| Class | Opioid |
|---|---|
| Chemistry |
Semisynthetic phenanthrene |
| Routes of administration |
Oral, IV, topical |
| Absorption |
Well absorbed orally, 15% bioavailability due to high first pass effect |
| Solubility |
pKa 8..5, highly lipophilic |
| Distribution |
VOD = 87-197L/kg; 96% protein-bound |
| Metabolism |
Hepatic metabolism; notable metabolites include norbuprenorphine, an active metabolite |
| Elimination |
Minimal unchanged drug cleared renally, but most of the metabolites rely on renal excretion |
| Time course of action |
Half-life 35 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 |