Pharmacokinetics and Pharmacodynamics in Aging

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Questions and Answers

What is the approximate rate at which first-pass metabolism decreases in older adults after the age of 40?

2% per year

0.1% per year

1% per year (correct)

0.5% per year

Which of the following pharmacokinetic changes is most likely to necessitate an adjustment in medication dosage for an elderly patient?

Decreased sensitivity to anticholinergic effects

Increased Phase I metabolism

Enhanced renal clearance

Dynamic changes in renal function (correct)

Besides changes in drug-receptor interaction, what other factors may contribute to pharmacodynamic differences observed in older adults, particularly the frail?

Reduced anticholinergic sensitivity

Enhanced first-pass metabolism

Increased homeostatic responses

Pathologic organ changes (correct)

What specific adverse effects of certain drugs are older adults, specifically those with cognitive impairment, considered most vulnerable to?

Central nervous system (CNS) adverse effects Signup and view all the answers

When presented with an unlabeled blister pack of medications from an elderly patient, what is the most immediate and practical step a healthcare provider should consider, according the text?

The text does not specify an action to take. Signup and view all the answers

During pregnancy, how does the alteration in gastrointestinal (GI) physiology most significantly influence drug absorption?

Increased gastric pH can alter the ionization of drugs, affecting absorption. Signup and view all the answers

What is the primary effect of the increased plasma volume during pregnancy on the pharmacokinetics of a drug?

It results in a decrease in the blood concentration of some drugs. Signup and view all the answers

How does the increased body fat during pregnancy affect the distribution of lipophilic drugs?

It acts as a larger reservoir, extending the duration of action for lipophilic drugs. Signup and view all the answers

How does the change in protein binding during pregnancy alter the efficacy of highly protein-bound drugs?

It increases the concentration of free drug, potentially leading to an exaggerated effect. Signup and view all the answers

What effect do pregnancy hormones primarily have on metabolic enzyme activity?

They can either induce or inhibit metabolic enzymes, leading to variable drug effects. Signup and view all the answers

How does the increased blood flow to the kidneys influence drug elimination during pregnancy?

It leads to faster drug elimination, potentially reducing drug effectiveness. Signup and view all the answers

What is the consequence of reduced hepatobiliary drug clearance during pregnancy on drug pharmacokinetics?

It can increase the drug half-life due to slowed clearance. Signup and view all the answers

Why does renal clearance of drugs become difficult to predict during pregnancy based on the content provided?

Because the interplay of increased blood flow, filtration, and reabsorption provides complex changes. Signup and view all the answers

Which of the following changes in drug pharmacokinetics is most likely to be seen in elderly patients due to age?

Reduced lean body mass Signup and view all the answers

What is a primary concern when administering intravenous medication to a pediatric patient?

Administering high concentrations and large total fluid volumes Signup and view all the answers

Which route of drug administration is most likely to have unpredictable absorption in pediatric patients?

Rectal Signup and view all the answers

Which of the following factors most significantly affects the ability of elderly patients to adhere to their drug regimens?

Limited financial resources and mobility difficulties Signup and view all the answers

What is a typical gauge for a needle used for subcutaneous injections in pediatric patients?

27 or 23 gauge Signup and view all the answers

Which of the following is NOT a typical consideration in the administration of medications to geriatric patients?

Age-related increase in lean body mass Signup and view all the answers

Compared to adults, a neonate's total body water content results in what effect on the distribution of water-soluble drugs?

Increased distribution due to greater total body water. Signup and view all the answers

When administering medications to infants, which of the following would be most important?

Considerations of the total fluid volumes administered in IV medications Signup and view all the answers

How does the permeability of an infant's blood-brain barrier compared to that of adults affect drug distribution?

It is more permeable, increasing drug access to the brain. Signup and view all the answers

Which of the following most accurately describes the change in drug absorption in elderly patients?

Changes in drug absorption tend to be clinically inconsequential for most drugs. Signup and view all the answers

A neonate's gastric pH differs from that of of an adult. How does the higher pH in a neonate affect drug absorption?

It will slow down intestinal absorption. Signup and view all the answers

What is a typical age-related change in body composition that affects drug distribution in geriatric patients?

Increased fat percentage and reduced lean body mass Signup and view all the answers

How does the stratum corneum of an infant's skin affect drug absorption?

Increased absorption due to a thinner stratum corneum. Signup and view all the answers

According to the material presented, what is a suggested method for oral medication administration in pediatric patients?

Using a needle-less syringe Signup and view all the answers

What factor contributes most significantly to the variability of intramuscular drug absorption rates in infants?

Increased capillary network. Signup and view all the answers

How do the differences in respiratory physiology affect the absorption of inhaled drugs in infants, compared to adults?

Increased absorption of gases but decreased absorption of aerosols. Signup and view all the answers

Which of the following best describes how phase I metabolism activity changes from birth to late puberty?

Reduced at birth, increases during first 6 months, exceeds adult rate in few years, slows down at adolescence, and attains adult rates at late puberty. Signup and view all the answers

What is the major route of elimination for drug metabolites in pediatric populations?

Bile or kidneys. Signup and view all the answers

How does the glomerular filtration rate (GFR) in an infant compare to that of an adult, and how does this impact drug elimination?

Decreased GFR, leading to reduced elimination. Signup and view all the answers

Which of the following best describes the half-lives of drugs like phenytoin, barbiturates, and analgesics in neonates compared to adults?

2 to 3 times longer in neonates. Signup and view all the answers

Which drug characteristic is LEAST likely to increase placental drug transfer?

Extensive protein binding Signup and view all the answers

What percentage range of umbilical venous blood flow typically undergoes first-pass metabolism in the fetal liver?

40-60% Signup and view all the answers

The FDA removed the pregnancy categories (A, B, C, D, and X) from drug labeling primarily because:

They caused confusion and difficulty applying available information to clinical decisions. Signup and view all the answers

According to the new FDA labeling requirements, what information must be included for drugs under the section related to reproductive potential?

Risk summary, clinical considerations, and available drug data for pregnancy, lactation, and reproductive potential Signup and view all the answers

What impact would an increase in sensitivity to anesthetic drugs during pregnancy have on therapeutic indices?

The therapeutic index would decrease Signup and view all the answers

If a drug is metabolized by the placenta, what effect would this placental metabolism have on the drug's concentration reaching the fetus, compared to a drug not metabolized by the placenta?

The drug concentration would be lower in the fetus due to first pass metabolism in the placenta Signup and view all the answers

A woman is planning to conceive, and her doctor is reviewing her current medication. Which aspect of the drug's properties would be of greatest importance when deciding if use should be continued?

The drug's potential to cross the placenta and its effect on the fetus. Signup and view all the answers

Which factor is MOST important when choosing a drug for a woman in labor?

The drug's potential impact on both the mother and the fetus. Signup and view all the answers

Comparing drug choices during pregnancy with a non-pregnant setting, when would you expect drug doses to be most affected by physiological changes?

In the third trimester due to increased sensitivity to drugs and altered physiology Signup and view all the answers

If a drug is described as having a `high` degree of protein binding, what effect will this have on its placental transfer?

Decrease placental transfer due to less free drug available to cross Signup and view all the answers

Study Notes

Special Populations

Topics include obstetrics, pediatrics, and geriatrics.

Requirements

Review the "Special Populations" presentation on Brightspace.
Read these articles: Medication and the elderly, Drug-related illness in the elderly, Drug categories of concern in the elderly, Changes in Drug Response in Pregnancy, Changes in Drug Response in Neonates and Infants.
Watch these videos: Elderly and their medication (3:03)

Objectives

Describe how pregnancy affects pharmacokinetics and pharmacodynamics.
Discuss the placenta's role in drug transfer to the fetus.
Discuss medication risk labeling in pregnancy, lactation, and reproduction.
Explain how neonates and pediatrics affect pharmacokinetics and pharmacodynamics.
Note special considerations for pediatric drug administration.
Explain how aging affects pharmacokinetics and pharmacodynamics.
Discuss special considerations in drug administration for the elderly.

Pregnancy

No further details

Pharmacokinetic Changes (Pregnancy)

Absorption: Decreased gastric emptying, increased blood flow, increased pH. Cardiac output increases blood flow to organs and tissues. IV/IM/SC absorption increases.
Distribution: Plasma volume increases 30-50%, decreasing circulating levels of some drugs. Body fat increases, which is a larger reservoir for lipophilic drug distribution. Protein dilution decreases protein binding.
Metabolism: Pregnancy hormones influence metabolic enzymes, creating a variable drug effect.
Elimination: Increased blood flow to the kidneys results in faster drug elimination. Tubular reabsorption increases, but hepatobiliary drug clearance decreases. Renal clearance can be difficult to predict.

Pharmacodynamic Changes (Pregnancy)

Increased sensitivity to anesthetics
Drug therapeutic indices may change
Fetal considerations

Transfer to the Fetus

The placenta is a semipermeable membrane that can metabolize some drugs.
Approximately 40-60% of umbilical venous blood flow enters the fetal liver and undergoes first-pass metabolism.
Drugs that increase placental transfer include lipophilic drugs, small molecular size drugs, drugs using placental transporters and drugs with a low degree of protein binding.

Pregnancy Risk Categorization

The FDA removed the A, B, C, D, and X categories from drug labeling.
Instead, labels now include a risk summary, clinical considerations and available drug data for Pregnancy, Lactation, and Females/Males of reproductive potential.

Nearpod Question 1

Discuss factors affecting drug and dose choices for a man or woman trying to conceive, a woman in her first trimester and a woman in labor.

Pediatrics

No further details

Pharmacokinetic Changes (Pediatrics)

The primary difference in pharmacokinetics in pediatrics is the change in body composition with age.
Lower muscle mass, lower body fat, lower plasma protein content, and higher total body water affect drug distribution and storage.
The blood-brain barrier is more permeable.

Pharmacokinetic Changes (Pediatrics) -- Absorption

Delayed gastric emptying (neonates), increased pH, delayed intestinal absorption (infants).
Thin stratum corneum (skin) increases absorption.
Variable IM absorption rates due to poor muscle mass, decreased movement, and increased capillary network.
Respiratory: High minute ventilation but low tidal volumes and flow rates leads to increased absorption of gases but decreased absorption of some drugs

Pharmacokinetic Changes (Pediatrics) -- Distribution

Greater for water-soluble drugs, lower for lipid-soluble drugs, decreased protein binding.
Immature blood brain barrier increases CNS distribution.

Pharmacokinetic Changes (Pediatrics) -- Metabolism

Phase I metabolism activity reduced in neonates.
Increases progressively during the first 6 months, exceeds adult rates by the first few years for some drugs, slows during adolescence, and attains adult rates by late puberty.
Drug metabolites eliminated primarily through bile or the kidneys.

Pharmacokinetic Changes (Pediatrics) -- Elimination

Decreased glomerular filtration rate (GFR) in infants results in reduced elimination
Decreased in tubular secretion leading to decreased elimination.

Pharmacodynamic Changes (Pediatrics)

Respiratory immaturity
Limited cardiovascular compensation
Hypoglycemia risk
Vulnerable to CNS depression

Nearpod Question 2

How does the age of an infant, toddler, and teenager affect drug, dose, and frequency choices?
Factors to consider for each age group.

Pediatric Drug Administration

Intramuscular injections: use smaller gauge needle, site varies, volumes depend on age.
Subcutaneous injections: Use 27 or 23 gauge needle in the upper arm.
Intravenous injections: Appropriate size for the vein.
Oral administration: Absorption variable, vomiting, use needle-less syringe.
Other routes: Rectal, topical (vasoconstriction common in young children).

Nearpod Question 3

A patient with generalized malaise provides a blister pack of medications without labels. How to identify the medications?

Nearpod Question 4

Discuss common social complications regarding medication adherence in the elderly. (e.g., issues like confusion, memory loss, difficulties accessing medications, understanding directions).

Geriatrics

No further details

Pharmacotherapy in the Elderly

Prevalence of prescription drug use increases substantially with age. (Most older adults frequently take multiple medications)
Despite decrease in gastric pH and gastric emptying, drug absorption is not drastically disturbed.
Elderly are more likely to have chronic disorders that may worsen due to drug effects
Mobility and fixed incomes can affect affordability / availability

Table of Changes in Aging

Data presented in a table format. (e.g. Body water, lean body mass, body fat, serum albumen, kidney weight, and hepatic blood flow)

Pharmacokinetic Changes (Geriatrics) - Absorption

Delayed gastric emptying, consumption of numerous medications and non-prescription drugs, altered nutritional habits.

Pharmacokinetic Changes (Geriatrics) - Distribution

Reduced lean body mass, total body water, and increased fat percentage.

Pharmacokinetic Changes (Geriatrics) - Metabolism

Reduction in Phase I metabolism
First-pass metabolism impacted by aging (decreases by about 1 percent per year after age 40)
Co-morbidities affect cardiac output.

Pharmacokinetic Changes (Geriatrics) - Elimination

Reduced renal clearance: maintenance doses may need adjustments in ill or dehydrated patients.

Pharmacodynamic Changes (Geriatrics)

No further details

Problematic Drugs in Elderly

List of problematic medications and conditions to consider.

Categorizes causes of preventable drug-related events.

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Description

This quiz explores the changes in pharmacokinetics and pharmacodynamics that occur in older adults, particularly after the age of 40. It covers topics such as first-pass metabolism, medication dosage adjustments, and the impact of gastrointestinal physiology during pregnancy on drug absorption. Test your knowledge on how these factors affect drug efficacy and safety in elderly patients.