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In toxicology, the median lethal dose, LD 50 (abbreviation for "lethal dose, 50%"), LC 50 (lethal concentration, 50%) or LCt 50 is a toxic unit that measures the lethal dose of a given substance. [1] The value of LD 50 for a substance is the dose required to kill half the members of a tested population after a specified test duration.
The median lethal dose, LD 50 (abbreviation for "lethal dose, 50%"), LC 50 (lethal concentration, 50%) or LCt 50 (lethal concentration and time) of a toxin, radiation, or pathogen is the dose required to kill half the members of a tested population after a specified test duration.
In contrast, in a drug development setting TI is calculated based on plasma exposure levels. [2] In the early days of pharmaceutical toxicology, TI was frequently determined in animals as lethal dose of a drug for 50% of the population (LD 50) divided by the minimum effective dose for 50% of the population (ED 50). In modern settings, more ...
This depends on the need for the effect, and also the toxicity. The toxicity and even the lethality of a drug can be quantified by the TD 50 and LD 50 respectively. Ideally, the effective dose would be substantially less than either the toxic or lethal dose for a drug to be therapeutically relevant.
TTX is extremely toxic. The material safety data sheet for TTX lists the oral median lethal dose (LD 50) for mice as 334 μg per kg. [47] For comparison, the oral LD 50 of potassium cyanide for mice is 8,500 μg per kg, [48] demonstrating that even orally, TTX is more poisonous than cyanide. TTX is even more dangerous if administered ...
The median lethal dose of a substance is defined as the dose that leads to death in 50% of the tested population. It is a significant parameter in toxicology study and indicates the acute toxicity of a particular substance. LD50 is usually expressed in the weight of the chemical administered in milligram per unit of body weight (mg/kg). [29]
It is calculated using the LD50 or LC50. [1] The Occupational Safety and Health Administration (OSHA) regulation (1910.134(b)) defines the term as "an atmosphere that poses an immediate threat to life, would cause irreversible adverse health effects, or would impair an individual's ability to escape from a dangerous atmosphere."
The more potent a particular substance is, the steeper this curve will be. In quantitative situations, the Y-axis often is designated by percentages, which refer to the percentage of exposed individuals registering a standard response (which may be death, as in LD 50). Such a curve is referred to as a quantal dose–response curve ...