Chapter 51: Pharmacokinetics

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Questions and Answers

What is a primary reason medications may cause toxicity in individuals with liver disease or failure?

Enhanced metabolism of medications

Impaired metabolism of medications (correct)

Increased body surface area

Increased gastric emptying time

Why are body surface area (BSA) calculations used in medication dosing?

To account for individual variations in body fat percentage (correct)

To account for individual variations in liver function

To account for individual variations in body weight

To account for individual variations in kidney function

What is a key factor to consider when administering medications to newborns and infants?

Mature liver and kidney function

Acidic gastric juices

Mature blood-brain barrier

Immature liver and kidney function (correct)

Why do older adults often require proportionately smaller medication doses?

Due to decreased kidney function Signup and view all the answers

What is a potential consequence of prolonged gastric emptying time?

Delayed medication absorption Signup and view all the answers

Why do males and females sometimes have varied responses to medications?

Due to differences in liver and kidney function Signup and view all the answers

What is a common method for calculating pediatric medication dosages?

Based on body weight Signup and view all the answers

What is a potential consequence of kidney disease or failure?

Delayed medication excretion Signup and view all the answers

Why do providers base some medication dosages on age?

Due to greater risk of acute cardiopulmonary failure and hepatic toxicity Signup and view all the answers

What is the primary concern when administering medications to children?

Medication errors Signup and view all the answers

Why are initial pediatric dosages considered an approximation?

Due to limited testing on children Signup and view all the answers

What is pharmacodynamic tolerance?

Reduced responsiveness to a medication over time Signup and view all the answers

Why is it essential to check that dosages are accurate for weight or BSA in children?

To avoid increased risk of medication toxicity Signup and view all the answers

What requires special preparation and administration in pediatric patients?

IV medications Signup and view all the answers

What is an essential step in promoting adherence to medication regimens in children?

Providing written and verbal instructions to parents Signup and view all the answers

What occurs when clients take medications that cause metabolic tolerance?

Medication effectiveness declines over time Signup and view all the answers

What is the primary reason for medication accumulation in older adults?

Decreased kidney and liver function Signup and view all the answers

In children, what factor contributes to increased absorption of topical medications?

Greater blood flow to the skin and thinner skin Signup and view all the answers

What is the result of decreased protein-binding sites in the blood in pediatric patients?

Increased blood level of protein-binding medications Signup and view all the answers

What is cross-tolerance related to in medication administration?

Chemically similar medications Signup and view all the answers

What is the result of decreased gastric acid production and slower gastric emptying time in pediatric patients?

Decreased first-pass medication absorption Signup and view all the answers

Why is medication accumulation a concern in pediatric patients?

Because of the inability to metabolize or excrete a medication rapidly enough Signup and view all the answers

What is a characteristic of older adults that affects medication administration?

Higher body water content Signup and view all the answers

What is the result of medication accumulation in the body?

A toxic medication effect Signup and view all the answers

Which of the following contributes to the potential for medication toxicity in older adults?

Diminished bodily functions and medical problems Signup and view all the answers

Why is it essential to monitor clients who are lactating when administering medications?

Medications taken during lactation enter breast milk Signup and view all the answers

What is a common problem that can contribute to the potential for medication toxicity in older adults?

Polypharmacy Signup and view all the answers

Why is it essential to consider reproductive potential when administering medications?

All of the above Signup and view all the answers

What is a concern when managing chronic medical disorders, such as diabetes mellitus and hypertension, in pregnant clients?

Maternal-fetal monitoring Signup and view all the answers

Study Notes

Pharmacokinetic Factors in Children

Decreased gastric acid production and slower gastric emptying time affect medication absorption.
Decreased first-pass medication absorption due to liver immaturity.
Increased absorption of topical medications due to greater blood flow to the skin and thinner skin.
Higher body water content dilutes water-soluble medications.
Decreased protein-binding sites in the blood (until age 1 year) increase blood levels of protein-binding medications.

Pharmacological Factors in Older Adults (65+ Years)

Decreased kidney and liver function lead to medication accumulation and toxicity.
Liver disease or failure impairs medication metabolism, causing toxicity.
Kidney disease or failure prevents or delays medication excretion, causing toxicity.
Prolonged gastric emptying time delays medication absorption in the intestines.

Physiological Changes with Aging

Body weight affects medication absorption, with greater body mass requiring larger doses.
Body surface area (BSA) is a more precise method of regulating medication response.
Age affects liver and kidney function, leading to heightened sensitivities to medications.
Sex affects medication response, with varied therapeutic responses in males and females.
Genetic factors (missing enzymes) alter medication metabolism, enhancing or reducing medication action.
Biorhythmic cycles affect medication response, with some medications working better at specific times.

Special Considerations for Children

Pediatric dosages are based on body weight or BSA.
Newborns and infants (2 days to 1 year old) have immature liver and kidney function, alkaline gastric juices, and an immature blood-brain barrier.
Be cautious when administering medications to children due to increased risk of medication errors, decreased skeletal bone growth, acute cardiopulmonary failure, and hepatic toxicity.
Check dosages for accuracy based on weight or BSA.
Initial pediatric dosages are approximations.
Most medications do not undergo testing on children.
Medication forms and concentrations may require dilution, calculation, preparation, and administration of very small doses for children.
Limited sites exist for IV medication administration.
Give written and verbal instructions to parents to promote adherence to medication regimens.

NURSING INTERVENTIONS

Obtain a complete medication history, including prescription medications, OTC medications, recreational drugs, and herbal supplements to reduce the risk of adverse effects.
Start medication therapy at the lowest effective dosage for the shortest possible time to minimize risk of adverse effects.
Assess and monitor for therapeutic and adverse effects, and monitor plasma medication levels to provide a rational basis for dosage adjustment.
Assess and monitor for medication-medication and medication-food interactions.
Notify the provider of adverse effects and ensure the client understands the effect of prescribed medications on reproductive potential.

REPRODUCTIVE POTENTIAL

Some medications include special considerations for clients of reproductive potential to reduce the risk of fetal harm and preserve reproductive ability.
Pregnancy testing before and during medication therapy, and beginning or altering contraceptive use may be necessary.
Ensure the client understands the effect of prescribed medications on reproductive potential and any specific actions to take during medication use.

PROMOTING ADHERENCE

Give clear and concise instructions, verbally and in writing, to ensure the client understands the medication regimen.
Ensure the dosage form is appropriate and administer liquid forms to clients who have difficulty swallowing.
Provide clearly-marked containers that are easy to open.
Be particularly alert when administering medications to children due to the increased risk of medication errors.

SPECIAL CONSIDERATIONS

Providers base some medication dosages on age due to a greater risk of decreased skeletal bone growth, acute cardiopulmonary failure, and hepatic toxicity in children.
Genetic factors can alter the metabolism of certain medications, thus enhancing or reducing a medication's action.
Responses to some medications vary with the biologic rhythms of the body, and tolerance to medications can develop over time.
Limited sites exist for IV medication administration in children, and most medications do not undergo testing on children.

MEDICATION THERAPY IN PREGNANCY AND LACTATION

Providers manage chronic medical disorders in conjunction with careful maternal-fetal monitoring during pregnancy.
Pregnancy is a contraindication for live-virus vaccines, and clients who are lactating should avoid medications that have an extended half-life, are sustained-release, or are harmful to infants.
Administer medications that are safe during lactation immediately after breastfeeding to minimize the medication's concentration in the next feeding.

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Description

This quiz covers pharmacokinetic factors unique to children, including cross-tolerance, gastric acid production, and medication absorption. Understand how children's bodies process medications differently.