Transcript Drug Therapy in Pediatric Patients

Review of Terms
■Pharmacokinetics: … definition of each?
—Absorption
—Distribution
—Metabolism
—Excretion
■ Pharmacokinetic processes
■ Determine the concentration of a drug at its site(s)
of action.
■ The concentration of drug at its sites of action
determines the intensity and duration of the
response.
—
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Review of Terms
■ Molecule characteristics that allow molecules to
cross membranes more readily
■ Small, uncharged, lipid-soluble, non-protein
bound
■ These characteristics influence how readily a drug
crosses membranes and can be transferred into
specific compartments
■ such as crossing into the placenta, entering the fetus
■ or crossing the blood-brain barrier (BBB) and
entering the CNS
■ Or crossing into breastmilk and being ingested by
baby
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Drug Therapy during
Pregnancy and Breast-Feeding
Drug Therapy during
Pregnancy and Breast-Feeding
Clinical Goal:
Provide effective treatment for mother while
avoiding harm to fetus and/or nursing infant
Clinical Challenge:
How to provide safe and effective treatment when there
is limited data on drug use during pregnancy and
breast-feeding?
Clinical Rule;
Avoid unnecessary drugs during pg/BF, but all drug
therapy cannot and should not be avoided
Limited research data on drugs
during pregnancy and breast-feeding
• Women of reproductive age, infants and children were
historically excluded from drug research trials in order
to protect them from harm.
• This resulted in decades of data-gathering on other
populations (men) that then had to be “translated” or
“extrapolated” to women/children with unique
physiologic considerations.
• In the 1990’s, FDA issued a series of guidelines
mandating participation of women (and minorities) in
new drug trials.FDA can now mandate that drug
companies conduct research trials that include
children.
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• Patient registries- AHU p 78
Medication use during pregnancy is common
• Meds may be used to treat/manage
– Pregnancy-related conditions or complications
– Chronic disorders
– New diagnoses that arise: eg infections (UTI, STI); cancer;
exacerbations/flares of certain conditions
– Much too commonly, drugs of abuse continue to be used
during pg, although many drug-using women choose not to
breastfeed.
• Certain chronic conditions may be (are) far more
dangerous to the fetus than the drug(s) used to control the
chronic condition
• Conditions that threaten the mother’s health may well
impact the fetus/baby as well
• Uncontrolled asthma doubles the incidence of stillbirth among
women with asthma who did not take medications to control
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asthma
Certain conditions or factors that might pose
significant risks to the woman and/or fetus.
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Asthma
Advanced maternal age
lifestyle choices
Anemia/ blood disorder
Mother’s personal medical history
Diabetes
Mother’s family history
Epilepsy
Hypertension
infection
pre-existing obesity
underlying mental health
conditions
http://www.cdc.gov/reproductivehealth/maternalinfanthealth/pregcomplications.htm
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http://contemporaryobgyn.modernmedicine.com/contemporary-obgyn/news/sickle-celldisease-pregnancy?page=full
Basic approach to drug therapy during
Pregnancy and Breast-Feeding
● Decide: should mother’s health condition be managed with
medications or not? Risk vs benefit
● Rule: Avoid drug therapy when reasonably appropriate: is
it safe for mom to go without meds?
● Use non-pharmacological measures to promote health
when applicable/ appropriate: nutrition/ fiber/ water, physical
activity, sleep, emotional support, physical assistance, etc
● If drug therapy is indicated, then choose the drug/ regimen with
the least risk of causing harm
● Some conditions may require temporary use of a “lowest risk”
med during pg/BF, then mother can resume use of a different
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med after pg/BF if desired
Physiologic changes during pregnancy
impact pharmacokinetics.
Dose adjustments of maternal medications
may be necessary.
• Blood volume: By the third trimester, blood volume
doubles, thereby reducing the plasma concentration
of drug.
• RBF: By the third trimester, renal blood flow doubles,
thereby more rapidly eliminating renal-excreted drugs.
• Liver: For some drugs, hepatic metabolism increases
(enzyme induction), thereby decreasing amount of drug.
• Bowel: Tone & motility decrease, thereby prolonging
transit time. Increased time in the bowel allows greater
drug absorption and enterohepatic cycling to occur.
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Placental drug transfer
• Essentially, all drugs can cross the placenta, but the
degree to which specific drugs enter the placenta varies
• Factors that determine drug passage into the placenta are
the same factors that determine drug passage across all
other membranes
• Drugs that cross membranes easily will enter the placenta
most readily = Lipid-soluble
• Drugs that do not cross membranes easily enter the
placenta least readily = Ionized, highly polar, proteinbound, or super LARGE molecules do not cross as
readily
• For practical purposes, assume that any drug taken
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during pregnancy will reach the fetus
Drug-related Adverse Effects during pregnancy
1- Pregnant women are subject to the same adverse
effects as non-pregnant women
2- The physiologic state of being pregnant may itself
impose additional issues for mother
– Ex: Body-habitus, nutrient issues, etc
– Ex: heparin can cause osteoporosis. In pregnant
women, heparin may lead to vertebral compression
fractures
3- Potential adverse effects to:
● Reproductive structures (uterus, cervix, placenta)
● Fetus (organogenesis, functional development)
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Potential impact of drugs on
fetal growth and development
• Teratogen = a medicine or other chemical capable of
producing a permanent structural or functional birth
defect, growth impairment, or fetal death
• Teratogenesis = the process by which congenital
malformations are produced in an embryo or fetus
− greatest concern for many
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Causes of birth anomalies
• About 25% - genetic factors
• Less than 1%- drugs
• Significant but unknown %- environmental
chemicals
• Vast majority of birth defects have unidentified
causes
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Effects of teratogens at various
stages of fetal development
** Not all exposures to teratogens result in congenital anomalies. The
specific chemical/ drug to which the fetus is exposed is of prime
importance. However, the amount of chemical/ dose, frequency, duration,
and fetal stage of development, (and other variables) are additional
contributing factors that cumulatively determine degree of impact. Some
teratogens quickly cause damage, whereas others require prolonged
exposure.
Stage of Fetal Development
Effects of
Teratogen Exposure
Preimplantation
conception – week 2
“All or nothing”
Embryonic period
week 3 – week 8
Gross malformations,
anatomic abnormalities
Fetal period
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Effects are usually functional
Teratogenesis and Stage of Development
Preimplantation
Embryonic Period
Fetal Period
Figure 9-1 Effects of teratogens at various stages of development of the fetus. (From Moore KL: The
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Developing Human: Clinically Oriented Embryology, 5th ed. Philadelphia: WB Saunders Company, 1993. With
permission.)
FDA pregnancy risk categories
The FDA established five categories (A, B, C, D, and X) to indicate a drug's
probable risk to the fetus (1979).
A - Controlled studies in women fail to demonstrate a risk to the
fetus in the first trimester, and the possibility of fetal harm
appears remote.
B - Animal studies do not indicate a risk to the fetus and there are
no controlled human studies, or animal studies do show an
adverse effect on the fetus but well-controlled studies in
pregnant women have failed to demonstrate a risk to the fetus.
C - Studies have’ shown that the drug exerts animal teratogenic or
embryocidal effects, but there are no controlled studies in
women, or no studies are available in either animals or women.
D - Positive evidence of human fetal risk exists, but benefits in
certain situations (e.g., life-threatening situations or serious
diseases for which safer drugs cannot be used or are ineffective)
may make use of the drug acceptable despite its risks.
X - Studies in animals or humans have demonstrated fetal abnormalities or there
is evidence of fetal risk based on human experience, or both, and the risk
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dearly outweighs any possible benefit.
* This organizational schema is likely to be replaced by one that provides more detailed information.
Drugs that Should Be Avoided during pregnancy
because of proven or strongly suspected teratogenicity.
Drugs to avoid- aspirin, ibuprofen on frequent
basis
Drugs of choice – acetaminophen, but not too
excessively
Table 9-1 (p 84)
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Drug Therapy During Breast-Feeding
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Drug Therapy During Breast-Feeding
• Nearly all drugs can enter breast milk, but the extent of
drug entry into breast milk varies greatly
– Drugs that readily cross membranes will readily enter breast
milk
• “Fortunately, there are relatively few instances in
which drugs secreted into breast milk have been
found to cause injury to patients”…
• …For the few drugs that are absolutely
contraindicated during lactation, equally effective
and safer medications are usually available”
(Adams, Holland & Urban, 2014, p 79.)
• If drug concentrations are high enough, the baby will
experience a physiologic/pharmacologic effect, raising
the possibility of harm
• Very little systematic research has been collected in the
US
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• Data coming from Europe
Principles of Drug Therapy During Breastfeeding
• Is the drug therapy necessary?
• What is the safest option for the infant?
• If there is the possibility of harm, monitor
infant blood levels of the drug.
• Minimize infant exposure.
– American Academy of Pediatrics
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Strategies to minimize infant exposure to drug
• Postpone pharmacotherapy until the baby is weaned if
possible; use nonpharm strategies when possible.
• Although most maternal medications probably pose no
harm to the breastfeeding infant, their effects have not
been fully studied.
• If drug needs to be used:
– If possible, Mom should take the medication
immediately AFTER feeding the baby… to reduce (if
possible) the amount of drug in the breast milk
– Avoid breast-feeding during peak effect
– Avoid drugs with long half-life (or active metabolites)
– Drugs that are highly protein-bound are preferred
– Use caution if baby is severely ill; a neonate; or preterm.
They may not have adequate drug metabolizing
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enzymes
Drugs Associated with Serious Adverse Effects
During Breast-Feeding
• Insert Table p 80, AHU
• And lehne p 86
• Immune suppressants (
e.g., cyclosporine. methotrexate)
• Amiodarone & antithyroid drugs
• Benzodiazepines, anticonvulsants,
antihistamine – watch for sedation
• Caffeine – high infant exposure = irritability
• All drugs of abuse, controlled substances
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Resources for further Learning: Drugs
• Drugs in Pregnancy and Lactation: A
Reference Guide to Fetal and Neonatal
Risk, 10th edition by Gerald G. Briggs
BPharm, FCCP, and Roger K. Freeman MD
• www.hsl.uw.edu
• Introduction to 9th edition was written by
Sumner J. Yaffe, MD: excellent, profound
eye-opener.
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Resources for further Learning: Herbs
• HERBS TO BE AVOIDED DURING LACTATION
Two popular herbal remedies for nursing mothers fenugreek and comfrey - can pose a health risk to their
infants. Women advised to avoid fenugreek, but comfrey is
much more dangerous and is banned in Canada.
• Nursing mothers should be steered away from most herbs,
but there are some teas. Chicory, peppermint, orange
spice and red bush tea are all fine. Rose hips is an
especially good tea because it has a very high
concentration of vitamin C.
• www.micromedexsolutions.com
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Drug Therapy in
Pediatric
Patients
NURS 310 Winter 2016
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Drug Therapy in Pediatric Patients
•
Infants/children have largely been excluded from drug research
trials since the 1960’s. As a result, inadequate data currently
exists for prescribers to ensure safe dosing for infants/children.
Two thirds of drugs used in pediatrics have never been
tested in pediatric patients
•
•
Best Pharmaceuticals for Children Act (2002)
Pediatric Research Equity Act of 2003
• After these laws were enacted, early studies indicated-
• 20 % of drugs were ineffective for children (even though they
were effective for adults)
• 30 % of drugs caused unanticipated side effects, some of which
were potentially lethal
• 20 % of drugs required dosages different from those that had
been extrapolated from dosages used in adults
•
These laws were permanently reauthorized as part of the
FDA Safety and Innovation Act (FDASIA) of 2012 MPinson_wi_16 26
Pharmacokinetics: Comparison between Infants
and Adults- Clearly, children are not little adults
Figure 10-1: Drug doses adjusted to body weight were administered to infants and
adults, via IV injection (left) or subcut (right). Duration/time above MEC, and peak
drug levels, differed significantly between infants and adults. Therefore, adjusting
dose
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amounts based on body size alone is inadequate to safely medicate neonates and infants.
Drug Therapy in Pediatric Patients
Pediatric patients respond differently to drugs than adults.
Most of these differences are quantitative.
— Neonates/infants are more sensitive to drugs than
adults
 Heightened sensitivity is due mainly to organ
system immaturity
— Neonates/infants are at increased risk for adverse
drug reactions
— Young patients show greater individual variation
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Pharmacokinetics in Neonates and Infants: ABSORPTION
● Absorption
– Oral administration
• Gastric emptying time
– Prolonged and irregular
– Adult function at 6 to 8 months
• Gastric acidity
– Very low 24 hours after birth
– Does not reach adult values until age 2 years
– Low acidity: Absorption of acid-labile drugs is increased
– Intramuscular administration
• During the first few days of life: Slow, Erratic, Delayed absorption as a
result of low blood flow
• During early infancy, absorption of intramuscular drugs more rapid than
in neonates and adults
– Transdermal absorption
•
•
•
•
Stratum corneum of infant’s skin is very thin
Blood flow to skin greater in infants than in older patients
More rapid and complete for infants than for older children and adults
Infants at increased risk of toxicity from topical drugs
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Pharmacokinetics in Neonates and Infants: DISTRIBUTION
● Distribution
– Protein binding
• Binding of drugs to albumin and other plasma proteins is limited
in the infant
• Amount of serum albumin is relatively low
• Consequence? _______________
– Blood-brain barrier
• Not fully developed at birth
• Drugs and other chemicals have relatively easy access to the CNS
• Infants especially sensitive to drugs that affect CNS function
• Dosage should also be reduced for drugs used for actions outside
the CNS if those drugs are capable of producing CNS toxicity as a
side effect
– Endogenous compounds compete with drugs for available binding sites
• Limited drug/protein binding in infants
• Reduced dosage needed
• Adult protein binding capacity by 10 to 12 months of age
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Pharmacokinetics in Neonates and Infants: METABOLISM
• Hepatic metabolism
– The drug-metabolizing capacity of newborns is low
– Neonates are especially sensitive to drugs that are
eliminated primarily by hepatic metabolism
– The liver’s capacity to metabolize many drugs increases
rapidly about 1 month after birth
– The ability to metabolize drugs at the adult level is
reached a few months later
– Complete liver maturation occurs by 1 year of age
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Pharmacokinetics in Neonates and Infants: EXCRETION
• Renal excretion
– Significantly reduced at birth
– Low renal blood flow, low glomerular filtration, and
low active tubular secretion
– Drugs eliminated primarily by renal excretion must be
given in reduced dosage and/or at longer dosing intervals
– Adult levels of renal function achieved by 1 year
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Drug Therapy in Pediatric Patients:
Pharmacokinetics in Neonates and Infants: consequences
• Neonates and infants are more sensitive to drugs
(than adults) primarily due to organ system
immaturity.
• Elevated drug levels = more intense response
• Delayed elimination = prolonged response
• Immaturity of organs puts patient at risk for both of
these responses
• And increases the risk of adverse effects
• Most pharmacokinetic parameters are similar to those
of adults by the age of 1 year
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Rationale & Examples of
Adverse Drug Reactions
• Neonates/infants are vulnerable to unique adverse effects
related to organ immaturity
– Fewer albumin proteins  greater concentrations of free drug
– Elevated free drug levels  more intense response
– Decreased hepatic metabolism  prolonged response
– Decreased renal elimination  prolonged response
– Blood-brain-barrier not well-formed  CNS effects
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Drug Therapy in Pediatric Patients
Pharmacokinetics: Children
Aged 1 Year and Older
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Drug Therapy in Pediatric Patients
Pharmacokinetics in Children Age 1 Year and Older
• By the age of 1 year, most pharmacokinetic
parameters in children are similar to those of adults
• In children age 1 year and older, drug sensitivity is
more like that of adults
• One important difference: rate of metabolism varies.
Children between the ages of 1 and 12 years
metabolize drugs faster than adults.
– Beginning ~ age 1 year, metabolism is markedly
faster than adults until the baby reaches age of 2
years, then a gradual decline…
– Sharp decline at puberty
– May need to increase dosage or decrease interval
between doses accordingly
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Rationale & Examples of
Adverse Drug Reactions
• Examples of age-related adverse drug reactions:
• Growth suppression (caused by glucocorticoids)
• Discoloration of developing teeth (tetracyclines)
• Kernicterus (sulfonamides)
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Drug Therapy in Pediatric Patients
Dose approximation
based on body surface area
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Drug Therapy in Pediatric Patients:
Dosage Determination
• Pediatric doses have been established for a few drugs, but not most
drugs
• Dosing is most commonly based on body surface area (BSA)
– Initial pediatric dosing is, at best, an approximation
• Nurses must be able to determine if a prescribed pediatric dose is
within a safe range
– Compare the patient’s prescribed dose to the recommended safe dose as
found in a reputable drug reference
• After an initial dose, pt must be monitored carefully for possible
adverse effects
• Subsequent doses must be adjusted on the basis of clinical
response/ outcome and plasma drug concentrations
• Dose adjustments are especially important in neonates and younger
infants
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Drug Therapy in Pediatric Patients:
Dosage Determination
Approximate dosage for a child =
Body surface area of the child × adult dose
1.73 m²
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Drug Therapy in Pediatric Patients:
IV hydration rates
IS YOUR PATIENT
GETTING
ADEQUATE
HYDRATION?
?????????????
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Drug Therapy in Pediatric Patients:
Promoting Adherence to a Medication Regimen
• Effective two-way communication, and
individualized patient education, are critical to
promoting adherence to a drug therapy.
• Provide patient education in several ways, and
always in writing as well. Verbal, infomercial, class,
etc.
• Demonstration techniques should be included
when/if appropriate
• “Teach Back”
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Drug Therapy in Pediatric Patients:
Promoting Adherence to a Medication Regimen
Patient/ caregiver/ family need to know:
• Name of medication, and its purpose
• Dosage size and timing (r/t meals, other meds,
time of day, symptom onset, and so forth)
• Administration route and technique
• Special considerations
• Treatment duration
• Drug storage- safety for children in household
• Nature and time course of desired responses
• Nature and time course of adverse effectsteach possible adverse effects, how to respond,
when and how to follow-up with provider,
and when to call 911
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Drug Therapy in Geriatric Patients
Age-related physiologic changes
 Individuals do not “age” uniformly at the same rate
Rate of aging and effects on physiology vary
“Biologic age” may not match “chronologic
age”
 Rate of change dependent on “lifelong health”
 Genetic makeup
 Lifestyle
 Health status
− presence or absence of disease, injury)
 Cardiovascular fitness
Demographics r/t drug use in the aging population:
Disproportionate drug use
• Drug use among adults age 65 years or
older is disproportionately high
•Represent 13% of current US population
•Consumers of 33% of prescription drugs
•Consumers of 40% of OTC drugs
• Ambulatory older adults use 2 to 4
prescription drugs regularly
• Long-term care residents use an average of
7-8 medications (Tindall, Sedrak & Boltri,
2014)
Demographics r/t drug use in the aging
population:
polypharmacy
&
associated
risks
Greater prevalence in older adults due to
increased prevalence and/or severity of disease
Drugs to manage disease(s)
Drugs to manage symptoms (of disease or aging)
Drugs to treat side effects of other drugs
Multiple prescribers, excessive prescribing
Multiple pharmacies
Drug advertising (…pills to cure all…stay young..)
Older adult patients experience more adverse
drug reactions and drug-drug interactions than
younger patients do
Age-related physiologic changes
pose unique considerations to
geriatrics
Age-related changes COMBINE with diseaserelated changes to impact pharmacokinetics
and pharmacodynamics
Most commonly, effects of drugs are increased
in older adults
Older adults are “more sensitive” to drugs
than younger adults
However, effects of some drugs may be
decreased
(eg beta blockers)
Older adults show wider individual variation in
responses
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Age-related physiologic changes
Age and/or disease- related physiologic changes
• profoundly affect pharmacokinetics
• whereas pharmacodynamic effects not understood
• Which pharmacokinetic change is responsible for most
ADRs in older adults? → Reduced renal excretion
•
Age-related Physiologic changes: gastrointestinal
changes affect pharmacokinetics r/t absorption
Age-related changes to GI tract
 Reduced GI blood flow
 Reduced motility
 Atrophy of mucosa and glands
Reduces digestive secretions
Decrease in number of absorptive cells; decreased
absorptive surface area
gastric acid production may be unchanged or
reduced
(ie increased pH)
delayed gastric emptying
Effect on pharmacokinetics
 The rate of absorption may slow with age, but overall
percentage (amount) absorbed from an oral med
does not change with age
Age-related Physiologic changes: body composition
changes affect pharmacokinetics r/t distribution
Body composition/ other changes & volume of distribution
 Decreased percentage of lean body mass
 Increased percentage of body fat
Storage depot for lipid-soluble drugs
Increased half-life of fat-soluble drugs
 Decreased total body water
Increases serum concentration of water soluble drugs;
effects more intense
 Reduced concentration of plasma proteins (especially
serum albumin)
Reduced protein binding of drugs and increased
levels of free drug
In some people, albumin levels and “physiologic
reserve” may be significantly reduced and depleted
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Age-related Physiologic changes: hepatic changes
affect pharmacokinetics r/t hepatic metabolism
Age-related changes to liver
—reduced hepatic blood flow
—reduced liver mass
—decreased activity of some hepatic enzymes occurs
 Hepatic metabolism declines with age
 Age – related changes combine with effects of
concomitant disease or social impacts such as
decreased nutritional status
Half-lives of some drugs may increase, responses may b
prolonged
Responses to some oral drugs may be enhanced
(eg drugs that undergo extensive first-pass effect)
Age-related Physiologic changes: renal changes
affect pharmacokinetics r/t renal excretion
Age-related changes to kidney:
 Renal function undergoes progressive decline
beginning in early adulthood:
Reduction in number of functional nephrons,
Decreased glomerular filtration rate,
Decreased active tubular secretion;
Diminished ability to adapt to changes in electrolyte,
acid levels
 Reduction in renal blood flow, decreased renal
excretion
 Drug accumulation as a result of reduced renal
excretion is the most important cause of adverse drug
reactions, drug-drug interactions, and may lead to
toxicity in older adults
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Age-related Physiologic changes:
Assessment of Renal Function
Renal function should be assessed for all pts
taking drugs that are eliminated primarily by
the kidneys
In older adults:
Use creatinine clearance to assess renal
function
(rather than serum creatinine), because
lean muscle mass (source of creatinine)
declines in parallel with kidney function
Creatinine levels may be normal even
though kidney function is greatly reduced
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Age-related Physiologic changes:
Assessment of Renal Function, cont’d
• Cockcroft – Gault Equation is adequate for most
adult patients with normal muscle mass and serum
creatinine (Scr) < 4.5 mg/dL
Creatinine
=
clearance
(ml/min)
_140 - age in yrs
x weight in kg _
72 x serum creatinine (% mg/100mL
(for women, multiply result by .85)
Age-related Physiologic changes:
Assessment of Renal Function: example of
Cockcroft– Gault Equation
80 year old male weighs 72
40 year old male
kg
weighs 72 kg
Yearskg
cr cl =
(140 - 40) 72
72 (1.0)
(140 - 80) 72
cr cl = 72 (1.0)
Serum
Creatinine
cr cl = 100 ml/min
cr cl = 60 ml/min
* To estimate cr cl in women, multiply result by .85
Age-related physiologic changes
impact pharmacodynamics
Alterations in receptor properties may underlie
altered sensitivity to some drugs. Examples:
Some drugs have more intense effects in older
adults
Warfarin and certain central nervous system
depressants
→ possibly due to increases in number of
receptors, affinity or both
Beta blockers are less effective in older adults,
even in the same concentrations
→ possible reduction in number of beta
receptors , affinity of beta receptors for
beta-receptor blocking agents, or both
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Adverse drug reactions and drug-drug interactions are HIGH
in older adult population: Predisposing Factors that increase
rate of ADR
Drug accumulation secondary to reduced renal
function is the most important cause of adverse
drug reactions and drug-drug interactions in older
adults
Polypharmacy
Greater severity of illness
Multiple pathologies
Greater use of drugs that have a low
therapeutic index (for example, digoxin)
Increased individual variations secondary to
altered pharmacokinetics
Inadequate supervision of long-term therapy
Poor patient adherence
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Drug Therapy in Geriatric Patients:
Examples of ADE/ ADR
May be undetected in older adults because they
can mimic characteristics of problems, disease,
or symptoms commonly present in the elderly
Symptoms of ADR in older adults are often
nonspecific
Examples:
−Oversedation
−Cognitive changes such as confusion
−Dizziness
−Hallucinations
−Accidents/ Falls
−Bleeding
−and other unwanted, uncomfortable, or
dangerous effects
How can the nurse decrease incidence of
adverse drug reactions and drug-drug interactions
based on altered pharmacoKINETICS?
 Identify the organs involved
 Monitor organ functioning
Liver-
PT/INR good indicators of hepatic function
AST, ALT are markers for hepatic inflammation
Ammonia
albumin
Kidneys – creatinine clearance
 Assess for symptoms that suggest a decline in organ
function
 Assess for desired and adverse responses to the drug
How can the nurse decrease the incidence of
adverse drug reactions and drug-drug interactions
based on altered pharmacodynamics?
 Differences in receptor number and binding =
UNPREDICTABLE
 Assess for desired and adverse responses to the drug
 Use caution with drugs that can have serious adverse
effects, especially with low therapeutic index drugs
 Use less toxic analgesics first (e.g., acetaminophen versus
NSAID)
 Watch for delayed signs of drug-related toxicity
 Start with low doses of meds… titrate up as needed
 at appropriately spaced time intervals, carefully monitoring for
effect
 Remember: it takes between 4 – 5 doses of meds
administered at properly spaced/timed intervals (r/t half-lif
to achieve plateau
Start low . . . . Go slow!