Special populations

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  • 1. Dosing Considerations for Vulnerable Populations
  • 2. Vulnerable Populations …
    • Are groups of patients with a high risk for adverse drug effects
    • Require careful dosing and/or medication selection
  • 3. At-Risk Groups Include
    • Men and women of reproductive age
    • Pregnant or breastfeeding women
    • Children and infants
    • Elderly patients
    • People with renal or hepatic disease
    • Obese or underweight patients
  • 4. Reproductive Age
    • In women: Drugs can affect fertility or damage ova
    • In men: Drugs can alter sperm quality and quantity
  • 5. Pregnancy
    • Pregnancy Categories: A, B, C, D, X
    • A: Studies in pregnant women have not shown a risk to the fetus
    • B: Animal studies have not shown harm to fetus or animal studies have shown fetal harm, but studies in pregnant women did not show risk
  • 6. Pregnancy (Cont’d)
    • Pregnancy Categories (Cont’d)
    • C: Animal studies show an adverse effect and there are no adequate studies in pregnant women or no animal studies have been conducted and there are no adequate studies in pregnant women
    • Many drugs fall into Category C!
  • 7. Pregnancy (Cont’d)
    • Pregnancy Categories (Cont’d)
    • D: Studies in pregnant women have shown a risk to the fetus; benefits may outweigh potential risks
    • X : Studies in animals and pregnant women have shown evidence of fetal harm; the drug is contraindicated in women who are or may become pregnant
  • 8. Pregnant Women
    • First Trimester
      • A woman is least likely to know she is pregnant
      • Teratogenic drugs may lead to fetal malformation or miscarriage
  • 9. Pregnant Women (Cont’d)
    • Third Trimester
      • Drugs may not be safely metabolized and excreted by the fetus
    • After Delivery
      • Infants no longer have the placenta to help with drug excretion, and drugs given before delivery may cause toxicity
  • 10. Pregnant Women (Cont’d)
    • For pregnant women who require medication, both mother and fetus must be considered
    • Weigh risks and benefits
    • Rule of thumb:
    • LOWEST EFFECTIVE DOSE
    • for the
    • SHORTEST PERIOD OF TIME
  • 11. Lactation
    • Many drugs are known or thought to be excreted in breast milk
    • Dose in breast milk will be low, but still may cause adverse effects in the infant
    • Some drugs interfere with milk supply
    • American Association of Pediatrics (AAP) lists drugs usually compatible with breastfeeding
    • http://aappolicy.aappublications.org/cgi/content/ full/pediatrics;108/3/776
  • 12. Lactation (Cont’d)
    • AAP encourages breastfeeding if drug is unlikely to cause harm
    • In poorer nations, bottle feeding may not be an alternative
    • Research medication at LactMed
    • http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT
  • 13. Pediatrics
    • Most drugs given to children <18 years have not been approved by the FDA for children
    • Must contain information for SAFE PEDIATRIC USE
  • 14. Pediatrics: Neonates and Preemies
    • Difficulty in dosing is secondary to
        • Immature function of body systems
        • Rapid weight changes
        • Progressive maturation of hepatic and renal function
  • 15. Pediatric Dosing
    • Doses for children are not automatically less than those for adults
    • Higher metabolic rate in children causes drugs to be processed more quickly
    • Higher doses are needed to maintain therapeutic blood levels
  • 16. Pediatric Dosing (Cont’d)
    • Medication doses are based on body weight or body surface area (BSA)
      • Body weight doses expressed as mg/kg
      • BSA doses expressed as mg/m 2
  • 17. Geriatrics
    • Adults over 55 have ↑ risk for toxic reactions
    • Age-related changes affect pharmacokinetics
          • Absorption
          • Distribution
          • Metabolism
          • Excretion
  • 18. Geriatrics (Cont’d)
    • Changes that affect pharmacokinetics
      • ↑ P ercentage of body fat
      • ↓ Lean muscle mass
      • ↓ Total body water
      • ↓ Protein
  • 19. Geriatrics (Cont’d)
      • ↓ GI motility and blood flow delays absorption and distribution
      • ↓ Hepatic and renal function delays metabolism and excretion
      • Leads to greater incidence of toxicity
      • Prescribe lowest possible dose at initiation of drug(s)
  • 20. Geriatrics (Cont’d)
    • Monitor for
      • Signs and symptoms of toxicity and side effects
      • Drug interactions
      • Usage and complications of OTCs and herbal drugs
      • Effectiveness
  • 21. Patients with Renal Disease
    • Kidneys are the m ajor organ of drug elimination
    • Failure to account for decreased renal function is a preventable source of adverse drug reactions
    • Assess
      • Creatinine clearance
      • BUN and creatinine
      • Medication blood levels
  • 22. Patients with Liver Disease
    • The liver is the m ajor organ of metabolism
    • The liver changes drugs from fat soluble to water soluble so that kidneys can excrete them
    • Liver damage leads to higher levels of active drug and more toxicity
  • 23. Patients with Liver Disease (Cont’d)
    • Monitor
      • Liver enzymes
      • Albumin, total protein
    • Assess patient for
      • Enlarged liver
      • Ascites, jaundice
  • 24.
    • Obese Patients
      • Drug dosing often based on body weight
      • Some drugs do not penetrate fatty tissues
      • To prevent toxicity when giving drugs that do not penetrate fatty tissue (e.g., digoxin) determine dose by ideal body weight or estimated lean body mass
    Patients with Extremes of Body Size
  • 25.
    • Underweight Patients
    • Patients likely to be underweight
      • Chronic alcoholics
      • Patients with AIDS
      • Patients terminally ill with cancer and other debilitating illnesses
      • Amputations
    • No standard formula for calculating dose in underweight patients — watch for toxicity
    Patients with Extremes of Body Size (Cont’d)