| Class | Opioid |
|---|---|
| Chemistry |
Synthetic piperidine opioid |
| Routes of administration |
IV |
| Absorption |
Well absorbed orally, 50% oral bioavailability |
| Solubility |
pKa 6.5, 90% unionised at pH 7.4; octanol-water partition coefficient ~ 128 |
| Distribution |
VOD = 0.4-1.0L/kg; 88-92% protein-bound |
| Metabolism |
Hepatic metabolism; notable metabolites include inactive metabolites |
| Elimination |
Minimal unchanged drug cleared renally, but most of the metabolites rely on renal excretion |
| Time course of action |
Half-life si 2 hrs |
| 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 3 |
| Mentioned around Deranged Physiology | |
| Related SAQs |