Conventional analgesic drugs
First order: non-opioid drugs, meaning NSAIDs such as acetaminophen, can enhance the effect of second and third order drugs, with capping effect;
Second tier: weak opioids, a combination of weak opioid NSAIDs and tramadol, etc., with a capping effect;
Third order: strong opioids, represented by morphine, with no capping effect; strong opioids with no dose limit: when the drug is not effective, the dose can be increased instead of adding another similar drug.
Dose conversion.
Morphine oral dose × 1/3 = morphine injection dose;
Oral morphine daily dose (mg/d) × 1/2 = Doregine (fentanyl patch) amount (ug/h)
Strong opioids
Selection of initial dose
Mild pain ( 1-3 )
Non-steroidal anti-inflammatory drugs alone
NSAIDs + opioid combination
Immediate release agents can be doubled at bedtime
Moderate pain ( 4-6 )
Morphine immediate release tablets 5-10mg PO q4h, 2.5-7.5mg PO q2h PRN
Opioid compound 1-2# PO q4h, 1/2-1# PO q2h PRN
Strong opioid analgesics (see severe pain)
Severe pain ( 7-10 )
Morphine immediate release tablets 10-30mg PO q4h , 5-15mg PO q2h PRN
Morphine extended-release tablets 30mg q12h, immediate release tablets 10mg q3-4h PRN
Fentanyl transdermal patch 25 mg patch q72h, immediate-release tablet 10mg q3-4h PRN
Oxycodone extended-release tablets 10 mg q12h, alternate morphine immediate-release tablets
Strong opioids
Dose adjustment required
Pain level Dose increase
≥7 points 50%-100%
5-6 points 25%-50%
≤4 points 25%
Example: pain score of 10 with OxyContin 10mg q12h, pain assessed at 8 after 24h, dose should be adjusted to 15-20mg q12h.
Note: Fentanyl patches are not indicated for patients with unstable pain control and initial use of strong opioids. After the daily dose of morphine has been mapped out, it can be converted to a patch depending on the condition or the patient’s wishes.
Doregis (fentanyl patch) dose.
Dose to be applied when switching patches = dose of previous patch + average daily dose of injectable morphine used in the previous 3 days x 3/2 (or average daily dose of oral immediate release morphine x 1/2)
Outbreak pain management
Oral immediate-release morphine = 1/3* single dose of controlled-release morphine
Morphine injection dose = 1/9 * single dose of controlled release morphine
Example: If you use Meclizine 30mg q12h for a long time, when you have an outbreak of pain: oral morphine 30×1/3=10mg, or subcutaneous morphine 10×1/3=3.3mg;
Another example is long-term use of OxyContin 20mg q12h, in case of outbreak pain: oxycodone dose*2=morphine dose, oral morphine=20*2*1/3=13.3mg, or subcutaneous morphine 20*2*1/3*1/3=4.4mg
Adjuvant medication
Dexamethasone: 5-20mg per dose, orally or intravenously, as appropriate;
Anticonvulsants: gabapentin, pregabalin. Start with small doses and keep adjusting the dose, gabapentin is generally used at a daily dose of 1800-3600mg;
Antidepressants: amitriptyline, etc., for pain relief generally do not need too large a dose, 12.5-25mg
Sedative-hypnotics: lorazepam, etc;
Criteria for pain to be controlled under treatment
NRS < 3 points, number of painful outbreaks < 3 in 24 hours, and the patient himself is satisfied with pain control.