Hexobarbital or hexobarbitone, (sold both in acid and sodium salt, brand name Evipan, and Tobinal), is a barbiturate derivative having hypnotic and sedative effects. It was used in the 1940s and 1950s as an agent for inducing anesthesia for surgery, as well as a rapid-acting, short-lasting hypnotic for general use, and has a relatively fast onset of effects and short duration of action. It was also used to murder women prisoners at Ravensbruck Concentration Camp. Modern barbiturates (such as Thiopental) has largely supplanted the use of hexobarbital as an anesthetic, as they allow for better control of the depth of anesthesia. Hexobarbital is still used in some scientific research. Hexobarbital binds at a distinct binding site associated with a Cl- ionophore at the GABA-A receptor, increasing the duration of time for which the Cl- ionophore is open. The post-synaptic inhibitory effect of GABA in the thalamus is, therefore, prolonged.

Tricaine (MS-222, Tricaine-S), a water-soluble local anesthetic, is used commonly for sedation, immobilization, and anesthesia of poikilothermic animals and has been accepted as a common anesthetic for use in the cold-blooded animals. It has long been recognized as a valuable tool for the proper handling of these animals during manual spawning (fish stripping), weighing, measuring, marking, surgical operations, transport, photography, and research. Tricaine was developed by Merck as a sulfonated analog of benzocaine with high solubility in water. The main advantage of Tricaine is the short duration of action and rapid metabolism. There are many reports describing the use of Tricaine for anesthetizing poikilothermic animals because it is a safe agent for immersion anesthesia even though the other anesthetics such as ether, ethanol, thiopental, halothane, isoflurane, barbiturates also could be used. Amphibians could be anesthetized easily by immersion methods with Tricaine because the amphibian skin is extremely permeable and water is absorbed through the skin rather than ingested. Tricaine has been administered as an injectable agent also.

Clove oil is a natural product, derived from the Eugenia caryophyllata tree. Clove oil is 85 to 95% eugenol. Isoeugenol and methyleugenol make up 5 to 15% of the remaining ingredients. Isoeugenol is manufactured from eugenol by a process of isomerization. Isoeugenol have been used in foods and eugenol has been used in animal feeds. Isoeugenol is used as a fish anesthetic. The mechanism of action of isoeugenol in fish has not been determined. It is hypothesised that its effects are mediated via receptors controlling cellular ion channels in a similar way to that described for local anaesthetics. Reports of adverse reactions involving the use of isoeugenol in humans are primarily confined to incidents of contact sensitization or allergy following dermal exposure.