Nicocodine is an opioid related to codeine. It is also an antitussive agent. Nicocodine exhibits at least twice the potency of codeine in clinical experiments. The study of the pharmacokinetic behaviour of nicocodine by means of blood and brain level curves of rats after i .v. application showed that the penetration of the blood brain barrier seems to be favoured for nicocodine. The detected peak concentration of nicocodine in brain after i.v. application is 4.4 times higher than the blood level values at the same time - codeine the main metabolite is detected in almost equal amounts in brain and blood. A comparative assay of codeine and nicocodine after p.o. application of equimolar doses per kg body weight revealed that predominantly codeine is found in brain and its peak value after nicocodine administration is 3-fold higher than after codeine administration. Nicocodine is hydrolysable to morphine and the WHO Expert Committee on Addiction-Producing Drugs (1962) recommended its international control as a narcotic, like other convertible drugs in the morphine series.

Norlevorphanol:
https://drugs.ncats.io/drug/DYX391P13E

Nicocodeine (Lyopect, Tusscodin) is an opiate derivative, closely related to dihydrocodeine and the codeine analogue of nicomorphine developed as a cough suppressant and analgesic. It is not commonly used in most countries, but has activity similar to other opiates. Nicocodeine and nicomorphine were introduced in the late 1950s by Lannacher Heilmittel of Austria. Nicocodeine is metabolised in the liver by demethylation to produce nicomorphine, also known as 6-nicotinoylmorphine, and subsequently further metabolised to morphine. Side effects are similar to those of other opiates and include itching, nausea and respiratory depression.

Nicocodeine:
https://www.chemeurope.com/en/encyclopedia/Nicocodeine.html

Nicocodeine cough medicines are available as syrups, extended-release syrups, and sublingual drops. Analgesic preparations are also in the form of sublingial drops and tablets for oral administration. Nicocodeine is approximately the same strength as hydrocodone; it has a faster onset of action. An opioid analgesic and cough suppressant, an ester of codeine. The codeine analogue of nicomorphine. It is not commonly used in most countries, but has activity similar to other opiates. Nicocodeine is almost always used as the hydrochloride salt. Nicocodeine is regulated in most cases as is codeine and similar weak opiate drugs. Nicocodeine was never introduced for medical use in the United States. The 2013 DEA annual production quota for nicocodeine and its two related drugs are zero.