In toxicology, the lethal dose (LD) is an indication of the lethal toxicity of a given substance or type of radiation. Because resistance varies from one individual to another, the "lethal dose" represents a dose (usually recorded as dose per kilogram of subject body weight) at which a given percentage of subjects will die. The lethal concentration is a lethal dose measurement used for gases or particulates. The LD may be based on the standard person concept, a theoretical individual that has perfectly "normal" characteristics, and thus not apply to all sub-populations.

Median lethal dose

The median lethal dose, LD50, LC50 (lethal concentration, 50%) or LCt50 (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. LD50 figures are frequently used as a general indicator of a substance's acute toxicity. A lower LD50 is indicative of increased toxicity.

The test was created by J.W. Trevan in 1927. The term "semilethal dose" is occasionally used with the same meaning, in particular in translations from non-English-language texts, but can also refer to a sublethal dose; because of this ambiguity, it is usually avoided. LD50 is usually determined by tests on animals such as laboratory mice. In 2011 the US Food and Drug Administration approved alternative methods to LD50 for testing the cosmetic drug Botox without animal tests.

Measures commonly used are: no toxic effect level (NTEL), which is the largest dose in the most sensitive species in a toxicology study of a given duration which produced no observed toxic effect, no observed adverse effect level (NOAEL), which is the largest dose causing neither observed tissue toxicity nor undesirable physiological effects, such as sedation, seizures or weight loss, maximum tolerated dose (MTD), which usually applies to long-term studies and represents the largest dose tested that caused no obvious signs of ill-health and no observed effect level (NOEL), which represents the threshold for producing any observed pharmacological or toxic effect.

The Journal of “Clinical Pharmacology and Toxicology Research” is using Editorial Tracking System to maintain quality and transparency to the author in the peer-review process. Review processing will be performed by the editorial board members of the Journal of “Clinical Pharmacology and Toxicology Research” or by Reviewers (outside experts in the field). Two independent reviewer’s approval (Minimum reviewer’s approval) followed by editor approval is obligatory for acceptance of any manuscript excluding an editorial.

Regards

Mary Wilson

Editorial office

Clinical Pharmacology and Toxicology Research

E-mail: pharmatoxicol@eclinicalsci.com