Toxic ratio

Another important aspect of transfection agents, especially for nonviral systems, was the efficiency/toxicity ratio. The CLS described by Olbrich et al. [19] showed only moderate transfection efficiencies compared with the established polymers... 

Colchicine is an antimitotic drug that is highly effective in relieving acute gout attacks but has a low benefit-toxicity ratio. When colchicine is started within the first 24 hours of an acute attack, about two-thirds of patients respond within several hours. The likelihood of success decreases substantially if treatment is delayed longer than 48 hours after symptom onset. 

Pyrethroids have low oral toxicity to mammals, and in general their insect (topical) to mammal (oral) toxicity ratio is much higher than that of the other major classes of insecticides [25]. As the reason, at least the following mechanisms are conceivable (1) negative temperature dependence - differences in body temperature between insects and mammals makes the insect nerves much more sensitive, (2) metabolic rate - insects metabolize the insecticide more slowly than mammals, and the metabolizing enzyme systems are different, and (3) differences in body size - insects will have less chance to metabolize the insecticides before reaching the target site [26]. 

In CONCLUSION, lithium is universally accepted as a mood-stabilizing drug and an effective antimanic agent whose value is limited by its poor therapeutic index (i.e. its therapeutic to toxicity ratio). Neuroleptics are effective in attenuating the symptoms of acute mania but they too have serious adverse side effects. High potency typical neuroleptics appear to increase the likelihood of tardive dyskinesia. Of the less well-established treatments, carbamazepine would appear to have a role, particularly in the more advanced stages of the illness when lithium is less effective. 

In Figs. 8-10 one can see that the distribution of average potency, selectivity, and average efficacy/toxicity ratio is exactly as one would desire. One can conclude that list 1, the highest priority list, contains the most efficacious compounds based on the degree of testing performed so far. 

Fig. 10. Distribution of average efficacy/toxicity ratio grouped by priority list. High r...

There is no information on the lethal effects of radium due to acute oral exposure. Many deaths, especially from bone cancer, have occurred in humans following long-term oral exposure to radium-226 and radium-228. As described by Rowland et al. (1978), female radium dial painters in the 1920s who "tipped" their paint brushes with their lips or tongues ingested radium in the process. The dial paint usually contained long-lived radium-226 and shorter-lived radium-228. A toxicity ratio has been developed for these isotopes it has been estimated that radium-228 is about 2.5 times as effective,... 

Many important organosulfur compounds also contain nitrogen. One such compound is thiourea, the sulfur analog of urea. Its structural formula is shown in Figure 1.19. Thiourea and phenylthiourea have been used as rodenticides. Commonly called ANTU, 1-naphthylthiourea is an excellent rodenticide that is virtually tasteless and has a very high rodent human toxicity ratio. 

Commonly called ANTU, 1-naphthylthiourea is a virtually tasteless rodenticide that has a very high rodentihuman toxicity ratio. The lethal dose to monkeys is about 4000 mg/kg. One... 

What is done to organophosphate compounds containing the P=0 group to increase their insect mammal toxicity ratios and decrease their tendency to undergo nonenzymatic hydrolysis ... 

Synthetic 13-m-retinoic acid not only inhibited the incidence but also reduced the severity of bladder neoplasms induced by the intravesical administration of MNU of female Wister-Lewis rats [113]. In an experimental model with mice treated with TV-butyl-A -(4-hydroxybutyl)-nitrosamine (OH-BBN), retinoic acid (Re5), 13-cw-retinoic acid, and retinol acetate (Re2) show chemopreventive activity. In addition, a quite large number of synthetic -alkyl amide derivatives of Re2 have a greater activity to toxicity ratio than 13-cw-retinoic acid [113]. 

Raimondo S., Montague B.J. Barron M.G. (2007) Determinants of variability in acute to chronic toxicity ratios for aquatic invertebrates and fish. Environmental Toxicology and Chemistry 26 2019-2023. 

When tests are performed on terrestrial animals, it is common to apply single (measured) doses orally, topically (i.e., applied to the skin or cuticle), or by injection into tissues or body fluids. There can be very large differences among groups of organisms and among species in their susceptibility to the toxic action of chemicals. The selective toxicity ratio (SER) is expressed in terms of the median lethal dose, and is important for the differentiation between beneficial organisms and pests ... 

The relative sensitivity of insects to pyrethrins and pyrethroids is attributable (in roughly equal proportions) to their slower metabolic disposal, to their lower body temperature, and to the inherently higher sensitivity of their target sites. Although there are few, if any, toxic actions of the pyrethroids in insects that do not have their counterpart in man, these three quantitative factors combine to give insect-mammalian toxicity ratios of 2 or 3 orders of magnitude. 

Several factors such as age, sex, diet, organ function, and drug interaction or co-medication influence drug metabolism [20], An altered biotransformation may result significantly in therapeutic failure [21] and ADRs. Therefore, it is essential to characterize drug biotransformation pathways to maximize efficacy and toxicity ratio. In this respect the two related fields namely pharmacogenetics and pharmacogenomics will have considerable potential to improve patient-specific therapy [22-24],... 

While the majority of the aniline mustards showed no hypoxia-selective cytotoxicity in the growth inhibition assay (Table 1), the corresponding 4-NOj and 3-NOj compounds (3 and 4) were more toxic to UV4 cells under hypoxic conditions, with the 4-NOj derivative showing a toxicity ratio of 3.2 (Table... 

TR Toxic ratio = ratio between the EC50,baseline and the experimental... 

QSAR predictions of basehne toxicity are relevant in the context of our model because they allow for the derivation of the toxic ratio TR (Eqs. 3, 4). They therefore constitute the basis for the classification into nonspecific (= baseline) and specific modes of toxic action [25]. We do not further consider which specific mode of toxic action might apply, but rather, in the case of specifically acting compounds, assume that the specific QSAR is parallel to the baseline QSAR with a difference in intercept given by logTR (cf Fig. 2a-c). 

Maeder V, Escher BI, Scheringer M, Elungerbiihler K (2004) Toxic ratio as an indicator of the intrinsic toxicity in the assessment of persistent, bioaccumulative, and toxic chemicals. Environ Sci Technol 38 3659-3666... 

Rhodes LE, Tii le MD, Park BK, Chu P, Verbov JL, Friedmann PS. Cimetidine improves the tiierapeutic/toxic ratio of dapsone in patients on chronic dapsone tiierapy. BrJDermatol (1995) 132, 257-62. 

The property - excess toxicity - was used to define the toxicity of chemicals (reactive or nonrective) (Lipmick, 1991). The extent of excess toxicity was determined as the toxic ratio (TR), which was calculated by the following equations 3-4 (Lipnick, 1991, Nendza Muller, 2007) ... 

On the basis of calculated and experimental values for acute toxicity, the toxicity ratio (TR) as the ratio of the calculated baseline toxicity over the experimentally determined value was calculated (Table 3). A TR-value less than one could indicate rapid hydrolysis and/or biotransformation of the parent compound by the organism to non-toxic metabolites (Aptula Roberts, 2006). 

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