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Pharmacology
Pediatric and Elderly considerations
Question | Answer |
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Why consider pediatric and elderly | Most info about drugs has been from healthy adult testing. Only about 25% of drugs are FDA approved for indications in children, but 75% are used. |
Peds differences in absorption | Usually more effective as child grows from neonate through childhood. Many GI system disorders at birth, infancy. Enzyme levels and intestinal flora less. Skin is more thin & porous so many more systemic effects from topical drugs |
Peds differences in distribution | Body fluid composition: Child 70%-Adult 50-60%. Increase risk of dehydration due to high body water. Very young have less protein binding sites-more free drug in plasma. Blood brain barrier less mature so CNA may be effected. |
Peds metabolism | Generally carried out in liver*** Wide variables child to child. Liver immature in neonate until 1-2 months. <2 yrs have less hepatic enzymes/slower metabolism. Children inherently have higher metabolic rate. |
Peds excretion*** | <9 months have lower GFR and renal tubular function. Higher risk for accumulation. Water needed to assure excretion-watch hydration status. |
Peds impact on drug dosage | Until 2 yrs, require higher doses of water soluble meds. Children are more likely to get dehydrated b/c they have higher amounts of extra cellular fluid. However, require LESS of a dose for fat soluble meds. Less protein receptor sites. |
Nursing responsibility | Most meds are based on weight. Body surface area may also be used-Better b/c it takes into account body composition**. IV route more predictable that other routes. Must know developmental & cognitive differences for age. Teach safety, involve family. |
BSA Calculator | For pediatric client, many drug dosages based on body surface area. Many PDA drug programs have calculator included in program. |
Elderly considerations | 70% of those >65 take at least 2 prescribed meds daily. Many take >8. Adverse reactions/interactions increase with number of drugs. 3-7x more likely than younger persons to have interactions |
Polypharmacy | Administration of many drugs together-intensified drug effects & interactions. Occurs b/c of multiple providers, OTC and herbal meds, share meds. Discontinued drugs not stopped. |
Hepatic | Less total liver function. Decreased enzyme function. Decreased blood flow. Leads to slow drug metabolism. More drug can accumulate in system and lead to drug toxicity |
Renal changes in elderly | Decreased GFR. Drugs excreted less completely. Accumulation leading to toxicity more likely. Most effected: narcotics & benzodiazepines. Creatinine clearance normal: 80-130ml/min. Elderly have decreased ability to excrete drugs |
Elderly Distribution | Decrease protein binding sites means increased free drug. Decrease in body water and increase in body fat. Drugs with high protein binding and/or fat soluble and/or long half life means increased risk of accumulation and toxicity** |
Elderly metabolism | Decrease liver blood flow, decrease enzyme process |
Elderly excretion | Decrease cardiac output, decrease GFR, decreased creatinine clearance. |
Elderly Pharmacokinetics | Overall, less able to absorb, metabolize, and excrete drugs |
Elder pharmacodynamics | Decreased receptor affinity and sensitivity. Generally need lower dose of drug or give less frequently. |
When deciding doses in elderly | Start slow!! low dose, then increase as needed. Go Slow! Consider rate of metabolism. |
Nursing considerations in elderly | Assess factors for noncompliance or lack of effectiveness: too many meds, failure to understand purpose, reason, or instructions, impaired memory, mobility, dexterity, visual or hearing problems, cost of meds, side effects |
Elderly may present with different signs of drug interactions | Delirium, agitation, incontinence, falls, depression, unusual fatigue, loss of appetite, weight loss |
Teaching considerations for elderly | Assess for visual and hearing abilities, speak clearly, face client, use large print in bright colors for printed info, assist to develop easy dosing schedule, use short time periods for teaching, teach-back method, get family/caregiver involved |