| Class | Opioid |
|---|---|
| Chemistry |
Synthetic piperidine opioid
|
| Routes of administration |
Oral,...IV?... |
| Absorption |
Well absorbed orally, 80% oral bioavailability, but with a wide range of interindividual variation
|
| Solubility |
pKa 9.2, 1% unionised at pH 7.4, octanol-water partition coefficient ~ 117
|
| Distribution |
VOD = 1-8 L/kg; 85-90% protein-bound
|
| Metabolism |
Hepatic metabolism; notable metabolites include inactive metabolite EDDP
|
| Elimination |
At high doses (>55mg/day), renal clearance becomes an important route of elimination
|
| Time course of action |
Half life 20-60 hours
|
| Target receptor |
mu-opiate receptor (pre-synaptic G-protein coupled receptor) |
| Mechanism of action |
Hyperpolarisation of cell membrane by increasing potassium conductance; reduced production of cAMP and closure of voltage-gated calcium channels |
| Clinical effects |
Analgesia, respiratory depression, constipation, miosis, urinary retention. |
| Literature reference |
Crow et al (2021) |
| CICM details of understanding | Level 2 |
| Mentioned around Deranged Physiology | |
| Related SAQs |