Pharmacokinetics - Level Up RN

Introduction

• Presenter: Cathy from Level Up RN
• Invitation to subscribe for nursing content
• Focus of the video: Pharmacokinetics
• Four phases of pharmacokinetics: Absorption, Distribution, Metabolism, Excretion
• Quiz at the end to test understanding

Absorption

• Definition: How medication gets from the site of administration into the bloodstream
• IV Medication: Immediate absorption (directly into bloodstream)
• Oral Medication: Slower absorption (goes through the GI tract)
• Factors affecting absorption:
  • Solubility of the medication
  • Dose and formulation (liquid vs. tablet)
  • Surface area of the absorption site
  • Presence of food in the stomach
  • pH of stomach acid (more alkaline pH in older adults decreases absorption)

Distribution

• Definition: How medication gets from the bloodstream to the site of action
• Factors affecting distribution:
  • Plasma Protein Binding: Medications need proteins like albumin. Low albumin levels affect protein binding
  • Permeability at Destination Site: Non-lipid-soluble medications can't penetrate the blood-brain barrier
  • Circulation: Blood flow impacts distribution (e.g., peripheral arterial disease affects distribution to extremities)

Metabolism

• Definition: Inactivation of medications by enzymes
• Primary organ: Liver
• Other involved organs: GI tract, lungs, kidneys
• Factors influencing metabolism:
  • Liver Function: Impaired liver function (e.g., cirrhosis) affects metabolism
  • First-Pass Effect: Some medications become inactivated in the liver and need to be administered parenterally (e.g., IV, subcutaneous, intramuscular)
  • Other Factors: Genetics, sex, hormones, environmental factors, diet

Excretion

• Definition: Elimination of medications from the body
• Primary organ: Kidneys (via urine)
• Other routes: Saliva, sweat, tears, feces
• Factors affecting excretion:
  • Kidney or Liver Dysfunction: Impairs excretion
  • Urinary and Medication pH: Can affect excretion
  • Age: Newborns and older adults have decreased kidney and liver function, increasing risk for toxicity

Quiz

1. True/False: Older adults have a higher gastrointestinal pH which impairs absorption.
   • Answer: True
2. Question: How does a medication get from the bloodstream to the site of action?
   • Answer: Distribution
3. Question: What is the primary organ responsible for metabolism in the body?
   • Answer: Liver

Conclusion

• Encouragement to re-watch and review flashcards if necessary
• Invitation to subscribe, share, like, and comment