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Dosing Analgesic Agents
Equivalent Doses of Narcotic Analgesics
(NEJM 1985, 313:84-95) |
| Drug | Equianalgesic Dose (mg) |
| IM | PO |
| Codeine | 130 | 200 |
| Hydromorphone (Dilaudid) | 1.5 | 7.5 |
| Levorphanol (Levo-Dromoran) | 2 | 4 |
| Meperidine (Demerol) | 75 | -- |
| Methadone | 10 | 20 |
| Morphine | 10 | 60 |
| Oxycodone (--) | 15 | 30 |
| Oxymorphone (Numorphan) | 1 | 10 (PR) |
Equivalent doses of Fentanyl Patch (Duragesic)
(Patch must be replaced q72 hrs)
(TDD= total daily dose)
Duragesic Product Information Insert. Janssen Pharmaceutica. 1991
|
TDD (mg/day)
of oral morphine | TDD (mg/day)
of IM morphine
| Fentanyl Patch
(µg/hr) |
| 45-134 | 8-22 | 25 |
| 135-224 | 28-37 | 50 |
| 225-314 | 38-52 | 75 |
| 315-404 | 53-67 | 100 |
| 405-494 | 68-82 | 125 |
| 495-584 | 83-97 | 150 |
| 585-674 | 98-112 | 175 |
| 675-764 | 113-127 | 200 |
| 765-854 | 128-142 | 225 |
| 855-944 | 143-157 | 250 |
| 945-1034 | 158-172 | 275 |
| 1035-1124 | 173-187 | 300 |
|
Dosing of Fentanyl Transmucosal Lozenges (Oralets) |
| Pt's age or wt | 5 - 10 µg/kg/dose | 10 - 15 µg/kg/dose |
Children <2 yrs
or <15 kg | not recom | not recom |
| <15 kg | n/a | 200 mg |
| 20 | 200 mg | 200-300 mg |
| 25 | 200 mg | 300 mg |
| 30 | 300 mg | 300-400 mg |
| 35 | 300 mg | 400 mg |
| >40 | 400 mg | 400 mg |
| Adults | 400 mg | 400 mg |
|
Comparative Pharmacokinetics |
| Drug | Onset
(min) | Peak
(min) |
t½
(hr) | Duration
(hr) | Dosing
Iinterval
(hr) | Equivalent
Dose (mg)* |
| IM | PO |
| Alfentanil | immed. | -- | -- | 1-2 | -- | -- | n/a |
| Buprenorphine | 15 | 1 | 4-8 | 2-3 | -- | n/a | n/a |
| Butorphanol | IM: 45
IV: 5 | 45 | 3-5 | 3 | 3-6 | 2 | -- |
| Codeine | PO: 45
IM: 20 | 45 | 4-6 | 3-4 | 3-6 | 120 | 200 |
| Fentanyl | IM: 10
IV: immed | n/a | 90 | 2-6 | 0.5-2 | 0.1 | n/a |
| Hydrocodone | n/a | n/a | 4-8 | 3-4 | 4-8 | n/a | n/a |
| Hydromorphone | PO: 15-30 | 45 | 4-6 | 2-4 | 3-6 | 1.5 | 7.5 |
| Levorphanol | PO: 10-60 | 45 | 4-8 | 12-16 | 6-24 | 2 | 4 |
| Meperidine | PO: 15
IM/SC: 10
IV: <5 | 45 | 2-4 | 3-4 | 2-4 | 75 | 300 |
| Methadone | PO: 45
IV: 15 | 45 | acute: 4-6
chrn: >8 | 15-30 | 8 | 10 | 20 |
| Morphine | PO: 15-60
IV: <5 | PO: 60
IM: 30
IV: 15 | 3-6 | 2-4 | 3-6 | 10 | acute:60
chrn:30 |
| Nalbuphine | IM: 30
IV: <3 | 60 | 3-6 | 5 | 3-6 | 10 | n/a |
| Naloxone | 3-5 | 30-120 | 0.5-1 | 0.5-1.5 | n/a | n/a | n/a |
| Oxycodone | PO: 10-15 | 45 | 4-6 | 3-4 | 3-6 | n/a | 30 |
| Oxymorphone | 5-10 | 45 | 3-6 | n/a | n/a | 1 | 10 (PR) |
| Pentazocine | 15-20 | 15-60 | 3-4 | 2-3 | 3-6 | n/a | n/a |
| Propoxyphene | PO: 45 | 120 | 4-6 | 3.5-15 | 4-8 | n/a | HCl: 130
naps: 200 |
| Sufentanil | 1-3 | n/a | n/a | 3 | n/a | 0.02 | n/a |
| * Based on acute short term use. Chronic administration may alter the pharmacokinetics leading to a marked decrease in the oral-to-parenteral dose ratio.
For morphine this ratio may decrease from 6 to 2.5 |
|
Comparative Pharmacology |
| Drug | Analgesic | Antitussive | Constipation | Resp Depr | Sedation | Emesis |
| Alfentanil | ++ | n/a | n/a | n/a | n/a | n/a |
| Codeine | + | +++ | + | + | + | + |
| Fentanyl | ++ | n/a | n/a | + | n/a | + |
| Hydrocodone | + | +++ | n/a | + | n/a | n/a |
| Hydromorphone | ++ | +++ | + | ++ | + | + |
| Meperidine | ++ | + | + | ++ | + | n/a |
| Methadone | ++ | ++ | ++ | ++ | + | + |
| Morphine | ++ | +++ | ++ | ++ | ++ | ++ |
| Nalbuphine | ++ | n/a | +++ | +++ | ++ | ++ |
| Oxycodone | ++ | +++ | ++ | ++ | ++ | ++ |
| Oxymorphone | ++ | + | ++ | +++ | n/a | +++ |
| Pentazocine | ++ | n/a | + | ++ | ++
or stimul | ++ |
| Propoxyphene | + | n/a | n/a | + | + | + |
| Sufentanil | +++ | n/a | n/a | n/a | n/a | n/a |
| Basic Definitons |
| Analgesia | Loss of pain sensation without loss of conciousness. |
| Somatic pain |
Pain originating in skeletomuscular structures, i.e., bone, skeletal muscles, and includes toothache, headache, and arthritic pain. |
| Visceral pain |
Pain originating in non-skeletal (i.e., visceral) structures, and includes gastric pain, intestinal cramps, etc. Visceral pain is relieved only by opioid analgesics. |
| Opiate |
A natural or synthetic substance that relieves pain by acting on the opioid receptors (see below). Most opiate drugs are structurally related to morphine. However, endorphins enkephalins and dynorphins are naturally occurring brain peptides that possess morphine-like actions. |
| Opioid agonists |
Natural or synthetic substances that bind specifically to opioid receptors and possess opioid or morphine-like properties. |
| Opioid antagonists |
Substances that bind to opioid receptors and block or reverse the effects of opioid agonists. |
|
Endogenous opioids |
Three groups of endogenous opioid peptides: endorphins, enkephalins and dynorphins. |
| Opioid Receptors |
The principal opioid receptors are: mu, delta and kappa. |
| Opioid Agonists and Antagonists |
| Agonists | Antagonists | Agonists-Antagonists |
| Severe Pain | Mild to Moderate Pain | Special Uses | | |
Morphine
Meperidine
Methadone
Fentanyl
Hydromorphone (Dilaudid)
Heroin |
Hydrocodone
Oxycodone
Propoxyphene | Diphenoxylate
Loperamide |
Naloxone (Narcan)
Naltrexone | Pentazocine
Nalbuphine |
| Acute Effects of Opioids |
| Chronic use of morphine and other opioids results in tolerance and dependence. Note that tolerance is not developed for miosis and constipation. Physical dependence is more likely to develop in association with the use of the more potent opioids. Upon discontinuation of the opioid, physical dependence may be observed as a withdrawal syndrome (chills, anxiety, hostility, myalgia, and diarrhea). |
| Analgesia | Mediated mainly by the µ (mu) receptors which suppress the peripheral nociceptive pathway and the pain processing cortex. |
| Respiratory Depression | Mediated by the µ receptors. Opioids reduce the sensitivity of the central chemoreceptors to CO2. This is the cause of death in cases of opioid overdose. |
| Sedation and Euphoria | are the result of subanalgesic stimulation of the µ receptors. |
| Antitussive Effect | are due to the depression of the medullary cough center. This occurs even with subtherapeutic doses of the opiod. Codeine and dextramethorphan are the opioids of choice for this effect. |
| Constipation | Mediated by reduced intestnal motility. |
| Miosis | one of the telltale signs of opioid exposure. |
| Emetic Effct | Opioids initially stimulate the chemoreceptor trigger zone (CTZ), causing nausea. However, chronic opioid use suppresses the medullary emetic center, resulting in an anti-emetic effect. |
| Smooth Muscle Effect | Opioids increase circular smooth muscle tone in biliary ducts, ureters, and bronchi, causing spasms in these structures. |
| Cardiovascular Effects | Peripheral vasodilation and postural hypotension may accompany the intravenous administration of relatively large doses of morphine |
| Histamine Release | results in urticaria, vasodilation, and bronchoconstriction. |
| Convulsant Effect | is observed in a small fraction of patients. Metabolites of meperidine and codeine have the tendency to trigger seizures, and should be used with extreme caution in patients with impaired renal function. |
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