated by metabolism with a half-life of 4.5 h. Conclusions: DBU's broad spectrum and potent anticonvulsant activity, along with its high safety margin and favorable pharmacokinetic profile, make it an attractive candidate to become a new, potent, and safe AED. [source]

Organotin(IV) tryptophanylglycinates: potential non-steroidal antiinflammatory agents; crystal structure of dibutyltin(IV) tryptophanylglycinate

Mala Nath
Abstract Diorganotin(IV) derivatives of tryptophanylglycine (H2Trp,Gly) with general formula R2Sn(Trp,Gly), where R = Me, n -Bu, Ph and n -Oct, and triorganotin(IV) derivatives R,3 Sn(HTrp,Gly) where R, = Me, n -Bu and Ph, have been synthesized and structurally characterized in the ,solid state as well as in solution on the basis of various spectroscopic techniques, viz. FT-IR, multinuclear 1H, 13C and 119Sn NMR, 119Sn Mössbauer and single crystal X-ray diffraction. These investigations suggest that tryptophanylglycine in R2Sn(Trp,Gly) acts as dianionic tridentate coordinating through carboxylate oxygen [C(O)O,], amino nitrogen (NH2) and N,peptide, while in the case of R,3 Sn(HTrp,Gly), the ligand acts as monoanionic bidentate coordinating through C(O)O, and NH2. This is further confirmed by the single-crystal X-ray structure of n -Bu2Sn(Trp,Gly) which shows that two butyl groups and peptide nitrogen (N,peptide) are in the equatorial positions, while the two axial positions are occupied by the carboxylic oxygen [C(O)O,] and the amino nitrogen (NH2) atom from the same ligand molecule in the distorted trigonal,bipyramidal geometry around tin. The anti-inflammatory (using the carrageenan-induced paw edema bioassay in rats), cardiovascular activities and acute toxicity (LD50) of some of these compounds have been examined. All of the studied R2Sn(Trp,Gly) and Ph3Sn(HTrp,Gly) exhibit very high anti-inflammatory activities comparable to that of phenylbutazone along with high safety margin (LD50 > 400 mg kg,1) with no side effects on the cardiovascular system. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Antiepileptic drug discovery: lessons from the past and future challenges

H. Klitgaard
Historically, most antiepileptic drugs (AEDs) have been discovered either by serendipity, or the screening of compounds using acute seizure models. However, an increasing understanding of the molecular mechanisms underlying epileptogenesis has led to more rational approaches to drug discovery, which have focused on either enhancing inhibitory , -amino butyric acid (GABA)-ergic, or antagonizing excitatory glutamatergic, neurotransmission. Unfortunately, AEDs generated using such strategies have poor efficacy and safety profiles, as they interfere with normal cell processes, while ignoring the complex underlying pathophysiology of epilepsy. Recently, however, the use of new epilepsy models has led to the discovery of levetiracetam, an AED with a truly unique mechanism of action, devoid of anticonvulsant activity in normal animals, but with potent seizure suppression in genetic and kindled chronic epilepsy models, and an unusually high safety margin. The recent identification of brivaracetam and seletracetam, which optimize this unique mechanism of action, may further improve the medical management of epilepsy. The experience with levetiracetam, brivaracetam and seletracetam reveals that new experimental epilepsy models can detect AEDs possessing a unique mechanism of action and thereby target the future challenge of providing clinicians novel additions to the current armamentarium of AEDs. [source]

Effective poxvirus removal by sterile filtration during manufacture of plasma derivatives,

A. Berting
Abstract As a consequence of the September 2001 terrorist events, programs to protect against further such acts including potentially the use of biological warfare agents have been launched in the USA and elsewhere. As part of these initiatives, Vaccinia virus was procured for the pre-emptive vaccination of key personnel against smallpox as well as population-wide protection after an eventual exposure. The introduction of this live virus into a population at a relatively large scale represents a theoretical challenge for the safety of the blood supply, and potentially for plasma for fractionation. To strengthen further the demonstration of safety margins for plasma derived products against Vaccinia virus, the capacity of sterile filtration procedures to remove the virus was investigated. An infectivity assay for the Vaccinia virus strain which represents the majority of smallpox vaccine stocks available currently was used to investigate the potential removal of this virus by sterile filtration processes during the manufacture of plasma derivatives. Vaccinia virus behaves as predicted based on its size, i.e., an artificially added virus load is removed about 10,000-fold by the sterile filtration procedures tested. As the current investigation covered a range of different protein concentrations, filter materials and filters from different manufacturers, the results obtained are considered to be widely applicable. The current investigation supports further the high safety margins of plasma derivatives against any potential Vaccinia virus content of plasma for fractionation. As the large size is a general feature of Orthopox viruses, the results would also provide assurance against poxviruses identified more recently, for example, Monkeypox virus. J. Med. Virol. 75:603,607, 2005. © 2005 Wiley-Liss, Inc. [source]

Virus susceptibility of Chinese hamster ovary (CHO) cells and detection of viral contaminations by adventitious agent testing

Andreas Berting
Abstract Biopharmaceuticals are of increasing importance in the treatment of a variety of diseases. A remaining concern associated with their production is the potential introduction of adventitious agents into their manufacturing process, which may compromise the pathogen safety of a product and potentially cause stock-out situations for important medical supplies. To ensure the safety of biological therapeutics, regulatory guidance requires adventitious agent testing (AAT) of the bulk harvest. AAT is a deliberately promiscuous assay procedure which has been developed to indicate, ideally, the presence of any viral contaminant. One of the most important cell lines used in the production of biopharmaceuticals is Chinese hamster ovary (CHO) cells and while viral infections of CHO cells have occurred, a systematic screen of their virus susceptibility has never been published. We investigated the susceptibility of CHO cells to infection by 14 different viruses, including members of 12 families and representatives or the very species that were implicated in previously reported production cell infections. Based on our results, four different infection outcomes were distinguished, based on the possible combinations of the two factors (i) the induction, or not, of a cytopathic effect and (ii) the ability, or not, to replicate in CHO cells. Our results demonstrate that the current AAT is effective for the detection of viruses which are able to replicate in CHO cells. Due to the restricted virus susceptibility of CHO cells and the routine AAT of bulk harvests, our results provide re-assurance for the very high safety margins of CHO cell-derived biopharmaceuticals. Biotechnol. Bioeng. 2010;106: 598,607. © 2010 Wiley Periodicals, Inc. [source]