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Fall'20 Pharmacology III COPY > Peds & Geri > Flashcards

Flashcards in Peds & Geri Deck (151)
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1
Q

Young children are not simply small adults; they have unique physiology that changes remarkably with age; especially in what?

A

The first year

2
Q

Neonates and infants have a high percentage of body water. This means what?

A

Drugs distributed in water have a high volume of distribution

3
Q

In infants, cardiac output is dependent on:

A

Heart rate!

4
Q

Due to infants/neonates having a high body water percentage what may be enhanced for this population?

A

Drug toxicity

5
Q

Anesthetic drugs that cause a reduction in heart rate may ________ depress blood pressure and blood flow to tissues.

A

Disproportionately

6
Q

Name the three common age groups of the pediatric population:

A
  1. ) Neonates - less than 4weeks after birth
  2. ) Infants - between 4 wks and 1 yr
  3. ) children - greater than 1 yr of age
7
Q

Neonates often have two subdivisions. What are they?

A
  1. Prematurely (before 37 wks gestation)

2. Term (greater than or equal to 37 weeks)

8
Q

The understanding, assessment and management of acute pain in pediatrics has lagged behind that of adults. Pediatric pts often receive….

A

Less analgesia postoperatively than adults

9
Q

What was the established view of neonates regarding pain?

A

Neonates were neither capable of perceiving pain NOR able to remember painful stimuli

10
Q

The primary indication for anesthesia once was the prevention of…

A

Movement during surgery! :(

Achieved with little more than Controlled ventilation and NMB’s

11
Q

The behavioral response to standard noxious stimulus in the neonate may be:

A

Unpredictable

12
Q

The stress response associated with noxious stimuli in the neonate is:

A

Impressive and CONSISTENT

13
Q

Infants undergoing surgery w/o adequate anesthesia suffer significant ________ and ________ response which adversely affects post op recovery.

A

Hormonal and metabolic

14
Q

Important developmental changes in the determinants of pharmacoKINETICS occurs during:

A

Infancy

15
Q

Infantry changes in pharmacokinetics include:

A
  • drug absorption
  • distribution
  • Binding
  • entry into the brain across BBB
  • Metabolism
16
Q

The principal site of absorption for drugs given ORALLY is:

A

The small intestine

17
Q

The rate at which a drug leaves the stomach is the determinant of speed of:

A

Drug Absorption

18
Q

Oral Drug absorption is determined by:

A

The rate at which a drug leaves the stomach

19
Q

The rate at which most drugs are absorbed when given orally is SLOWER in neonates and infants than in older children because:

A

Gastric emptying is delayed

20
Q

Delayed Gastric emptying is more prevalent in what pediatric populations?

A

Neonates and infants (vs older children)

21
Q

In neonates, the time (Tmax) at which maximum concentration (Cmax) is achieved is ______.

A

Prolonged

22
Q

Gastric emptying and intestinal motor motility rates reach normal adult rates at what age?

A

6-8 months

23
Q

In neonates, the gastric pH is:

A

Elevated.

Greater than 4

24
Q

The increased gastric pH in neonates increases the bioavailability of ___________. And decreases the bioavailability of _______ ______ when given orally.

A

Increases: acid-labile compounds (PCN G)
Decreases: weak acids (Phenobarbital)

25
Q

Compared to the older child, The infant gut is more permeable to:

A

Large molecules (proteins, high molecular-weight drugs)

26
Q

Absorption of _______ drugs is increased in neonates due to what 3 reasons?

A

Topically applied drugs (corticosteroids, LA Creams, antiseptics)

Due to:

  1. ) Larger relative skin surface area
  2. ) increased cutaneous perfusion
  3. ) thinner stratum corneum
27
Q

Neonates have a tendency to form methgb b/c they have reduced levels of :

A

Methemoglobin reductase

28
Q

B/c fetal hemoglobin is more readily oxidized than adult hgb, and neonates have a reduced level of methgb reductase what tends to happen?

A

Methemoglobin

29
Q

The reluctance to use EMLA cream in neonates results because of what reasons:

A
  1. ) increased epidermis absorption

2. ) reduced methemoglobin reductase

30
Q

EMLA has been shown to be safe in neonates when applied as a

A

One time dose.

Shown to be efficacious for circumcision pain

31
Q

B/c of neonatal reduced muscle bulk, skeletal muscle blood flow, and muscular contractions, it might be expected that IM absorption would be decreased in neonates.

Why is this not necessarily true?

A

Neonates have high density of skeletal muscle capillaries

32
Q

Compared to adults, Pulmonary absorption ion infants and children is generally :

A

More rapid

33
Q

A more rapid “wash in” of inhalational Anesthetics in neonates and infants is caused by what 2 factors:

A
  1. Greater fraction of CO going to vessel rich tissue group (LUNGS)
  2. Lower tissue/blood solubility of inhaled Anesthetics
34
Q

When delivered at a constant rate, an inhalation drug with a greater volume of distribution will take longer to reach:

A

Steady state concentration

35
Q

What ratio is achieved more rapidly in infants than in adults?

A

Fe / Fi Ratio (equilibration)

36
Q

Because the Fe/Fi ratio (equilibration) is achieved more rapidity in infants, the increase of what may occur quickly?

A

toxicity of inhaled anesthetics

Bradycardia, cardiac depression d/t halothane

37
Q

Why do you not want bradycardia in infants/neonates?

A

CO is dependent on HR1

38
Q

Age has little effect on the solubility of the less soluble drugs, N2O, and Sevo.

True or False?

A

True

39
Q

In neonates, induction of anesthesia will be

A

Slowed

40
Q

Right to left shunting of blood in the neonate will do what to the rate of induction?

A

Speed up.

41
Q

Right to left shunting may be caused by: (what was in ppt)

A

Pulm Atresia
Hypoplastic left heart syndrome

Intrapulmonary condition: atelectasis, Congenital vascular malformations

42
Q

Total body water = in the preterm neonate

A

85%

43
Q

Total body water.= in the term neonate

A

75%

44
Q

Total body water decreases at about 5 months and remains relatively constant afterwards at approximately this %:

A

60%

45
Q

At birth ECF = %?

At 1 yr ECF = %?

A

45% at birth

26% at 1 yr

46
Q

ECF continues to reduce during childhood until the normal adult level is reached.

Adult ECF % is?

A

18%

47
Q

Examples of polar drugs:

A

Aminoglycosides

NMBDs

48
Q

Polar drugs distribute _______ into the ECF but enter cells more ______.

A

Rapidly into ECF

Enter cells more slowly

49
Q

Initial dose fo polar drugs is usually higher or lower in the neonate/infant compared to older children?

A

Higher

50
Q

Why is initial dosing of polar drugs (NMBDs, AMG’s) higher in neonate/infant vs children and adults?

A

Larger ECF volume

51
Q

Approx Intubation doses of Succinylcholine in infant, Children, and adolescent/adults:

A

Infant: 3-4mg/kg
child: 2mg/kg
Adolescent/adult: 1mg/kg

52
Q

What is the percentage of body wt /fat in a 1.5kg premie vs term neonate?

A

3% in 1.5 kg premie
12% in term

This proportion doubles by 4-5months of age

53
Q

Baby fat is lost when infants start walking and protein mass increases by 20% in a term neonate

What % in adult?

A

50%

54
Q

Acidic drugs tend to bind to

A

Mainly to albumin

55
Q

Basic drugs bind to

A

Globulins
Lipoproteins
Glycoproteins

56
Q

Examples of acidic drugs:

A

Barbiturates

57
Q

Example of basic drugs:

A

Diazepam

Amide LA’s

58
Q

In the newborn, relative to adults, plasma protein binding of many drugs is:

A

Decreased

59
Q

Reduced protein binding in neonates is important for drugs with more :

A
  • more than 95% pr-binding
  • high extraction ratio
  • narrow therapeutic index (lidocaine)
60
Q

Binding to albumin is increased in neonates vs infants/children/adults.

True or false?

A

False.

Albumin binding is reduced in neonates

61
Q

Plasma albumin concentrations are lowest in

A

Premature infants

And other fetal proteins such as x-fetoprotein, have a reduced affinity for drugs.

62
Q

In neonates, what is competing with acidic drugs for albumin binding sites?

A

Increased concentrations of free fatty acids and unconjugated bilirubin

63
Q

Alteration in neonate ionization and binding properties of plasma proteins due to the neonatal (metabolic) tendency:

A

To manifest a metabolic acidosis

64
Q

Approx what age are serum albumin concentrations about that of an adult?

A

5 months

*binding capacity approaches adult values by 1 yr of age

65
Q

Most drugs cross physiologic membranes as a result of

A

Passive diffusion

ionization

66
Q

Maturational changes in tissue binding also affect drug:

A

Distribution

67
Q

Tissue binding also increases the

A

Volume of distribution

68
Q

Myocardial digoxin concentrations in infants:adults is ?

A

6 times higher in infants than adults

Despite similar serum concentrations

69
Q

Name several factors that influence the process of tissue and protein binding:

A
  • molecular size
  • ionization
  • tissue binding
  • lipophilicity
  • P-glycoprotein (member of ATP transporter family is capable of producing a biological barrier to membrane passage
70
Q

Maturational changes in tissue binding also affect drug

A

Distribution

71
Q

Tissue binding increases the

A

Volume of distribution

72
Q

How do Myocardial digoxin concentrations in infants compare to those in adults? (Similar serum concentrations)

A

Infants are 6 times HIGHER than adults

73
Q

What is a lipid membrane interface b/w the endothelial cells of the brain blood vessels and the ECF of the brain?

A

The BBB

74
Q

Brain uptake of drugs is dependent on what two elements?

A
  1. Lipid solubility
  2. Blood flow

Example: uptake is enhanced by high lipid solubility and cerebral blood flow.

75
Q

it’s postulated that the BBB permeability to water soluble drugs (like morphine) changes with

A

Maturation

76
Q

Fentanyl is water or lipid soluble?

A

Lipid

77
Q

How does fentanyl effect the respiratory depression of infants in comparison to adults (with comparable plasma concentrations)?

A

It is similar in infants and adults

78
Q

The increased neonatal respiratory depression observed in morphine could be due to ________ rather than ____ age related changes.

A
  • pharmacoKINETICS

- BBB

79
Q

In term neonates, how is the vol of distribution and plasma concentrations of morphine impacted?

A

Term neonates vol distribution = reduced

Initial plasma concentrations = may be higher in neonates than adults

80
Q

Respiratory depression is the same in children from what ages at the same morphine plasma concentration?

A

2-570 days (about 1.5 yrs old)

81
Q

The majority of drug metabolism (clearance) occurs in the

A

Liver

82
Q

Majority of drug metabolism (clearance) occurs in the liver where lipid soluble compounds are converted to more

A

Water soluble compounds

83
Q

Water soluble compounds are generally excreted in the

A

Bile or urine

84
Q

Water soluble drugs may be excreted unchanged in the kidneys by these two functions:

A
  1. Glomerular filtration
    And/or
  2. Renal tubular secretions
85
Q

Many renal and liver processes are immature int he neonate and mature within the first year of life. During this time, what systems appear to evolve and approximate adult rates?

A

Enzyme systems

86
Q

Drugs are metabolized in the live by

A

Phase I and II reactions

87
Q

Phase 1 metabolic processes involve what?

Commonly catalyzed by the….

A

Oxidative, reductive, or hydrologic reactions.

  • catalyzed by the mixed function oxidase system
88
Q

Phase II pathways involve

A

Conjugation

89
Q

What phase reactions are generally lost in the elderly?

A

Phase II (conjugation)

90
Q

The major enzyme system for oxidation of drugs is:

A

Cytochrome P450 (CYP)

91
Q

When does CYP appear to be “switched on”?

A

At birth

92
Q

CYP2E1 activity does what after birth?

A

Increases

93
Q

CYP2D6 becomes detectable when?

A

After CYP2E1 activity which increases after birth

94
Q

CYP3A4 and CYP2C family of enzymes appear at what age?

A

During the first week

95
Q

The last CYP enzyme to appear is?

A

CYP1A2

96
Q

Name the CYP enzymes in order (5);

A
  1. CYP2E1 (increases after birth)
  2. CYP2D6 (detectable soon after)
  3. CYP3A4 and
  4. CYP2C family appear during first week
  5. CYP1A2 (last to appear)

EDAC-1A
“Eliminate drugs and call 1A”

97
Q

Immaturity of the CYP systems in neonates may have important effects on the risk of

A

Drug toxicity

98
Q

neonates are dependent on what CYP systems for levobupivacaine and ropivacaine clearance?

A

Levobupivacaine = CYP3A4

Ropivacaine = CYP1A2

99
Q

What factor(s) dictate the reduced epidural infusion rates in neonates?

A

The dependence on immature CYP systems — CYP3A4 for levobupivacaine and CYP1A2 for ropivacaine clearance

100
Q

What is the toxic metabolite of paracetamol (acetaminophen)?

A

N-acetyl-p-benzoquinone imine (NAPQI)

101
Q

n-acetyl-p-benzoquinone imine (NAPQI) is formed by

A

CYP2E1, 1A2, and 3A4

102
Q

NAPQI metabolite binds to intracellular hepatic macromolecules to produce cell….

A

Necrosis and death

kill the liver…. slow death

103
Q

Fentanyl is metabolized by ______ into _____.

A

Fentanyl is metabolized by oxidative N-dealklation (CYP3A4)

Into; NORfentanyl

104
Q

NORfentanyl is then….

A

Hydroxylated

105
Q

All metabolites of fentanyl are in/active?

A

INACTIVE

106
Q

Fentanyl clearance in term neonates is what percentage of adult values?

When is clearance that of an adult?

A

70-80% of adult values

Reaches adult values within the first TWO weeks of life.

107
Q

Where is most of fentanyl metabolized?

A

Liver.

Small amt by kidney

108
Q

High dose therapy with fentanyl results in prolonged effects in the neonate d/t reduced clearance.

When intraabdominal pressures are increased, how is clearance effected?

A

Fentanyl clearance is reduced.

Increase IAP (omphalocele) decreases hepatic BF and decreases hepatic extraction

109
Q

What two processes are drugs and their metabolites excreted by the kidneys :

A
  1. Glomerular filtration

2. Tubular secretion

110
Q

GFR is approx %? Of adults at birth in a term neonate?

At 1 year?

A

GFR is about 30% of adult at birth

~ 90% at 1 year

111
Q

What pathway is responsible for the elimination of PCN?

A

Para-amino hippurate pathway

112
Q

Para-amino hippurate pathway, immature in neonates, results in an increased _________ for PCN and related compounds.

A

Elimination half life

113
Q

Why is the elimination half life of PCN and related compounds increased in neonates?

A

Immature para-amino hippurate pathway

114
Q

At birth, slightly acidic urine results in:

A

Decreased elimination of weak acids

115
Q

What is the approx pH of urine at birth?

A

6-6.5

116
Q

The immaturity of renal clearance pathways for caffeine results in prolonged effect of what prodrug used to treat/prevent post-op apnea in preterm neonates?

A

Theophylline

117
Q

N-methylation of theophylline produces what?

A

Caffeine

118
Q

oxidative demehtylation by CYP1A2 is responsible for the metabolism of _____.

A

Caffeine

119
Q

In neonates, caffeine metabolism is

A

Deficient

120
Q

Theophylline is effective for post-op apnea in premies b/c of what reason?

A

Caffeine is cleared slowly by the immature kidneys

121
Q

Remifentanil, and to a lesser extent, atracurium are rapidly broken down by

A

Nonspecific esterases (in tissue and erythrocytes)

122
Q

Remifentanil clearance in all age groups is approx ?

A

150 L / Hr (70kg)

123
Q

Clearance is greater in what pt population?

A

Term neonates than infants/adults

124
Q

Clearance is expressed

A

Per kilogram of body weight

125
Q

The constant rate of hydrolysis by plasma esterase of propacetamol to paracetamol is age or size related?

A

SIZE related

Not age related

126
Q

Ester LA’s are metabolized by

A

Plasma pseudocholinesterase

127
Q

Plasma pseudocholinesterase concentrations are greater or less in neonates?

A

Less/reduced

128
Q

Opioid receptors are not fully developed in

A

Newborn rats

And mature into adulthood

129
Q

Neonatal sensitivity to morphine is attributed to ….

A

PharacoKINETIC rather than pharmacoDYNAMIC differences

130
Q

Neonates have an increased sensitivity to the effects of what drug class?

Why?

A

NMBD’s

Reason is unknown, observation that there is a threefold reduction int he release of ACh from infant (rat) phrenic nerve

131
Q

The NT at most inhibitory synapses in the human CNS

A

GABA

132
Q

GABAa Receptor is the site of action for:

A
  1. Benzodiazepines
  2. Barbiturates
  3. Numerous anesthetic drugs
133
Q

At birth, the cerebellum contains 1/3 the number of GABAa receptors found in the adult. These receptors also have reduced binding affinity for

A

Benzodiazepines

134
Q

GABAa Receptor complex becomes more prevalent from birth to ____.

The values then decrease to ___% of peak values by ___ yrs.

A

Birth to 2 yrs.

Decrease to 50% of peak values by 17 years

135
Q

GABA receptor complex changes are consistent with age related MAC changes of inhalational anesthetics and possible contribute to why we …

A

Give higher doses of Midazolam are required in young children for sedation

136
Q

The amount of drug going to the brain (and subsequent anesthetic effect) may also be affected by changes in

A

Regional blood flow

137
Q

Bronchodilators have a REDUCED effect in infants b/c of

A

Immaturity of bronchial smooth muscle in at this age

138
Q

Cardiac calcium stores in the endoplasmic reticuluma re reduced in the neonatal heart b/c of

A

Immaturity

139
Q

Exogenous calcium has greater impact on contractility in neonates than in

A

Older children or adults

140
Q

The development and discovery of new drugs based on genome information is called

A

Pharmacogenomics

141
Q

Pharamacogenetics may influence either

A

Pharmacokinetics OR pharmacodynamics

142
Q

Pharmacogenetics is the genetically determined variability in

A

Drug metabolism

143
Q

A well known example of genetic variability influence is:

A

Plasma cholinesterase activity and succinylcholine metabolism

144
Q

Polymorphism of CYP2D6 is inherited as an autosomal recessive trait.

HomoZygous individuals are deficient int eh metabolism of what groups of drugs:

A
  • Antidepressants
  • Beta adrenoceptor blocking drugs
  • Neuroleptic drugs
  • Opioids
145
Q

The growth in body weight and length and changes in physiology during infancy and childhood impact drug:

A
  • absorption
  • distribution
  • metabolism
146
Q

Neonatal - concomitant changes affect protein binding and receptor physiology and alter the ______ of drugs

A

Efficacy

147
Q

What year of life is the most critical period during which the majority of these maturational changes take place?

A

The first year

148
Q

In neonates and young infants, Orally administered drugs are often absorbed more ….

Due to?

A

Slowly

Due to delayed gastric emptying

149
Q

What element of neonates affects the bioavailability of orally administer acid-labeled compounds and weak acids?

A

Higher gastric pH 6-6.5

150
Q

Inhalational anesthetics are generally absorbed more rapidly in infants and children than in adults; however, induction of anesthesia is slower in the presence of

A

Right to left shunting of blood

From cyanosis CHD or intrapulmonary conditions

151
Q

Processes involved in metabolism and clearance of drugs mature during

A

The first year of life?