| Structure/Class |
|
| Pharmacodynamics |
- Methadone is active at several receptors.
- It is a potent µ receptor agonist
- It blocks the NMDA receptor and blocks monoaminergic re-uptake.
- As such, it has several useful indications:
- Difficult to treat pain (E.g. cancer, neuropathic). Used based on the concept of opioid rotation.
- Useful in detoxification of addictions – this is due to its good oral bioavailability and long T ½. It produces milder (but more prolonged) withdrawal signs and symptoms.
|
| Absorption/administration |
- PO, can also be given IV, SC, intrathecal and rectal.
|
| Distribution |
- Well absorbed from the GIT, and has high bioavailability.
|
| Metabolism |
- Hepatic – via CYP 3A4 and CYP 2D6 pathways.
- It has a long T ½ – 25 to 50 hours. It is excreted in the urine and does not have any active metabolites.
|
| Excretion |
- Renal
|
| Indications |
|
| Contraindications |
|
| Special precautions |
|
| Interactions |
|
| Adverse events |
- Hepatic impairment may lead to accumulation and prolonged QT.
|
| Dosing/administration |
|
| Toxicology |
|
| Withdrawal syndrome |
|
| Special notes |
|
