185 / 795
3. 
3.1.3.10.4. Table - Opioid agonists Opioid agonists
|
Potency (IV, appr) |
Vd | PB |
Lipid solubility |
pKa | % non-ionised | HER | Clearance | T1/2 |
CSHT (4hr) |
Equ'n time | |
| Morphine | 1 | 3-5 L/kg | 35% | 1 | 7.9 | 23% | 0.6-0.8 | 15 - 30 mL/kg/min | 1.7 - 3.3 hr | ||
| Pethidine | 0.1 | 3-5 L/kg | 70% | 32 | 8.5 | 7% | 0.5-0.7 | 8 - 18 mL/kg/min | 3 - 5 hr | ||
| Fentanyl | 100 | 3-5 L/kg | 84% | 955 | 8.4 | 8.5% | 0.8-1.0 | 10 - 20 mL/kg/min | 3.1 - 6.6 hr | 260 min | 6.8 min |
| Sufentanil | 1000 | 2.5-3 L/kg | 93% | 1727 | 8.0 | 20% | 0.7-0.9 | 10 - 15 mL/kg/min | 2.2 - 4.6 hr | 30 min | 6.2 min |
| Alfentanil | 10 | 0.4-1.0 L/kg | 92% | 129 | 6.5 | 89% | 0.3-0.5 | 4 - 9 mL/kg/min | 1.4 - 1.5 hr | 60 min | 1.4 min |
| Remifentanil | 2000 | 0.2-0.3 L/kg | 80% | 7.3 | 58% | 30 - 40 mL/kg/min | 0.17 - 0.33 hr | 4 min | 1.1 min | ||
| Others | |||||||||||
| Tramadol | 2 - 3 L/kg | 20% | 9.41 | 6 - 9 mL/kg/min | 5 - 7 hr
6 - 8 hr (M1) |
||||||
| Paracetamol (IV) | 1 - 1.2 L/kg | Low | 1 - 3 hrs | 45 min | |||||||
| Aspirin | 9.41 | 6 - 9 mL/kg/min |
15 - 20 min 2 - 3 hrs (salicylate) |
| Onset | Peak | Duration | |
| Morphine | 15 - 30 min | 45 - 90 min | 4 hours |
| Pethidine | 2 - 4 hours | ||
| Fentanyl | 2 - 5 min | 30 - 60 min | |
| Sufentanil | 1 - 6 min | 0.5 - 8 hours | |
| Alfentanil | 10 - 20 min | ||
| Tramadol | |||
| Paracetamol (IV) | 5 - 10 min | 4 - 6 hrs | |
| Aspirin |
NB:
- Potency table is a very rough estimation
* Fentanyl is 75-125 times as potent as morphine
* Sufentanil is about 10 times as potent as fentanyl
* Alfentanil is about 1/10 as potent as fentanyl
* Remifentanil is 15-20 times as potent as fentanyl - Fentanyl
* > 80% leaves plasma in less than 5 min after initial dose