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Paediatric HIV Care

Paediatric HIV Care. UK-CAB - 28 Jan 2005 HIV i-Base. Background 1. Three years after the first descriptions (in 1981) of adult AIDS cases, similar disease characteristics were reported in children

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Paediatric HIV Care

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  1. Paediatric HIV Care UK-CAB - 28 Jan 2005 HIV i-Base www.i-Base.info

  2. Background 1 • Three years after the first descriptions (in 1981) of adult AIDS cases, similar disease characteristics were reported in children • Early 80s – most HIV+ children infected by blood transfusion (greatly reduced following the introduction of HIV specific antibody tests in 1985) • Since the early 90s the number of vertically infected children increased - approx 1200 in UK • Approx 950 HIV+ children in UK now • With ARV treatment transmission is now <1% www.i-Base.info

  3. Background 2In general: • HIV progresses more rapidly in children than in adults • Very high CD4 compared to adults (CD4%) More rapid decrease of CD4 cells  Higher viral load at same CD4 count Impaired growth www.i-Base.info

  4. CD4 % Lymphocytes are white blood cells (B cells and T cells)2 main types of T-cells: T-4 cells and T-8 cellsAbsolute CD4 count used to be the product of Total Lymphocytes and percentage that are CD4 (pre 1996, now CD4 cells are counted)The CD4% is the % of T-cells that are CD4 cellsHIV-negative : normal = 35-40% www.i-Base.info

  5. CD4 % <12 mo 1-5 yrs 6-12 yrscat 1 >1500 >1000 >500no supp >25% >25% >25%Cat 2 750-1500 500-1000 200-500mod 15-24% 15-24% 15-24%Cat 3 <750 <500 <200severe <15% <15% <15% www.i-Base.info

  6. CD4 % CD4% is useful in adult care - less variability but does not add any information to prediction of risk of illnessCD4% is ESSENTIAL in paediatric care www.i-Base.info

  7. HoweverWith effect ARV treatment:• mortality rates declining from 5.4% in 1995 to 1% in 1998.Children have an increased ability to recover from the damage caused by HIV. www.i-Base.info

  8. On HAARTChildren experience significant CD4 increases – 320 to 650 cells in the first year of treatment (vs adults 100 to 250) - but this dependent on age and limitations of CD4 count • more naïve cells than adults • Importance of age - ie the younger you are, the more likely to get higher numbers of CD4 cells • CD4 can increase to normal or near normal levels even with detectable viral load Some ‘miraculous’ results, though not universally successful www.i-Base.info

  9. How are children different?Different immunology• Immature immune system• Functioning thymus• Higher level and more variation of CD4 cells (this declines with age)Different pattern of HIV RNA• Decline of HIV viral load up to 5 yearsDifferent metabolism• Different absorption rates to adults• Different elimination rates• Metabolism changing at different ages www.i-Base.info

  10. Log10 HIV-1 RNA plotted against age with fitted line and 95% CI 6 5 Log10 RNA copies/ml 4 3 0 2 4 6 8 10 Age in years www.i-Base.info

  11. Children’s clinical trialsMany questions about treatment for HIV can be answered in adult trials and so it is unnecessary to repeat all trials in children. This has been controversial in the past. (viral load etc)PENTA (Paediatric European Network for Treatment of AIDS)http://www.ctu.mrc.ac.uk/penta/PACTG (Paediatric AIDS Clinical Trials Group)http://pactg.s-3.com/ www.i-Base.info

  12. Clinical trials in children • Issues • Tolerability and toxicity • When to treat • Choice of endpoints for efficacy • Problems • Limited numbers of children (almost all trials underpowered for age) • Limited anti-HIV drugs with paediatric formulations • Need to study pharmacokinetics of agents in different age groups www.i-Base.info

  13. Clinical Trials in Children • Focus on questions specific to children • Address issues of pharmacokinetics, toxicity and tolerability • Multinational collaborations (legal, cultural) • Address severalquestions at a time • Different ethical issues (ie recent GSK report in NYC) • Close collaboration with adults www.i-Base.info

  14. ARVs used in children NRTIs Abacavir (ABC) - oral solution Didanosine (ddI) - powder for oral solution Lamivudine (3TC) - oral solution Stavudine (d4T) - oral solution Zidovudine (ZDV, AZT) - oral solution Tenofovir - crushed tablets FTC NNRTIs Nevirapine (NVP) - suspension Efavirenz (EFV) - syrup >3 years PIs Nelfinavir (NFV) - powder for oral suspension Lopinavir/r (LPV/r) - oral solution >2 years Ritonavir (RTV) - oral solution Amprenavir (APV) - oral solution >3 years No liquid formulation Indinavir (IDV) - not from Merck Saquinavir (SQV) EIs T-20 - 50 children in study but rarely used if other choices available www.i-Base.info

  15. Dosing • Paediatric dosing is based on limited data • It is liable to change as new information becomes available • Use in clinical practice can often differ from doses recommended in licensed SPC www.i-Base.info

  16. Dosing/ PK Adult doses provide the reference point for paediatric doses  Either body weight or body surface area (BSA) are used to adjust doses For a ‘typical’ 5 year old a BSA calculated dose could be over 50% greater than one adjusted by weightFor AZT this 5 year old would receive a dose of 80mg with a mg/kg adjustment vs a dose of 140mg with a BSA adjustment www.i-Base.info

  17. Calculating BSABody Surface Area (BSA) can be calculated with the following equation: BSA (m2)=√ (Height (cm) X Weight (kg) /3600) www.i-Base.info

  18. Penta 7 Study Design: A multicentre phase I/II non comparative study of ddI, D4T, NFV in infants < 12 weeks of age, without AIDS. Objectives:To describe the tolerability, toxicity & antiviral activity of early treatment Nelfinavir started at 120 mg/kg/day Increased to 150/kg/day (this represents 5 times the equivalent adult dose!) AT 24 weeks <50 log10 copies/ml in only 3/12 (25%) This study was stopped by it’s DSMB www.i-Base.info

  19. When to start?PENTA Guidelines 2002 1 Always start ART if Clinical stage C or CD4 <15% 2 Consider ART if Clinical stage B or CD 4 <20% or High VL (>6 log if age < 1 year, >5 log if age over 1 year) 3 Defer ART if Stage N or A disease, and CD4 > 20 %, and,Low VL (<6 log if age < 1year, and <5 log if age over 1 year) www.i-Base.info

  20. Issues to consider when starting therapy in children • Parents wishes • Likelihood of good long term adherence • What formulations could this child take? • What PK data are available? • What drugs are other family members on? www.i-Base.info

  21. Advantages Allow normal development of the immune system Positive effect on long-term natural history (especially for babies born to treated mothers) Possibility to clear infection (babies)? Reset set point after primary infection, if stop Disadvantages Some children don’t need HAART for many years Long term effects of ART on QoL Short and long term toxicity Getting the right dose!!! Possibility to develop resistance (inadequate PK, adherence) and reduce future HAART options Loose HIV specific immune responses (babies)? Starting therapy early www.i-Base.info

  22. Early therapy for infants • If decide to start early: • Resistance testing at baseline if mother on ART • Choose regimen based on tolerability and PK • Support for adherence • Think about management for toxicity, failure, success • If decide to defer: • Monitor clinical, growth, CD4 and HIV RNA • Base decision on rate of change as well as absolutes www.i-Base.info

  23. Practical matters • food intake requirements • sleep requirements • dosage issues with teaspoons / liquids • formulation of medications • children vomit more easily • accidental overdose • Pill/liquid burden • Ease of administration • With/without food • Number of times per day • Creative use of drug-drug interactions www.i-Base.info

  24. Adherence • Particularly difficult issue in children Dependent both on the child, and on the parent/carer Dosing schedule - number and size of pills Taste of liquid or powder formulations Age of the child  Fears regarding disclosure  Awareness of their diagnosis • Adherence support • Age appropriate charts etc • Pill swallowing lessons • G-tubes www.i-Base.info

  25. PharmacokineticsDefinition: ‘The action of drugs in the body, including the processes of absorption, transformation, distribution to tissues, duration of action and elimination. • Age dependent • Depends on surface area • Variability • NNRTI’s and PI’s cleared more rapidly in children • Dosing in puberty? www.i-Base.info

  26. Changing baseline PK body water liver function renal gastric acid body fat preterm full 1 m 3 m 1 y 6 y Adult www.i-Base.info

  27. Lopinavir Concentrations(Data from Liverpool TDM Service) www.i-Base.info

  28. Nevirapine Concentrations(Data from Liverpool TDM Service) www.i-Base.info

  29. Reasons to consider TDM Adults Kids Y Y Y Y Y Y N Y N Y • dose & plasma relationship is unpredictable • concentration-effect relationship exists • efficacy / toxicity not immediately obvious • changing baseline PK • practical dosing difficulties www.i-Base.info

  30. Limitations of TDM • Highly dependent on information on time of dose • Only reflection of situation before visit) • Only one drug in the combination • Difficulty taking blood • PIs are highly bound to protein; protein levels may vary within and between patients • Compartments - only measuring blood plasma • Optimal frequency of sampling unknown • example: wk 4, 8, 12, then every 12 weeks www.i-Base.info

  31. Models of care • St Mary’s family clinic, London • Established in 1993 as family HIV clinic • Families can be seen in a single hospital visit • Inpatient and outpatient • Holistic model - multidisciplinary team including: psychologist, physiotherapist, dietician, specialist health visitor, social worker as well as HIV paediatricians, adult clinician, obstetrician. pharmacist and clinical nurse specialist • 85% clinic population from sub-saharan Africa www.i-Base.info

  32. Sophia Children’s Hospital, University of Rotterdam • Created in 1997 by group of Dutch paediatricians • Multidisciplinary study group • Over 40 kids enrolled in a protocol using IDV/ZDV/3TC - all comers ‘Research questions should only be raised when they serve to improve the quality of life with children’ Ronald de Groot www.i-Base.info

  33. Issues for advocates and parents • Individuality of any situation • Relationship to research from adult care • New formulations for pipeline and existing drugs • Ethical issues, especially trials • Ethical issues relating to PEG tubes • Implications of long-term treatment and toxicity www.i-Base.info

  34. Paediatric guidelines • PENTA: www.ctu.mrc.ac.uk/penta www.ctu.mrc.ac.uk/penta/guidelines.htm www.i-Base.info

  35. http://www.i-base.info www.i-Base.info

  36. www.i-Base.info

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