Nitenpyram is a chemical frequently used as an insecticide in agriculture and veterinary medicine. The compound is an insect neurotoxin belonging to the class of neonicotinoids which works by blocking neural signaling of the central nervous system. It does so by binding irreversibly to the nicotinic acetylcholine receptor (nACHr) causing a stop of the flow of ions in the postsynaptic membrane of neurons leading to paralysis and death. Nitenpyram is highly selective towards the variation of the nACHr which insects possess, and has seen extensive use in targeted, insecticide applications.

Known under the codename TI 304 during field testing starting in 1989, the compound's first documented commercial use was in 1995 under the name "Bestguard" as an agricultural insecticide. Later, nitenpyram was expanded for use as a flea treatment by the Novartis company under the trade name "Capstar", with a subsequent FDA approval for non-food producing animals in October 2000. The current producer of nitenpyram itself is the Sumitomo chemical company. Nitenpyram continues to be used commercially, though data from market surveys indicate a significant decrease in the global usage compared to other insecticides or neonicotinoids.

Due to its use as an insecticide and treatment of non-food producing animals, it was not deemed necessary to research the human toxicology during its main use, and, as such, not much is known about the details of nitenpyram's effects on humans. Looking at rat experiments however, the lethal amount of nitenpyram is quite high (on the order of grams) in mammals in general, whereas invertebrates will die with only micro or nanograms of the substance.

Neonicotinoids, in general, have a low degradation rate when used for agricultural purposes, which allows for long-lasting protection of the crops against plant-sucking insects and indirectly the plant diseases these insects might carry.

Nitenpyram ( (E)-N-(6-Chloro-3-pyridylmethyl)- N-ethyl-N'-methyl-2-nitrovinylidenediamine) is an open-chain chloropyridyl neonicotinoid. Nitenpyram consists of a chloronicotinyl heterocyclic group common to all first generation neonicotinoids and a pharmacophore, the reactive group of the molecule. Nitenpyram possesses a nitroamine pharmacophore which is known to be the main reaction site in the binding of the compound to the nACh receptor, though the specificity of the reaction is not yet fully understood for neonicotinoids in general. Due to its polar groups, nitenpyram is quite hydrophilic, with an extremely high water solubility.

Though neonicotinoids are the largest group of insecticides used in today's agricultural world and prevalent in veterinary treatments, toxicity in general, e.g., genotoxicity and biotransformation, remains among the most controversial matters on the topic of neonicotinoids. This is primarily due to the lack of concrete systematic work. However, studies have been done on binding phenomena between neonicotinoids and proteins, serving as an indicator to its likely behavior in human physiological conditions.

Nitenpyram, a synthetic, nicotine-related chemical (neonicotinoid), has an effect on the nicotinic acetylcholine receptors and, for this reason, is considered similar to nicotine (agonists). Nicotinic acetylcholine receptors are involved in the sympathetic and parasympathetic nervous systems, present on the muscle cells where the cells from the nervous systems and the muscle cells form synapses. Variations in nicotinic-acetylcholine-receptor-binding affinity persists between species.

Although nitenpyram is an agonist of nicotine for the nicotinic acetylcholine receptor, it has a much lower affinity for the nicotine acetylcholine receptor in mammals. For most insects nitenpyram is a very lethal compound. Nitenpyram will bind irreversibly to the nicotinic acetylcholine receptors, paralysing those exposed to the compound. Despite lower affinity levels, mammals can still get a nicotine poisoning response from too much neonicotinoids, hence it is of importance to provide the appropriate dose for a flea-infested pet and it's always best to consult a vet.