Intravenous Pharmacokinetics and Pharmacodynamics

5.3
Intravenous Pharmacokinetics and Pharmacodynamics

  • Effective Dose50 (ED50) (Figure 5.6)
    • The median drug dose which is effective in 50% of the population
    • Similar to MAC for inhalational agents
  • Toxic Dose50 (TD50) (Figure 5.6)
    • The median drug dose which has a toxic side effect in 50% of the population
  • Lethal Dose50 (LD50) (Figure 5.6)
    • The median drug dose which is lethal in 50% of the population
A multi-line graph response of Individual in percent versus dose. The 3 S-shaped curves depict effective dose E D 50, Toxic D 50, and lethal D 50. Each dose reaches 50 % in response of individual. The therapeutic Index equals T D 50 divided by E D 50.

Figure 5.6

Factors Affecting Onset

  • Drug Solubility
    • ↓ Blood solubility → ↑ Blood saturation rate → ↑ Tissue uptake → ↑ Onset
  • Drug Concentration
    • ↑ Concentration → ↑ Onset
  • Tissue pH
    • Drugs ionization dependent on pH of surrounding tissues
    • ↑ Nonionized drug → ↑ Onset
      • Nonionized drugs more readily cross cell membranes and the BBB to exert their effects
    • Henderson–Hasselbalch equation determines nonionized/ionized drug ratio (Figure 5.7)
  • Plasma Protein Binding
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Oct 16, 2024 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Intravenous Pharmacokinetics and Pharmacodynamics

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