Key Pharmacokinetic Processes to Know for Intro to Pharmacology

Pharmacokinetic processes are essential for understanding how drugs move through the body. Key steps include absorption, distribution, metabolism, and excretion, all of which influence a drug's effectiveness, safety, and overall therapeutic impact.

1. Absorption

   • The process by which a drug enters the bloodstream from its site of administration.
   • Influenced by factors such as drug formulation, route of administration, and gastrointestinal pH.
   • Affects the onset of action and overall effectiveness of the drug.

2. Distribution

   • Refers to the dispersion of a drug throughout the body's fluids and tissues.
   • Factors include blood flow, tissue permeability, and protein binding.
   • Determines the concentration of the drug at the site of action and its therapeutic effects.

3. Metabolism

   • The biochemical transformation of a drug into its active or inactive metabolites.
   • Primarily occurs in the liver through enzymatic processes.
   • Affects drug duration of action and potential toxicity.

4. Excretion

   • The elimination of drugs and their metabolites from the body, primarily through the kidneys.
   • Can also occur via bile, sweat, saliva, and exhalation.
   • Critical for preventing drug accumulation and toxicity.

5. Bioavailability

   • The fraction of an administered dose of a drug that reaches systemic circulation.
   • Influenced by the route of administration and first-pass metabolism.
   • Essential for determining the appropriate dosage and effectiveness of a drug.

6. Half-life

   • The time it takes for the concentration of a drug in the bloodstream to reduce by half.
   • Influences dosing frequency and duration of action.
   • A key factor in understanding drug clearance and accumulation.

7. First-pass effect

   • The initial metabolism of a drug by the liver before it reaches systemic circulation.
   • Can significantly reduce the bioavailability of orally administered drugs.
   • Important for determining the appropriate route of administration.

8. Volume of distribution

   • A theoretical volume that describes how extensively a drug disperses throughout the body.
   • Influenced by factors such as tissue binding and body composition.
   • Helps in understanding drug dosing and potential toxicity.

9. Clearance

   • The rate at which a drug is removed from the body, typically measured in volume per time.
   • Affects the drug's half-life and overall duration of action.
   • Important for determining appropriate dosing regimens.

10. Steady-state concentration

    • The point at which the rate of drug administration equals the rate of elimination.
    • Achieved after approximately 4-5 half-lives of the drug.
    • Critical for maintaining therapeutic drug levels and ensuring efficacy.