Download Document

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