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Pharmacologic Principles part 2 of 2 James L. King, MSN, CRNA Life Span Considerations Life Span Considerations • • • • • Pregnancy Breast-feeding Neonatal Pediatric Geriatric Pregnancy • First trimester is the period of greatest danger for drug-induced developmental defects • Drugs diffuse across the placenta • FDA pregnancy safety categories Table 3-1 Pregnancy safety categories Breast-feeding • Breast-fed infants are at risk for exposure to drugs consumed by the mother • Consider risk-to-benefit ratio Flash Question: During patient teaching the nurse advises lactating mothers that drug effects may be minimized by taking medications A.Right after breastfeeding B.Two hours after breastfeeding C.One hour before breastfeeding D.Right before breastfeeding Rationale: • D: Taking a medication right after breastfeeding allows for the maximum amount of time for drug excretion before the next breastfeeding. Table 3-2 Classification of young patients Pediatric Considerations: Pharmacokinetics • Absorption • Gastric pH less acidic • Gastric emptying is slowed • Topical absorption faster through the skin • Intramuscular absorption faster and irregular Pediatric Considerations: Pharmacokinetics (cont'd) • Distribution • TBW 70% to 80% in full-term infants, 85% in premature newborns, 64% in children 1 to 12 years of age • Greater TBW means fat content is lower • Decreased level of protein binding • Immature blood-brain barrier Pediatric Considerations: Pharmacokinetics (cont'd) • Metabolism • Liver immature, does not produce enough microsomal enzymes • Older children may have increased metabolism, requiring higher doses • Other factors Pediatric Considerations: Pharmacokinetics (cont'd) • Excretion • Kidney immaturity affects glomerular filtration rate and tubular secretion • Decreased perfusion rate of the kidneys Summary of Pediatric Considerations • • • • Skin is thin and permeable Stomach lacks acid to kill bacteria Lungs lack mucus barriers Body temperatures poorly regulated and dehydration occurs easily • Liver and kidneys are immature, impairing drug metabolism and excretion Methods of Dosage Calculation for Pediatric Patients • Body surface area method • West nomogram • Body weight dosage calculations Pediatric Considerations: Medication Administration • • • • • • General interventions Infants Toddlers Preschoolers School-age children Adolescents Figure 3-1 West nomogram for infants and children. (Modified from data by E. Boyd and C.D. West. In Behrman RE, Kliegman RM, Jensen HB: Nelson textbook of pediatrics, ed 17, Philadelphia, 2004, Saunders.) Flash Question:Knowing that the albumin in neonates and infants has a lower binding capacity for medications, a health care provider would do which of the following to minimize the risk of toxicity? A.Decrease the amount of drug given B.Increase the amount of drug given C.Shorten the time interval between doses D.Administer the medication intravenously Rationale: • A: A lower binding capacity leaves more drug available for action; thus, a lower dose would be required to prevent toxicity. Geriatric Considerations • Geriatric: older than age 65 • Healthy People 2010: older than age 55 • Use of OTC medications • Polypharmacy Physiologic Changes in the Geriatric Patient • • • • Cardiovascular Gastrointestinal Hepatic Renal Table 3-4 Physiologic changes in the geriatric patient Geriatric Considerations: Pharmacokinetics • Absorption • Gastric pH less acidic • Slowed gastric emptying • Movement through GI tract slower • Reduced blood flow to the GI tract • Reduced absorptive surface area due to flattened intestinal villi Geriatric Considerations: Pharmacokinetics (cont'd) • Distribution • TBW percentages lower • Fat content increased • Decreased production of proteins by the liver, resulting in decreased protein binding of drugs Geriatric Considerations: Pharmacokinetics (cont'd) • Metabolism • Aging liver produces less microsomal enzymes, affecting drug metabolism • Reduced blood flow to the liver Geriatric Considerations: Pharmacokinetics (cont'd) • Excretion • Decreased glomerular filtration rate • Decreased number of intact nephrons Geriatric Considerations: Problematic Medications • • • • • • • Analgesics Anticoagulants Anticholinergics Antihypertensives Digoxin Sedatives and hypnotics Thiazide diuretics Flash Question: The physiologic changes that normally occur in the older adult have which of the following implications for the nurse who is assessing drug response in this patient? A.Drug half-life is lengthened B.Drug metabolism is faster C.Drug elimination is faster D.Protein binding is more efficient. Rationale: • A: Drug half-life is extended secondary to diminished liver and renal function in the elderly. Legal, Ethical, and Cultural Considerations U.S. Drug Legislation • 1906: Federal Food and Drug Act • 1912: Sherley Amendment (to the Federal Food and Drug Act of 1906) • 1914: Harrison Narcotic Act • 1938: Federal Food, Drug, and Cosmetic Act (revision of 1906 Act) U.S. Drug Legislation (cont'd) • 1951: Durham-Humphrey Amendment (to the 1938 act) • 1962: Kefauver-Harris Amendment (to the 1938 act) • 1970: Controlled Substance Act Table 4-1 Controlled substances: schedule categories Table 4-2 Controlled substances: categories, dispensing restrictions, and examples U.S. Drug Legislation (cont'd) • 1983: Orphan Drug Act • 1991: Accelerated drug approval New Drug Development • Investigational new drug (IND) application • Informed consent • Investigational drug studies • Expedited drug approval U.S. FDA Drug Approval Process • Preclinical investigational drug studies • Clinical phases of investigational drug studies • Phase I • Phase II • Phase III • Phase IV Legal and Ethical Principles • • • • • • Autonomy Beneficence Confidentiality Justice Nonmaleficence Veracity Ethical Nursing Practice • American Nurses Association (ANA) Code of Ethics for Nurses Flash Question: Ethically, a nurse has the responsibility to: A. Employ beneficence, the duty to do no harm to a patient B.Withhold information from the patient as requested by the family C.Impose his or her own values upon the patient when doing so would help the patient D.Transfer care of a patient to another professional nurse if caring for the patient would violate personal ethical principles Rationale: • D: Beneficence is the duty to do good; withholding information from a patient is not only unethical but illegal, and imposing your values onto a patient is never appropriate. However, if providing required care to a certain type of patient would violate your personal ethics, then it is your responsibility to transfer care of that patient to another professional nurse rather than not performing necessary care, which would be a form of abandonment. Cultural Considerations • Assess the influence of a patient’s cultural beliefs, values, and customs • Drug polymorphism • Compliance level with therapy • Environmental considerations • Genetic factors • Varying responses to specific agents Cultural Assessment • • • • • Health beliefs and practices Past uses of medicine Folk remedies Home remedies Use of nonprescription drugs and herbal remedies • OTC treatments Cultural Assessment (cont'd) • • • • Usual response to treatment Responsiveness to medical treatment Religious practices and beliefs Dietary habits Flash Question: Which of the following statements best reflects the nurse’s understanding of cultural influences on drug therapy and other health practices? A.Some cultures believe cold drinks are unhealthy for the sick person and should be avoided B.Regardless of one’s cultural background, it is crucial to always adhere to recommended medical practices C.Most cultures are fairly standard in reference to the use of medications during illness D.Dietary habits and practices can be of little value to the care of an ill adult Rationale: • A: Some cultures, such as the Chinese, believe cold drinks are unhealthy for the sick person and should therefore be avoided. The End • Good luck with your travels through Pharmacology