Choosing an opioid
Objective 3: Understand the pharmacology relevant to choosing an opioid for pain treatment in terminally ill patients.
A. Be familiar with the WHO ladder approach to pain management.
B. Mild opioids: codeine, hydrocodone, oxycodone.
C. Major opioids: morphine, meperidine, hydromorphone, fentanyl, methadone.
D. Be familiar with equianalgesia tables ( you do NOT need to commit these to memory!!).
A. The WHO ladder approach (stepped care) to pain management.
The World Health Organization (WHO) recommends a simple and effective three-step process, or ladder (Figure 1), for titrating pharmacologic therapy that provides effective pain relief for more than 90% of terminally ill patients.
Step One: The first step of the ladder is to use acetaminophen, aspirin, or other NSAIDs to relieve mild to moderate pain.
Step Two: When pain persists or increases, the second step is to add a mild opioid, such as codeine or hydrocodone to the NSAID. When the second step is initiated, medications for persistent pain are administered on an around-the-clock basis, with additional "as needed" booster doses to control break-through pain.
Step Three: The third step of the ladder is to replace the mild opioid with a more potent opioid such as morphine or hydromorphone. The third step is initiated when, despite treatment with the mild opioid, pain persists or increases.
B. Mild opioids: All are full mu agonists with relatively low analgesic efficacy. All are generally administered as fixed-dose combination products with aspirin or acetaminophen. When using these products, the toxicity of the non-opioid limits the dose of the opioid that can be administered daily.
C. Major opioids: All are full mu agonists with high analgesic efficacy
1. Morphine: considered the "gold standard" for pain relief in terminally ill patients because
2. Meperidine (Demerol): this is a poor choice for chronic pain therapy because:
Learn more about "The Use and Misuse of Demerol"
D. Equianalgesia tables
Equianalgesia tables are used when switching from one opioid to another, or when switching routes of administration. This helps physicians to minimize problems related to underdosing or overdosing. Remember, "equianalgesia" simply refers to how much of drug A is needed to provide the same pain relief as x amount of drug B. However, comparative values are approximate - no really solid scientific studies are available for most. In reality, you must clinically titrate. The only one who can really define the equianalgesic (or adequately analgesic) dose is the patient.
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