RWJ-394674 is a drug that is used in scientific research. It is a potent, orally active

analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...

drug that produces little

respiratory depression Hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate (''hypo'' meaning "below") to perform needed respiratory gas exchange. By definition it causes an increased concentration of carbon dioxide (hypercapnia ...

. RWJ-394674 itself is a potent and selective

agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...

for δ-opioid receptors, with a Ki of 0.24 nM at δ and 72 nM at μ. However once inside the body, RWJ-394674 is dealkylated to its monodesethyl metabolite RWJ-413216, which is a potent agonist at the

μ-opioid receptor The μ-opioid receptors (MOR) are a class of opioid receptors with a high affinity for enkephalins and beta-endorphin, but a low affinity for dynorphins. They are also referred to as μ(''mu'')-opioid peptide (MOP) receptors. The prototypical � ...

and has less affinity for δ (Ki 0.26 nM at μ, 46.7 nM at δ). The effect of RWJ-394674 when administered ''in vivo'' thus produces potent agonist effects at both μ and δ receptors through the combined actions of the parent drug and its active metabolite, with the δ-agonist effects counteracting the respiratory depression from the μ-opioid effects, and the only prominent side-effect being

sedation Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure. Examples of drugs which can be used for sedation include isoflurane, diethyl ether, ...

References

Opioids Delta-opioid receptor agonists Tropanes Benzamides Mu-opioid receptor agonists {{analgesic-stub