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Gastine S, Morse JD, Leung MT, Wong ICK, Howard RF, Harrop E, Liossi C, Standing JF, Jassal SS, Hain RD, Skene S, Oulton K, Law SL, Quek WT, Anderson BJ. Diamorphine pharmacokinetics and conversion factor estimates for intranasal diamorphine in paediatric breakthrough pain:systematic review. BMJ Support Palliat Care 2024; 13:e485-e493. [PMID: 35184039 DOI: 10.1136/bmjspcare-2021-003461] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/26/2022] [Indexed: 12/22/2022]
Abstract
BACKGROUND Intranasal diamorphine is a potential treatment for breakthrough pain but few paediatric data are available to assist dose estimation. AIM To determine an intranasal diamorphine dose in children through an understanding of pharmacokinetics. DESIGN A systematic review of the literature was undertaken to seek diamorphine pharmacokinetic parameters in neonates, children and adults. Parenteral and enteral diamorphine bioavailability were reviewed with respect to formation of the major metabolite, morphine. Clinical data quantifying equianalgesic effects of diamorphine and morphine were reviewed. REVIEW SOURCES PubMed (1960-2020); EMBASE (1980-2020); IPA (1973-2020) and original human research studies that reported diacetylmorphine and metabolite after any dose or route of administration. RESULTS The systematic review identified 19 studies: 16 in adults and 1 in children and 2 neonatal reports. Details of study participants were extracted. Age ranged from premature neonates to 67 years and weight 1.4-88 kg. Intranasal diamorphine bioavailability was predicted as 50%. The equianalgesic intravenous conversion ratio of morphine:diamorphine was 2:1. There was heterogeneity between pharmacokinetic parameter estimates attributed to routes of administration, lack of size standardisation, methodology and pharmacokinetic analysis. Estimates of the pharmacokinetic parameters clearance and volume of distribution were reduced in neonates. There were insufficient paediatric data to characterise clearance or volume maturation of either diamorphine or its metabolites. CONCLUSIONS We estimate equianalgesic ratios of intravenous morphine:diamorphine 2:1, intravenous morphine:intranasal diamorphine 1:1 and oral morphine:intranasal diamorphine of 1:3. These ratios are based on adult literature, but are reasonable for deciding on an initial dose of 0.1 mg/kg in children 4-13 years.
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Affiliation(s)
- Silke Gastine
- Great Ormond St Institute of Child Health, University College London, London, UK
| | - James D Morse
- Department of Pharmacology & Clinical Pharmacology, The University of Auckland Faculty of Medical and Health Sciences, Auckland, New Zealand
| | - Miriam Ty Leung
- Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, Hong Kong
| | - Ian Chi Kei Wong
- Research Department of Practice and Policy, University College London School of Pharmacy, London, UK
| | - Richard F Howard
- Department of Anaesthesia and Pain Medicine, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | | | - Christina Liossi
- School of Psychology, University of Southampton, Southampton, UK
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Joseph F Standing
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
- Department of Immunity and Inflammation, University College London, London, UK
| | - Satbir Singh Jassal
- Palliative Care, Rainbows Hospice for Children and Young Adults, Loughborough, UK
| | - Richard D Hain
- All-Wales Managed Clinical Network in Paediatric Palliative Medicine, Cardiff and Vale University Health Board, Cardiff, UK
| | - Simon Skene
- Faculty of Arts and Human Sciences, Surrey Clinical Trials Unit, University of Surrey, Guildford, UK
| | - Kate Oulton
- Centre for Outcomes and Experience Research in Children's Health, Illness and Disability, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Siew L Law
- Research Department of Practice and Policy, University College London School of Pharmacy, London, UK
| | - Wan T Quek
- Research Department of Practice and Policy, University College London School of Pharmacy, London, UK
| | - Brian J Anderson
- Department of Anaesthesiology, The University of Auckland Faculty of Medical and Health Sciences, Auckland, New Zealand
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Bardol M, Pan S, Walker SM, Standing JF, Dawes JM. Pharmacokinetic pharmacodynamic modeling of analgesics and sedatives in children. Paediatr Anaesth 2023; 33:781-792. [PMID: 37341161 PMCID: PMC10947261 DOI: 10.1111/pan.14712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 05/18/2023] [Accepted: 05/21/2023] [Indexed: 06/22/2023]
Abstract
Pharmacokinetic pharmacodynamic modeling is an important tool which uses statistical methodology to provide a better understanding of the relationship between concentration and effect of drugs such as analgesics and sedatives. Pharmacokinetic pharmacodynamic models also describe between-subject variability that allows identification of subgroups and dose adjustment for optimal pain management in individual patients. This approach is particularly useful in the pediatric population, where most drugs have received limited evaluation and dosing is extrapolated from adult practice. In children, the covariates of weight and age are used to describe size- and maturation-related changes in pharmacokinetics. It is important to consider both size and maturation in order to develop an accurate model and determine the optimal dose for different age groups. An adequate assessment of analgesic and sedative effect using pain scales or brain activity measures is essential to build reliable pharmacokinetic pharmacodynamic models. This is often challenging in children due to the multidimensional nature of pain and the limited sensitivity and specificity of some measurement tools. This review provides a summary of the pharmacokinetic and pharmacodynamic methodology used to describe the dose-concentration-effect relationship of analgesics and sedation in children, with a focus on the different pharmacodynamic endpoints and the challenges of pharmacodynamic modeling.
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Affiliation(s)
- Maddlie Bardol
- Infection, Immunity and Inflammation, Great Ormond Street Institute of Child HealthUniversity College LondonLondonUK
| | - Shan Pan
- Infection, Immunity and Inflammation, Great Ormond Street Institute of Child HealthUniversity College LondonLondonUK
| | - Suellen M. Walker
- Department of Anaesthesia and Pain MedicineGreat Ormond St Hospital NHS Foundation TrustLondonUK
- Developmental Neurosciences Program, UCL Great Ormond St Institute of Child HealthUniversity College LondonLondonUK
| | - Joseph F. Standing
- Infection, Immunity and Inflammation, Great Ormond Street Institute of Child HealthUniversity College LondonLondonUK
- Department of PharmacyGreat Ormond St Hospital NHS Foundation TrustLondonUK
| | - Joy M. Dawes
- Infection, Immunity and Inflammation, Great Ormond Street Institute of Child HealthUniversity College LondonLondonUK
- Department of Anaesthesia and Pain MedicineGreat Ormond St Hospital NHS Foundation TrustLondonUK
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Morse JD, Cortinez LI, Anderson BJ. Considerations for Intravenous Anesthesia Dose in Obese Children: Understanding PKPD. J Clin Med 2023; 12:jcm12041642. [PMID: 36836174 PMCID: PMC9960599 DOI: 10.3390/jcm12041642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/09/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023] Open
Abstract
The intravenous induction or loading dose in children is commonly prescribed per kilogram. That dose recognizes the linear relationship between volume of distribution and total body weight. Total body weight comprises both fat and fat-free mass. Fat mass influences the volume of distribution and the use of total body weight fails to recognize the impact of fat mass on pharmacokinetics in children. Size metrics alternative to total body mass (e.g., fat-free and normal fat mass, ideal body weight and lean body weight) have been proposed to scale pharmacokinetic parameters (clearance, volume of distribution) for size. Clearance is the key parameter used to calculate infusion rates or maintenance dosing at steady state. Dosing schedules recognize the curvilinear relationship, described using allometric theory, between clearance and size. Fat mass also has an indirect influence on clearance through both metabolic and renal function that is independent of its effects due to increased body mass. Fat-free mass, lean body mass and ideal body mass are not drug specific and fail to recognize the variable impact of fat mass contributing to body composition in children, both lean and obese. Normal fat mass, used in conjunction with allometry, may prove a useful size metric but computation by clinicians for the individual child is not facile. Dosing is further complicated by the need for multicompartment models to describe intravenous drug pharmacokinetics and the concentration effect relationship, both beneficial and adverse, is often poorly understood. Obesity is also associated with other morbidity that may also influence pharmacokinetics. Dose is best determined using pharmacokinetic-pharmacodynamic (PKPD) models that account for these varied factors. These models, along with covariates (age, weight, body composition), can be incorporated into programmable target-controlled infusion pumps. The use of target-controlled infusion pumps, assuming practitioners have a sound understanding of the PKPD within programs, provide the best available guide to intravenous dose in obese children.
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Affiliation(s)
- James Denzil Morse
- Department of Anaesthesiology, University of Auckland, Park Road, Auckland 1023, New Zealand
| | - Luis Ignacio Cortinez
- División Anestesiología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| | - Brian Joseph Anderson
- Department of Anaesthesiology, University of Auckland, Park Road, Auckland 1023, New Zealand
- Department of Anaesthesia, Auckland Children’s Hospital, Park Road, Private Bag 92024, Auckland 1023, New Zealand
- Correspondence: ; Tel.:+64-9-3074903; Fax: +64-9-3078986
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Svedmyr A, Hack H, Anderson BJ. Interactions of the protease inhibitor, ritonavir, with common anesthesia drugs. Paediatr Anaesth 2022; 32:1091-1099. [PMID: 35842922 PMCID: PMC9543968 DOI: 10.1111/pan.14529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 07/12/2022] [Accepted: 07/13/2022] [Indexed: 11/27/2022]
Abstract
The protease inhibitor, ritonavir, is a strong inhibitor of CYP 3A. The drug is used for management of the human immunovirus and is currently part of an oral antiviral drug combination (nirmatrelvir-ritonavir) for the early treatment of SARS-2 COVID-19-positive patients aged 12 years and over who have recognized comorbidities. The CYP 3A enzyme system is responsible for clearance of numerous drugs used in anesthesia (e.g., alfentanil, fentanyl, methadone, rocuronium, bupivacaine, midazolam, ketamine). Ritonavir will have an impact on drug clearances that are dependent on ritonavir concentration, anesthesia drug intrinsic hepatic clearance, metabolic pathways, concentration-response relationship, and route of administration. Drugs with a steep concentration-response relationship (ketamine, midazolam, rocuronium) are mostly affected because small changes in concentration have major changes in effect response. An increase in midazolam concentration is observed after oral administration because CYP 3A in the gastrointestinal wall is inhibited, causing a large increase in relative bioavailability. Fentanyl infusion may be associated with a modest increase in plasma concentration and effect, but the large between subject variability of pharmacokinetic and pharmacodynamic concentration changes suggests it will have little impact on an individual patient, especially when used with adverse effect monitoring. It has been proposed that drugs that have no or only a small metabolic pathway involving the CYP 3A enzyme be used during anesthesia, for example, propofol, atracurium, remifentanil, and the volatile agents. That anesthesia approach denies children of drugs with considerable value. It is better that the inhibitory changes in clearance of these drugs are understood so that rational drug choices can be made to tailor drug use to the individual patient. Altered drug dose, anticipation of duration of effect, timing of administration, use of reversal agents and perioperative monitoring would better behoove children undergoing anesthesia.
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Affiliation(s)
- Anders Svedmyr
- Dept AnaesthesiaStarship Children's HospitalAucklandNew Zealand
| | - Henrik Hack
- Dept AnaesthesiaStarship Children's HospitalAucklandNew Zealand
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Morse JD, Cortinez LI, Anderson BJ. Pharmacokinetic Pharmacodynamic Modelling Contributions to Improve Paediatric Anaesthesia Practice. J Clin Med 2022; 11:jcm11113009. [PMID: 35683399 PMCID: PMC9181587 DOI: 10.3390/jcm11113009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 12/10/2022] Open
Abstract
The use of pharmacokinetic-pharmacodynamic models has improved anaesthesia practice in children through a better understanding of dose-concentration-response relationships, developmental pharmacokinetic changes, quantification of drug interactions and insights into how covariates (e.g., age, size, organ dysfunction, pharmacogenomics) impact drug prescription. Simulation using information from these models has enabled the prediction and learning of beneficial and adverse effects and decision-making around clinical scenarios. Covariate information, including the use of allometric size scaling, age and consideration of fat mass, has reduced population parameter variability. The target concentration approach has rationalised dose calculation. Paediatric pharmacokinetic-pharmacodynamic insights have led to better drug delivery systems for total intravenous anaesthesia and an expectation about drug offset when delivery is stopped. Understanding concentration-dependent adverse effects have tempered dose regimens. Quantification of drug interactions has improved the understanding of the effects of drug combinations. Repurposed drugs (e.g., antiviral drugs used for COVID-19) within the community can have important effects on drugs used in paediatric anaesthesia, and the use of simulation educates about these drug vagaries.
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Affiliation(s)
- James D. Morse
- Department of Anaesthesiology, University of Auckland, Park Road, Auckland 1023, New Zealand;
| | - Luis Ignacio Cortinez
- División Anestesiología, Escuela de Medicina, Pontificia Universidad Católica de Chile, San Diego de Chile 8331150, Chile;
| | - Brian J. Anderson
- Department of Anaesthesiology, University of Auckland, Park Road, Auckland 1023, New Zealand;
- Correspondence: ; Tel.: +64-9-3074903; Fax: +64-9-3078986
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Piirainen P, Kokki H, Kokki M. Epidural Oxycodone for Acute Pain. Pharmaceuticals (Basel) 2022; 15:643. [PMID: 35631469 PMCID: PMC9144954 DOI: 10.3390/ph15050643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 05/16/2022] [Accepted: 05/19/2022] [Indexed: 02/01/2023] Open
Abstract
Epidural analgesia is commonly used in labour analgesia and in postoperative pain after major surgery. It is highly effective in severe acute pain, has minimal effects on foetus and newborn, may reduce postoperative complications, and enhance patient satisfaction. In epidural analgesia, low concentrations of local anaesthetics are combined with opioids. Two opioids, morphine and sufentanil, have been approved for epidural use, but there is an interest in evaluating other opioids as well. Oxycodone is one of the most commonly used opioids in acute pain management. However, data on its use in epidural analgesia are sparse. In this narrative review, we describe the preclinical and clinical data on epidural oxycodone. Early data from the 1990s suggested that the epidural administration of oxycodone may not offer any meaningful benefits over intravenous administration, but more recent clinical data show that oxycodone has advantageous pharmacokinetics after epidural administration and that epidural administration is more efficacious than intravenous administration. Further studies are needed on the safety and efficacy of continuous epidural oxycodone administration and its use in epidural admixture.
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Affiliation(s)
- Panu Piirainen
- Department of Anesthesiology, Surgery and Intensive Care, Oulu University Hospital, 90220 Oulu, Finland;
| | - Hannu Kokki
- Institute of Clinical Medicine, School of Medicine, Faculty of Health Sciences, Kuopio Campus, University of Eastern Finland, 70210 Kuopio, Finland;
| | - Merja Kokki
- Department of Anaesthesiology and Intensive Care, Kuopio University Hospital, 70210 Kuopio, Finland
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Morse JD, Cortinez LI, Meneely S, Anderson BJ. Propofol context-sensitive decrement times in children. Paediatr Anaesth 2022; 32:396-403. [PMID: 34971456 DOI: 10.1111/pan.14391] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/10/2021] [Accepted: 12/28/2021] [Indexed: 11/29/2022]
Abstract
Plasma drug concentration is the variable linking dose to effect. The decrement time required for plasma concentration of anesthetic agents to decrease by 50% (context-sensitive half-time) correlates with the time taken to regain consciousness. However, the decrement time to consciousness may not be 50%. An effect compartment concentration is associated more closely with return of consciousness than plasma concentration. An alternative decrement time, the time required for propofol to decrease to a predetermined effect compartment concentration associated with movement (eg, 2 µg.ml-1 ), was used to simulate time for the concentration to decrease from steady state at a typical targeted effect compartment concentration 3.5 µg.ml-1 in children. These times were short and reflected a decrement time to consciousness (CSTAWAKE ) increase that was small with longer infusion time. CSTAWAKE ranged from 7.5 min in 1-year-old infant given propofol for 15 min to 13.5 min in a 15-year-old adolescent given a 2-hour infusion. Changes in decrement time with age reflect maturation of drug clearance. Neonates had prolonged increment times, 10 min after 15 min infusion and 18 min after 120 min infusion using a target concentration of 3.5 µg.ml-1 . Decrement times to a targeted arousal concentration are context-sensitive. Use of a higher target concentration of 6 µg.ml-1 doubled decrement times. Decrement times are associated with variability: delayed recovery beyond these simulated times is likely more attributable to the use of adjuvant drugs or the child's clinical status. An understanding of propofol decrement times can be used to guide recovery after anesthesia.
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Affiliation(s)
- James D Morse
- Department of Pharmacology & Clinical Pharmacology, Auckland University, Auckland, New Zealand
| | - Luis Ignacio Cortinez
- División Anestesiología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Stephen Meneely
- Department of Anaesthesia, Starship Children's Hospital, Auckland, New Zealand
| | - Brian J Anderson
- Department of Anaesthesiology, University of Auckland, Auckland, New Zealand
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