Dextromoramide is a synthetic strong-acting opioid and full mu-opioid receptor agonist. Dextromoramide is a Schedule I drug illegal to possess. The current indication for Palfium (dextromoramide) is severe acute or chronic pain requiring opioids, such as post-operative pain, and pain associated with bone fractures, malignancies and acute renal/biliary colic attacks in adults.

Dextromoramide:
https://drugs.ncats.io/drug/9S4S6CIY83

Palfium (dextromoramide) is a powerful opioid analgesic approximately three times more potent than morphine but shorter acting. It is also claimed to be three times more euphoric than heroin in equal doses. It has a high bioavailability, making oral administration nearly as effective as injection. The only place it is still marketed is the Netherlands.

• You know the dose is completely unpredictable right? This is why it was taken off the market. Your first dose could be 10mg and feel very little but the next dose at 2mg could kill you. It's a very dangerous drug.
• Some things that stood out to me are: relatively lower withdrawal symptoms compared to Morphine, tolerance builds slower than Morphine, orally active compared to IV, less constipation, fast onset and it seems like a very euphoric drug by weight.

A Reddit Discussion:
https://www.reddit.com/r/ObscureDrugs/comments/393z6n/king_of_opiates_part_ii_palfium/

Dextromoramide

Duration: a rare and powerful opioid analgesic approximately three times as potent as morphine with a shorter duration. Generally only seen in the Netherlands. Reported as having strange and rapid tolerance behaviour.
Route	Onset	Duration	After Effects
Tripsit Factsheets
Dextromoramide Basic Information: http://drugs.tripsit.me/palfium
Intravenously:	1-2 minutes	2-3 hours	1-12 hours
Oral:	5-15 minutes	3-5 hours	1-12 hours
Avoid: All other CNS depressants.

Palfium study from 1995
The palfium 'high' is not experienced by everybody, particularly during the first weeks of use. If an intoxicating effect does occur, this is described as a warm, comfortable feeling, which is less intense than a heroin 'high'. The so-called 'rush' which takes place during the intravenous use of heroin does not happen. With a few exceptions, those who smoke heroin also say they experience a lesser effect from palfium.

The intoxication differs from a heroin 'high' in that palfium contains a stimulant. In particular, the narcotic, dazing effect of heroin is lesser with palfium: "With palfium you don't get stoned, you talk more more and you can do things." The stronger painkilling effect of palfium is also cited as a difference. Two clients with back problems and one person with AIDS and unexplained pain saw this difference as a positive aspect of palfium. Most clients, however, prefer heroin to palfium: "Nothing is like heroin, nothing." Only one person said they preferred palfium, the reason being its stimulating effect: "I find it better than heroin because you don't get completely stoned, and I'm too proud for that."

By comparison with those of heroin, the duration of the effects produced by palfium are shorter to much shorter. It acts rapidly following oral intake, with a light, warm 'glow' throughout the body. The treatment did not succeed with those clients for whom this effect was only very short-lasting. For most of the clients, however, the effects of palfium lasted one-and-a-half to two hours. During the treatment programme, palfium for the weekend was also distributed on Friday, which caused half the clients to have problems on Sundays due to overconsumption of the palfium on the previous Friday and Saturday. Some clients protected themselves against this risk by allowing (non-drug using) third parties (their partner or parents) to look after their palfium.

- http://www.druglibrary.org/schaffer/heroin/MANGOES.HTM#10.1%20Intoxicating%20effects

Dextromoramide:

Usually only prescribed in the Netherlands

• A powerful opioid analgesic
• Approximately three times more potent than morphine but shorter acting
• Discovered and patented in 1956 by Dr Paul Janssen at Janssen Pharmaceutica, who also discovered fentanyl
• The main advantage of this drug is that it has a fast onset of action when taken orally, and has a high bioavailability which means that oral dosing produces almost as much effect as injection.

Dextromoramide was singled out along with ketobemidone and several other synthetics by the United Nations and European Union as being "extra-dangerous" in the early 1960s, with dextromoramide being alleged to be three times more euphoric than heroin at equal doses, though this did little to stem production in the first half of the decade. Dextromoramide was much favoured by drug users in Australia in the 1970s and the United Kingdom.