Allylnorpethidine is a 4-phenylpiperidine

Piperidine

Piperidine is an organic compound with the molecular formula 5NH. This heterocyclic amine consists of a six-membered ring containing five methylene units and one nitrogen atom...

 derivative that is related to the opioid

Opioid

An opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract...

 analgesic

Analgesic

An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....

 drug pethidine

Pethidine

Pethidine or meperidine Pethidine (INN) or meperidine (USAN) Pethidine (INN) or meperidine (USAN) (commonly referred to as Demerol but also referred to as: isonipecaine; lidol; pethanol; piridosal; Algil; Alodan; Centralgin; Dispadol; Dolantin; Mialgin (in Indonesia); Petidin Dolargan (in Poland);...

 (meperidine).

Allylnorpethidine is an analogue of pethidine where the N-methyl group has been replaced by allyl

Allyl

An allyl group is a substituent with the structural formula H2C=CH-CH2R, where R is the connection to the rest of the molecule. It is made up of a methylene , attached to a vinyl group . The name is derived from the Latin word for garlic, Allium sativum. Theodor Wertheim isolated an allyl...

. In many other opioid derivatives, placing an allyl substituent on the nitrogen instead of a methyl will reverse the normal opioid effects, to produce μ-opioid

Mu Opioid receptor

The μ-opioid receptors are a class of opioid receptors with high affinity for enkephalins and beta-endorphin but low affinity for dynorphins. They are also referred to as μ opioid peptide receptors. The prototypical μ receptor agonist is the opium alkaloid morphine; μ refers to morphine...

 antagonists which among other things reverse the respiratory depression caused by opioid agonists such as morphine

Morphine

Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...

. This is not true with allylnorpethidine, as while it does partially reverse the respiratory depression produced by morphine it is actually an active analgesic and has no antagonistic properties when administered alone, so is instead a partial agonist

Partial agonist

Partial agonists bind and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist...

.