Dosage Regimen and Drug Concentration

Flashcards covering dosage regimens, steady-state drug concentrations, and loading doses.

Steady State

The point at which the amount of drug being administered equals the amount being eliminated, resulting in constant plasma and tissue levels (IV) or fluctuations around a mean (oral).

Half-life and Steady State

A drug generally reaches steady state in about 4 half-lives.

Repeated Oral Administration

Results in oscillations in plasma concentrations, influenced by drug absorption and elimination rates.

Single Fixed Dose (Oral)

Results in a single peak in plasma concentration, followed by a continuous decline in drug level.

Wash-out Period

The exponential decline of drug concentration after stopping drug infusion, with the same time constant as during infusion.

Maintenance Dose

The dosage regimen that maintains a steady-state concentration and requires four to five half-lives of a drug.

Loading Dose

An initial higher dose of a drug to achieve the desired plasma level rapidly, followed by a maintenance dose.

When to use Loading Dose

Loading doses are given when the half-life of the drug is long and the therapeutic benefit is required immediately (e.g., lidocaine for arrhythmias).

Loading Dose Disadvantage

Increased risk of drug toxicity.