Chapter 6: Individual Variation in Drug Responses

Question 1

individual variation in drug responses

Answer 1

Key factors that cause one patient to respond to drugs differently than another patient​

Important for nurses to know these factors to be better prepared to reduce individual variation in drug responses

Question 2

variation in drug responses: body weight and comp

Answer 2

body surface area vs weight

Question 3

variation in drug responses: age

Answer 3

Significant variability with age​

Infants and older patients especially sensitive to drugs​

Infants: Organ immaturity​

Older patients: Organ degeneration​

Due to increased severity of illness, multiple pathologies, treatment with multiple drugs

Question 4

variation in drug responses: patho

Answer 4

Kidney disease​: Reduced excretion and increased toxicity​

Liver disease​: Reduced metabolism and increased toxicity​

Acid-base imbalance​: pH changes that alter absorption, distribution, metabolism, and excretion of drugs​

Altered electrolyte status​: Rare for electrolyte changes to have a significant impact on drug responses

Question 5

variation in drug responses: tolerance

Answer 5

Decreased responsiveness to a drug as a result of repeated drug administration​

Higher doses required

Question 6

3 types of drug tolerance

Answer 6

Pharmacodynamic tolerance​ -Associated with long-term administration of drugs such as morphine and heroin​

Metabolic tolerance​ -Results from accelerated drug metabolism​

Tachyphylaxis​ -Reduction in drug responsiveness brought on by repeated dosing over a short time

Question 7

placebo effect

Answer 7

Any response that a patient has to a placebo is based solely on his or her psychologic reaction to the idea of taking a medication and not to any direct physiologic or biochemical action of the placebo itself​

Nurses need to present a positive but realistic assessment of the effects of therapy​

Placebos are primarily used for the control groups in clinical trials

Question 8

variability in absorption

Answer 8

Bioavailability​

Ability of the drug to reach the systemic circulation from its site of administration​

Occurs primarily with oral preparations rather than with parenteral administration​

Tablet disintegration time, enteric coatings, and sustained-release formulations affect this​

Other causes of variable absorption​ -Changes in gastric pH, diarrhea, constipation, and food in the stomach

Question 9

genetics

Answer 9

Pharmacogenomics: Study of how genes affect individual drug responses​

Altered drug metabolism​ -May accelerate or delay the metabolism​, Warfarin, succinylcholine, isoniazid, cytochrome P450​

Altered drug targets​
Genetic variations alter the structure of drug receptors​

Question 10

variations: gender

Answer 10

Alcohol is metabolized more slowly by women than by men​

Certain opioid analgesics are much more effective in women than in men​

Quinidine causes greater QT interval prolongation in women than in men

Question 11

variations: race

Answer 11

Genetic variations​

Psychosocial factors

Question 12

variations: comorbidities

Answer 12

increased likelihood of drug interactions

Question 13

variations: diet

Answer 13

Starvation can reduce protein binding of drugs​

Monoamine oxidase inhibitors: Malignant hypertension triggered by foods that contain tyramine​

Question 14

other variations

Answer 14

psychosocial

Question 15

variations: failure to take meds as prescribed

Answer 15

Issues include manual dexterity, visual acuity, intellectual capacity, psychologic state, attitude toward drugs, and ability to pay for medication

Question 16

drug interactions

Answer 16

one drug alters the effects of another