Comment
Author: Admin | 2025-04-28
Potency related to 10 mg of intravenously administered morphine.DrugEquivalent doseRelative potencyHalf-lifeMorphine (IV)10 mg12-3 hoursMorphine (oral)30 mg1/32-4 hoursMorphine (SC)15 mg2/3n/aDiamorphine (SC) (heroin)10 mg12-3 minutesOxycodone (oral)15 mg2/33-4.5 hoursOxycodone (SC)10 mg13-4.5 hoursAlfentanyl (SC)1 mg101.5-2 hoursFentanyl (SC)0.200 mg50n/aHydromorphone (oral)4 mg2/52-3 hoursHydromorphone (SC)2 mg1/52-3 hoursCodeine (oral)300 mg1/302.5-3 hoursTramadol (oral)300 mg1/306-8.8 hoursFentanyl (transdermal)0.300 mg20-277 hoursBuprenorphine (transdermal)0.400 mg2520-70 hoursHow to calculate equivalent morphine dosage when changing the method of administrationThe dosage changes significantly with the chosen route of drug administration. Let's assume you're giving your patient 20 mg of morphine a day intravenously. According to the relative potencies in the equianalgesic chart, you'll see that:If the daily dose for intravenous route is 20 mg;The daily dose for oral administration is 60 mg; andThe daily dose for subcutaneous administration is 30 mg.Opiate conversion with an incomplete cross-tolerance adjustmentCross-tolerance is a phenomenon that occurs in many drug groups and has consequences in the usage of opiates. It is described in the article Opioid Tolerance Development: A Pharmacokinetic/ Pharmacodynamic Perspective:Long-term exposure to one drug often results in the development of tolerance to the effects of other structurally similar drugs in the same pharmacologic class.Surprisingly, cross-tolerance between opioids is often incomplete. In practice, it means that after opiate conversion, the dosage needs to be lowered, even by 25-50%. You can input this value in the incomplete cross-tolerance field in the opioid conversion calculator.
Add Comment