Short answers, pulled from the story.
Pharmacokinetics describes how the body affects a specific substance after administration. Pharmacodynamics studies how the drug affects the organism while pharmacokinetics studies how the organism affects the drug.
The four main phases include absorption, distribution, metabolism, and excretion. Absorption represents the process of a drug entering systemic circulation from the site of administration. Distribution refers to the dispersion of substances throughout fluids and tissues of the body. Metabolism includes irreversible breakdown into metabolites by enzymes like cytochrome P450 or glucuronosyltransferase. Excretion marks the removal of the substance or metabolites from the body.
Steady state is reached after about 60 hours according to this data. This calculation assumes 5 times 12 equals 60 hours based on the elimination half-life showing the time required for concentration to reach half its original value at 12 hours.
Multi-compartment models provide best approximations to reality despite high complexity. Two-compartment models consider organs with well-developed blood supply versus those with lower blood flow. Monocompartmental models and two compartmental models remain most frequently used due to simplicity.
Intravenous administration provides the greatest possible bioavailability considered to yield 100 percent availability. Bioavailability remains a unitless factor representing the systemically available fraction of a drug at 0.8 in some examples.