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Flashcards in Module 1-2 Deck (12):
1

Pregnancy

First trimester is the period of greatest danger
for drug-induced developmental defects
 Drugs cross the placenta by diffusion
 During the last trimester the greatest
percentage of maternally absorbed drug gets to the fetus
FDA pregnancy safety categories

2

Pregnancy Safety Categories

Category A: No risk to human fetus
B: No risk to animal fetus, humans unknown
C: Adverse affects in animal fetus, humans unknown
D: Possible fetal risk in humans, benefit vs. risk may warrant use
X: Fetal abnormalities reported, evidence of fetal risk. Should NOT be used by pregnant women

3

Neonatal and Pediatric
Considerations:
Pharmacokinetics

Absorption
 Gastric pH less acidic
 Gastric emptying is slowed
 Intramuscular absorption faster and irregular

4

Neonatal and Pediatric
Considerations: Pharmacokinetics
(cont’d)

Distribution
 The younger the person, the greater the % of total body water
 Greater TBW means fat content is lower
 Decreased level of protein binding
 Immature blood-brain barrier—more drugs enter the brain

5

Neonatal and Pediatric
Considerations: Pharmacokinetics
(cont’d)

Metabolism
Liver immature, does not produce enough
microsomal enzymes
Older children may have increased metabolism, requiring higher doses than infants

6

Neonatal and Pediatric
Considerations: Pharmacokinetics
(cont’d)

Excretion
 Kidney immaturity affects glomerular filtration rate
and tubular secretion
 Decreased perfusion rate of the kidneys may reduce excretion of drugs

7

Factors Affecting Pediatric Drug
Dosages

Skin is thin and permeable
 Stomach lacks acid to kill bacteria
Lungs have weaker mucus barriers
Body temperatures less well regulated and
dehydration occurs easily
Liver and kidneys are immature, impairing drug metabolism and excretion

8

Dosage Calculation for
Pediatric Patients

Body surface area method
 Using the West nomogram
 Body weight dosage calculations
 Using mg/kg

9

The Elderly:
Pharmacokinetics

Absorption
 Gastric pH less acidic
 Gastric emptying slowed
 Movement through GI tract slowed
 Blood flow to GI tract reduced
 Use of laxatives may accelerate GI motility

10

The Elderly:
Pharmacokinetics (cont’d)

Distribution
 Lower total body water percentages
Increased fat content
 Decreased production of proteins by the liver, resulting in decreased protein binding of drugs (and increased circulation of free drugs)

11

The Elderly:
Pharmacokinetics (cont’d)

Metabolism
Aging liver produces fewer microsomal enzymes, affecting drug metabolism
 Reduced blood flow to the liver

12

The Elderly:
Pharmacokinetics (cont’d)

Excretion
 Decreased glomerular filtration rate
Decreased number of intact nephrons