TABLE 12.
Use of opioids in chronic pain management
| Dose equivalent to morphine 10 mg IM | ||||||
|---|---|---|---|---|---|---|
| Drug | Common trade name | IM | PO | IM:PO potency ratio | Elimination half-life (h) | Duration of action (h) |
|
Agonists | ||||||
| Morphine | Morphine | 10 | 20–30 | 1:3 | 2–3.5 | 3–4 |
| Oxycodone | Percocet (with acetaminophen)* | |||||
| Percodan (with acetylsalicylic acid)* | – | 10–15† | 1:15 | 2–4 | 3–6 | |
| Supeudol (Sabex Inc, Canada) | ||||||
| Hydromorphone | Dilaudid (Abbott Laboratories, Canada) | 2 | 4–6‡ | 1:5 | 2–3 | 2–4 |
| Fentanyl (transdermal) | Duragesic (transdermal) (Janssen-Ortho Inc, Canada) | 0.1§ | – | 1–2 | 72 per patch | |
| Methadone | Methadone hydrochloride powder Metadol (Pharmascience, Canada) | 1.7–5¶ | 1:2 | 15–190 | 4–24 | |
| Codeine | Codeine | 120 | 200 | 2–3 | 4–6 | |
| Tramadol | Tramacet (Janssen-Ortho Inc, Canada) (with acetaminophen) | 200** | 1:1.2 | 3–4 | 4–6 | |
| Meperidine†† | Demerol (Sanofi-Synthelabo Inc, Canada) | 75 | 300 | 1:4 | 2–3 | 2–4 |
|
Mixed agonists/antagonists | ||||||
| Pentazocine†† | Talwin (Sanofi-Synthelabo Inc, Canada) | 60 | 180 | 1:3 | 2–3 | 3–4 |
| Butorphanol | Transnasal butorphanol | 2 | 2.5–3.5 | 3–4 | ||
Endopharmaceuticals Inc, USA;
Oxycodone is approximately twice the potency of morphine;
Hydromorphone is approximately five times the potency of morphine;
Empirically: transdermal fentanyl 100 μg/h = intramuscular (IM) Morphine 2–4 mg/h (available in patches to deliver 25, 50, 75, 100 μg/h, detailed conversion are available in the Compendium of Pharmaceuticals and Specialties, 2005);
The equipotent methadone dose varies and depends on the previous dose of opioid and individual pharmacokinetics. Methadone ranges from four to 12 or more times the potency of morphine, the relative potency of methadone is higher with higher doses of the previous conventional opioid. Care should be taken in opioid rotation especially if the patient is on high doses of a conventional opioid, lower relative doses of methadone will be required, for detailed conversion ratios see [178];
Difficult to define equipotent dose because tramadol is only available in Canada in combination with acetaminophen. Tramadol has weak opioid agonist effects in a range similar to codeine, Tramacet tablets contain 37.5 mg of tramadol and 325 mg of acetaminophen, tramadol also exhibits monoaminergic effects, it is important to be aware of this in patients using antidepressants or other agents with monoaminergic action;
Meperidine and pentazocine are not appropriate for chronic use.
Transnasal relative potency and duration of action equivalent to parenteral morphine