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Questions and Answers
What are the phases of pharmacokinetics?
What is the half-life of a drug?
Amount of time it takes for the blood concentration to drop by half of its original level.
What is the percentage of drug that is absorbed into the bloodstream known as? _______________
Bioavailability
Match the Age-Related Changes in Pharmacokinetic Processes:
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Tolerance can lead to drug addiction.
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Study Notes
Pharmacokinetics
- Deals with the kinetics of a drug, including absorption, distribution, metabolism, and elimination (ADME)
Pharmacokinetic Phases
- Absorption:
- Transport mechanisms: filtration, active transport, and passive transport
- Determined by lipid solubility, drug ionization, and formulation
- Distribution:
- Plasma protein binding
- Blood flow
- Blood-brain barrier
- Metabolism:
- Microsomal metabolizing system in the liver
- Enzymes within liver cells metabolize foreign substances
- Excretion:
- Renal excretion
- GI, sweat, saliva, and lactation
Clinical Factors That Determine the Intensity of Drug Response
- Half-life: time it takes for blood concentration to drop by half of its original level
- Blood drug levels: determine the intensity of a drug effect
- Bioavailability: percentage of drug absorbed into the bloodstream
- Clinical factors:
- Age
- Emotional state
- Weight
- Placebo effect
- Sex and percent body fat
- Disease state
- Genetic variation
- Patient compliance
Pharmacokinetic Considerations for Pediatrics
- Drug absorption differs in infants
- Infants have a small skeletal muscle mass and limited movement
- Distribution of drugs differs in infants
- Pharmacokinetic and pharmacodynamic differences exist between pediatric and adult patients
- Infants have a higher percentage of body water and a lower percentage of body fat
- Drug metabolism and excretion are slower in infants
Drug Use in the Elderly
- Geriatric: individuals over 65 years of age
- Aging affects drug absorption, distribution, metabolism, and excretion
- Age-related changes in pharmacokinetic processes:
- Decreased intestinal blood flow, surface area, and motility delay drug absorption
- Decreased body water, lean body mass, and plasma proteins increase plasma drug concentrations
- Decreased liver blood flow, liver organ size, and enzyme concentrations decrease drug metabolism
- Decreased renal function and blood flow slow drug excretion
Terminology Associated with Chronic Drug Use and Abuse
- Tolerance: decreased drug effect with repeated administration
- Cross-tolerance: tolerance that exists between drugs of the same class
- Dependence: reliance on a drug becomes vital to the well-being of the patient, leading to drug abuse or addiction
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Description
Learn about pharmacokinetics, the field of science that deals with the kinetics of drug Absorption, Distribution, Metabolism and Elimination.
