Lethal Dose


A Lethal dose is a quantity of a medicine or other substance that, if administered, will kill a human or animal.

Lethal Doses/concentrations:

Lethal Dose 0% (LD0): The Lethal Dose 0 percent (LD0) is the lowest dose at which no one is predicted to die. This is just on the verge of being fatal.

Lethal Dose 10% (LD10): The Lethal Dose 10 percent (LD10) refers to the dose at which 10% of the people will die.

Lethal Concentration 50% (LC50): For inhalation toxicity, air concentrations are utilised to calculate exposure values. The LC50 is the determined concentration of a gas that is deadly to 50% of a population.

The amount of an ingested drug that kills 50% of a test sample is known as the lethal dose (LD50). It’s measured in milligrammes of material per kilogramme of body weight, or mg/kg.

Toxicity measures

A common dose estimate for acute toxicity is the LD50 (Lethal Dose 50%). It’s a statistically calculated maximum dose at which half of a group of organisms (rats, mice, or other species) should die. Because of the ethics of using huge numbers of animals, the heterogeneity of reactions in animals and people, and the use of mortality as the only endpoint, LD50 testing is no longer the preferred approach for determining toxicity. Regulatory authorities only utilise LD50 if scientific necessity and ethical concerns justify it

Toxicity Measures commonly used are:

NTEL: No Toxic Effect Level (NTEL), is the highest dose administered to the most sensitive species in a toxicology research for a particular duration that produced no toxic effect.
In most cases, the predicted NTEL in the most sensitive species is utilised to set the starting dose in the first human trials. The safety factor used may range from 100 to 1000, depending on the available knowledge, the type and severity of toxicities reported in animals, and if these projected toxicities can be monitored in humans using non-invasive approaches.

NOAEL: The No Observed Adverse Effect Level (NOAEL) is the largest dose that does not cause tissue toxicity or unpleasant physiological effects such as drowsiness, seizures, or weight loss.

MTD: Maximum Tolerated Dose (MTD), which is typically employed in long-term research and reflects the highest dose tested that resulted in no visible indicators of ill-health.

NOEL: The threshold for producing any recognised pharmacological or hazardous effect is known as the No Observed Effect Level (NOEL).

The NOEL (no observable effect level) is the highest dose or exposure level of a substance or material that produces no noticeable (observable) toxic effect on tested animals.

LOAEL: The Lowest Observed Adverse Effect Level  (LOAEL) is the lowest dosage level at which chronic exposure to the substance shows adverse effects on tested animals.