Pharm ch 11
Metabolism varies from child to child. Hepatic metabolic activity is lower in neonates, infant hepatic function matures about 1-2 months of age. More rapid metabolism in children may necessitate higher med dosages or shorter intervals to maintain concentrations. First-pass effect is the amount of med that is metabolized by the liver prior to availability to the tissues, must be considered. RECTAL ROUTE WILL AVOID THE FIRST-PASS EFFECT!!
Because meds are excreted more slowly in peds, drugs may accumulate and create toxic levels! Peds Pharamacodynamics: Mechanism of action including onset, peak, and duration
Gastric pH is alkaline @ birth with acid production beginning in the neonatal period-does not reach adult pH levels until 1-3 y.o.-low pH (acidic) = greater acidic drug absorption & high pH (alkaline) = greater basic drug absorption. Emptying time is generally prolonged in neonates & infants but increases with growth. Delayed emptying reduces the peak serum concentrations of medications. Breastfed infants may have longer GI transit times. Irregular peristalsis associated with immaturity, vomiting, or diarrhea decreases absorption time available for medications.
GI surface area is greater in children than adults which allows for more absorptive area in the stomach & intestines. Immature enzyme functioning-low lipase levels deter the absorption of lipid-soluble meds, microorganism colonization with the changing pH & flora create a different environment for absorption of oral meds. **Dehydration, cold temperatures, and alterations in cardiac status may impede absorption of meds at the tissue level. Topical meds may be altered thru the condition of the skin, for children, the skin is thinner and more porous, surface are is proportionately higher than adults; can increase the risk for systemic side effects!
Pediatric Evaluation: -Determine family member's knowledge concerning drug, drug dose, schedule for admin, and side effects -Determine child's physiologic and psychologic response -Determine therapeutic and adverse effects of drug(s)
Keep in mind that as children grow generally absorption of meds becomes more effective. Issue related to absorption must be considered in dosage and admin. Adolescence is unique in that absorption is decreased r/t to nutritional habits, changes in physical maturity, and hormonal changes!!! With oral meds - conditions in stomach and intestines such as gastric acidity, gastric emptying time, motility, GI surface are, enzyme levels, and intestinal flora. LACK OF MATURATION OF GI TRACT IS MOST PRONOUNCED IN NEONATES AND INFANTS!!!!!!!!!!!!
The increased body fluid proportion to weight allows for a greater volume for the medication to be distributed & a decreasing drug concentration. Until about 2 y.o., the peds client requires higher doses of water-soluble meds to achieve therapeutic levels. Younger clients also have higher levels of extracellular fluids, which increase the tendency for children to become dehydrated and change the distribution of water-soluble medications. **Less body fat causes the neonates & infants to require less fat-soluble medications relative to adults because fat-soluble drugs saturate fat tissue first, then body tissues-less fat=less med requirements.
Only free or unbound drugs are available for effect. Fewer protein receptor sites allows med to be more available for use & means a decrease dose is needed. Higher serum concentrations means higher risk of toxic effects. In neonates, high bilirubin levels may interfere with expected distribution-bilirubin combines with protein receptor sites; sites are unavailable for medication; higher circulating levels of the drug. The skin is more absorptive in young children and provides for rapid distribution of medication. Infants' blood-brain barriers are relatively immature, allowing medications to pass easily into nervous system tissue and increasing the likelihood for toxicity in young infants.
Pediatric - Nursing Implications: -Pediatric medication dosing/monitoring - monitor for effectiveness and toxicity -Careful calculation of doses!!!!! -Client identification -Developmental and cognitive differences: developmental vs. chronologic age -Maintain safety with minimal restraint -Pediatric med admin: adaptations to infants and children; route of admin -Age appropriate approaches: developmental care and atraumatic care
Pediatric - Adolescents: -Growth rate: hormonal changes, growth spurts, sleep requirements, metabolic rate changes -Cognitive level: progress from concrete to abstract reasoning -Perception of invulnerability: difficulty in perception of long-term consequences -Emotional development: risk-taking, questioning -Assess abilities to self-administer meds -Higher participation in care plan for chronic illnesses
Pediatric - Pharmacokinetics: Excretion: -Primarily in the kidneys; decreased renal blood flow in those < 9 months, decreased GFR, reduced renal tubular function -Adequate hydration is necessary for effective excretion!!!!!!
Pediatric - Pharmacodynamics: -The pharmacokinetics and differences in children affect the onset, peak, and duration!!!!! -The half-life of a med may be different in children than in adults!!! -Organ function, developmental implications, and admin issues impact pharmacodynamics!!!!!!
Pediatric pharmacology is limited by the available research: conclusions are typically extrapolated form adult studies -Research risks/informed consent for children -Ethical implications in research on children!!
Pediatric - Pharmacokinetics: -Absorption: Influenced by age, health status, weight, and route. PO factors: underlying disease, hydration status, and GI disorders. Absorption is affected by route of admin, gastric acidity, gastric emptying, gastric motility, gastrointestinal surface area, enzyme levels, and intestinal flora!!!!!! IM/Subcut absorption is affected by peripheral perfusion, effectiveness of circulation, dehydration, cold, and cardiac status. Topical absorption: the skin is thin and porous and may have systemic effects!!!!!!!!!!
Pediatric - Pharmacokinetics: Distribution: -Body fluid composition (neonates and young infants - 70% water, gradually decreases to 50-60% water) -Body tissue composition: neonates and young infants have less body fat -Protein-binding capability: neonates and young infants have less albumin and fewer receptor sites -Effectiveness of barriers: the skin is more absorptive in peds and infants blood-brain barriers are immature
Pediatric - Pharmacokinetics: Metabolism: -Maturational level of the child: primarily metabolized in the liver; kidneys and lungs play small roles. Sustained decreases in level of hepatic enzymes result in slower metabolism in infants until age of 2! -First-pass effect: Oral meds may undergo some metabolism in the liver via the GI system before the drug is available to body tissues -Higher metabolic rate: May require a higher dose or shorter duration
Pediatric Planning: -Child receives correct drug dose based on complete assessment data
Pediatric Interventions: -Use appropriate references -Monitor child closely for side effects because of their immature liver and kidney function -Monitor usual behavior patterns to identify side effects -Communicate with health care provider -Correctly calculate dosage based on appropriate parameters!! -Client teaching (medication use, indications, side effects, dosages, and precautions for client and family, use of OTC drugs; report side effects immediately, keep meds out of reach of children, use child-restraint containers for meds)
Pediatric Pharmacology Assessment: -Accurately assess and record the age, weight, and height -Developmental age, health status, and history of drug use - Nutritional/hydration status -Cognitive level -Family/child understanding -Use of home/folk remedies
Pediatric Potential Nursing Diagnoses: -Delayed growth and development -Ineffective tissue perfusion -Impaired urinary elimination -Deficient knowledge -Risk for injury
Adolescence is a highly diverse period of growth and development. A group of adolescents of similar ages may manifest very different sizes, height-to-weight proportions, timing of secondary sex characteristics, and other indicators of physical maturity.
These differences may warrant individualization of doses based on weight or body surface area, even when the adolescent meets or exceeds the size of standard adults, an adjustment may be required in the dosage of a lipid-soluble medication because change in lean-to-fat body mass, especially in young adolescent males, coincide with physical maturation
Monitoring may include serum drug levels or clinical parameters. Calculation of doses is extremely important!!! Have 2 nurses check calculations!! Doses are usually based on weight, but may be based on BSA. Identification of the pt is vital!!! The ability of the child to understand is part of the developmental consideration. Family members may be utilized in order to administer meds. There are times when the education r/t the med will be directed to caregivers. Maintaining safety with minimal restraint is the best rule!!!!!
With peds, use oral syringes for PO meds. The smallest syringe for the dose helps to ensure the best measurement. IV gives the most predictable route. Delivery of therapeutic care thru the implementation of interventions that eliminate or minimize the psychological and physical distress experienced by children and their families in the health care system
