Clinical Pharmacokinetics: General Principles of Clinical Pharmacokinetics

Pharmacokinetics

Pharmacokinetics produces descriptions of concentration changes of drugs within the body.

"Target" tissue concentrations would be ideal:

1. Adequate research has rarely been done
2. Interpretations are often "biased"

Serum concentrations are the "coin of the realm":

1. Serum concentrations predict effects for MOST therapeutic agents.
2. Serum concentrations are better correlated to effects than are doses.

Application: Evaluation and Prediction

Clinically useful pharmacokinetics PREDICTS the time course of concentrations that will result following a given dose of a drug.

Usual cases:

• Standard doses produce therapeutic, non-toxic concentrations.

Special cases:

• "Standard" doses are not efficacious or are toxic because narrow therapeutic index, disease affects disposition, drug interactions.
• Doses and intervals should be adjusted to accommodate patient abnormalities.

"Rational Dose Adjustment"

• Understand impact of disease on drug disposition.
• Select dose and interval based on "educated guess".

Therapeutic Concentration Monitoring

• Determine plasma or serum concentrations that result from drug administration to YOUR patient.
• Determine pharmacokinetics (calculation) for the drug in YOUR patient.
• Dose patient on the basis of their own pharmacokinetics.