What is the mechanism of action of an overdose of barbiturates for euthanasia?

The mechanism of action of an overdose of barbiturates primarily involves the depression of the central nervous system (CNS). When administered in excessive amounts, barbiturates enhance the activity of gamma-aminobutyric acid (GABA), a neurotransmitter that inhibits neuronal activity, leading to profound sedation and CNS depression. This results in respiratory depression, which can severely slow or completely halt breathing. As respiration ceases, oxygen supply diminishes, ultimately leading to cardiac arrest due to the lack of oxygenated blood reaching the heart muscle.

In the context of euthanasia, this mechanism is preferred as it results in a rapid and humane death, reflecting the ethical considerations involved in animal welfare. The understanding of how barbiturates act to depress neural activity including the respiratory centers is critical in ensuring that euthanasia is conducted in a manner that minimizes distress for the animal.