Lethal dose curve

If the response of interest is death or lethality, the response versus log dose curve of Figure 2-7 is called a lethal dose curve. For comparison purposes the dose that results in 50%... 

Figure 2-8 The various types of response vs. log dose curves. ED, effective dose TD, toxic dose LD, lethal dose. For gases, LC (lethal concentration) is used.

Finally, if the response to the agent is toxic (an undesirable response that is not lethal but is irreversible, such as liver or lung damage), the response-log dose curve is called the toxic dose, or TD curve. 

The more classical approach to assess the presence of marine biotoxins in seafood is the in vivo mouse bioassay. It is based on the administration of suspicious extracted shellfish samples to mice, the evaluation of the lethal dose and the toxicity calculation according to reference dose response curves, established with reference material. It provides an indication about the overall toxicity of the sample, as it is not able to differentiate among individual toxins. This is a laborious and time-consuming procedure the accuracy is poor, it is nonspecific and generally not acceptably robust. Moreover, the mouse bioassay suffers from ethical implications and it is in conflict with the EU Directive 86/609 on the Protection of Laboratory Animals. Despite the drawbacks, this bioassay is still the method of reference for almost all types of marine toxins, and is the official method for PSP toxins. 

Quantal dose-response curves based on all-or-none responses. A. Relationship between the dose of phenobarbital and the protection of groups of rats against convulsions. B. Relationship between the dose of phenobarbital and the drug s lethal effects in groups of rats. ED50, effective dose, 50% LD50, lethal dose, 50%. 

Papers describing the destruction by radiation of approximately 150 microorganisms have been published. Since the work was carried out under varying conditions and with a wide range of objectives it is not prudent to draw quantitative comparisons between lethal curves reported by different scientists. In general, under conditions of normal aeration in buffer or saline solutions the mean lethal doses shown in Table VI may be taken as representative. 

It relates the pharmacologically effective dose to the toxic or lethal dose (Fig. 2.8). The therapeutic index gives some indication of the safety of the compound in use, as the larger the ratio, the greater the relative safety. However, as already indicated, simple comparison of parameters derived from the dose-response curve such as the LD50 and TD50 may be... 

Drug Dose 67 Routes of Administration Drug Absorption 72 Drug Distribution 74 Drug Elimination 75 Pharmacodynamics 80 The Dose-Effect Curve Effective and Lethal Doses Drug Interactions 86 Summary 89... 

The Dose-Effect Curve Effective and Lethal Doses Drug Interactions Summary... 

E. Quantal Dose-Response Relationships When the minimum dose required to produce a specified response is determined in each member of a population, the quantal dose-response relationship is defined (Figure 2-2). When plotted as the fraction of the population that responds at each dose versus the log of the dose administered, a cumulative quantal dose-response curve, usually sigmoid in shape, is obtained. The median effective (ED j,), median toxic (TD, ), and median lethal doses (LD j,) are extracted from experiments carried out in this manner. 

The lethal dose is only one characteristic of the different toxic effects. The toxic effect starts, however, at clearly smaller doses in the body and follows a substance-specific dose-response curve. All substances show more or less similar behavior in the case of low doses with decreasing amounts of the substance smaller effects are observed, and finally, with a substance-specific dose, no effects occur. For all substances, except in the case of some special properties like genotoxic effects, the shapes of the dose-response curves are similar. 

Maximum air pollution concentrations —> Dose-response relationship/curve Median effective dose (ED J Dose-response relationship/curve Median lethal dose (LD g) Dose-response relationshipcurve Median lethal concentration (LCj ) Dose-response relationship/curve... 

Effective dose (ED) The dosage at which the effects of a toxic material are noticeable but minor and reversible. The specific values are often plotted as dose-response curves or given as EDio or EDso- The latter is the effective dose at which symptoms are noticeable in 50% of flie reported subjects. The values of the ED are always less than tire toxic dose (TD). See lethal dose and toxic dose. 

Toxic dose The dosage at which the effects of a material are noticeable and irreversible. Data are often plotted on response vs. dosage curves or listed as, for example, TDio or TD50. TD50 is the dose at which symptoms are toxic for 50% of the reported subjects. Also see effective dose and lethal dose. 

The answer s3 IIFI b (6)J. The slope of the LD50 curve shows the range between no effect and maximal effect (I-D,qq) and is thus a measure of the probability of surviving a lethal dose (l.e., a lethal dose is likely to kill most of a population exposed). For example, a compound with a steep curve would make an effective rodenticide because the lethal dose range is narrow and survivors are unlikely. 

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