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Pharmacology of Opioids
Published in Pamela E. Macintyre, Stephan A. Schug, Acute Pain Management, 2021
Pamela E. Macintyre, Stephan A. Schug
The major desirable effect of opioids is analgesia, which is mediated mainly via the μ receptor, although δ and κ receptor effects can also contribute to pain relief. All full μ agonists are capable of producing the same degree of pain relief. Therefore, they can theoretically be made equianalgesic if adjustments are made for dose and route of administration (Table 4.2). However, it must be noted that standard equianalgesic dose tables often present average data based largely on single-dose studies of the drugs in a variety of clinical situations and patients. Interindividual differences in pharmacodynamics, pharmacokinetics, comorbidities, concurrent medications, age, and genetics, as well as incomplete cross-tolerance between opioids in patients on long-term opioid therapy are just some of the variables that can have a significant effect on the total daily doses that may be required. Care must be taken when one opioid is changed to another based on such tables alone and without consideration of these variables (Schug et al, 2020).
Pain and Its Management in Older Adults
Published in K. Rao Poduri, Geriatric Rehabilitation, 2017
Annie Philip, Diya Goorah, Rajbala Thakur
As a rule, the basal infusion should not exceed 20%–30% of the total available hourly dose. The most common opioid used is morphine followed by hydromorphone and fentanyl. The usual dose for morphine is a loading dose of 0.1–0.3 mg/kg in divided doses. One-tenth of the total loading dose can be used as a bolus every 10–15 minutes on an as-needed basis. For example, if a patient needed 10 mg of morphine to be comfortable, the prn bolus should be set at 1 mg every 10–15 minutes. Dosing for hydromorphone or fentanyl can be extrapolated using equianalgesic charts. Intravenous PCA is a safe and effective modality for use in cognitively intact older adults albeit they are able to understand and participate in their care, hence appropriate selection is very important.23
Pharmacology of opioids
Published in Pamela E. Macintyre, Stephan A. Schug, Acute Pain Management, 2014
Pamela E. Macintyre, Stephan A. Schug
All full μ agonists are capable of producing the same degree of pain relief. Therefore, they can theoretically be made equianalgesic if adjustments are made for dose and route of administration (Table 4.2). However, it must be noted that standard equianalgesic dose tables often present average data based on older single-dose studies of the drugs in a variety of clinical situations (Knotkova et al., 2009; Vallejo et al., 2011). Inter-individual differences in pharmacodynamics, pharmacokinetics, comorbidities, concurrent medications, age and genetics as well as incomplete cross-tolerance between opioids in patients on long-term opioid therapy, are just some of the variables that can have a significant effect on the total daily doses that may be required (Knotkova et al., 2009; Vallejo et al., 2011).
Opioid MOP receptor agonists in late-stage development for the treatment of postoperative pain
Published in Expert Opinion on Pharmacotherapy, 2022
Qiu Qiu, Joshua CJ Chew, Michael G Irwin
Another randomized, controlled, multicenter, phase-III clinical trial was conducted to investigate the efficacy of M6G in the treatment of postoperative pain after major abdominal surgery. M6G (0.42 mg/kg) or morphine (0.14 mg/kg) was given 30–60 min prior to the end of surgery. These doses were proposed to be equianalgesic. Postoperatively, PCA was prescribed for 24–48 hours (2 mg bolus of M6G or 1 mg of morphine, lockout time 5 min). The slow time-to-peak-effect caused twice as many M6G subjects (16.8% vs 8.8%) to withdraw from the clinical trial due to early, unsatisfactory pain control. Patients who did not withdraw had equivalent analgesia. The loading dose administered 30–60 min prior to the end of surgery appeared appropriate for morphine but was not altered for M6G’s onset time. M6G has a longer duration of action and demonstrated less PCA use in the later phases of postoperative pain management [87].
An update on the safety of prescribing opioids in pediatrics
Published in Expert Opinion on Drug Safety, 2019
Jagroop M. Parikh, Patricia Amolenda, Joseph Rutledge, Alexandra Szabova, Vidya Chidambaran
Extended use of one opioid results in low efficacy for the medication. In these cases, switching to another opioid in an equianalgesic dose may be considered. Table 1 depicts pediatric dosing guidelines for opioids. Opioid rotation is a strategy also used when there is a need for a different potency, a lowered opioid dose, use of a smaller quantity, and decreased intolerable side effects, when allow for use of a different formulation (for example, subcutaneous instead of intravenous), or because of practical considerations such as cost. Due to incomplete opioid cross-tolerance, the dose of the new opioid should be decreased by approximately 25–50% to minimize adverse effects and then the dose may be titrated to adequate pain control or supplemented with breakthrough medication doses for rescue analgesia. If the starting opioid has been escalated recently after a prolonged period of stability, then a dose closer to the previous stable level may be a more appropriate place to start [24,25]. In our clinical experience, many appropriate candidates for opioid rotation have chronic use of opioids, and while there are tables to calculate opioid analgesic equivalency, these tables are often based on opioid-naive patients and reflect variable patient populations.
Sentanyl: a comparison of blood fentanyl concentrations and naloxone dosing after non-fatal overdose
Published in Clinical Toxicology, 2022
Alex J. Krotulski, Brittany P. Chapman, Sarah J. Marks, Sam T. Ontiveros, Katharine Devin-Holcombe, Melissa F. Fogarty, Hai Trieu, Barry K. Logan, Roland C. Merchant, Kavita M. Babu
We searched the literature for techniques to provide a weighted composite of the quantitation of non-fentanyl opioids and their contribution to the overdose without success. In an exploratory analysis (included in the Supplementary Appendix), we used equianalgesic principles for opioid dosing.