Pharmacology & Dosage
Intermediate

Loading Dose

Initial higher dose to rapidly achieve the desired plasma concentration.

Formula

LD=Ctarget×VdFLD = \frac{C_{target} \times V_d}{F}

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Variables

LDLoading dose
C_{target}Target plasma concentration
V_dVolume of distribution
FBioavailability

Example

Ctarget = 15 mg/L, Vd = 40 L, F = 0.8 → LD = 750 mg

Did You Know?

Digoxin and many antibiotics require loading doses because waiting for steady state would take dangerously long.

pharmacologyloading doseinitialdosing

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Drug Half-Life

Intermediate

Time for the plasma concentration of a drug to fall to half its initial value.

Steady-State Concentration

Intermediate

Average plasma drug concentration when intake and elimination are balanced.

Maintenance Dose

Intermediate

Recurring dose needed to sustain the steady-state concentration.

Volume of Distribution

Basic

Apparent volume into which a drug distributes — a larger Vd means the drug leaves the bloodstream and enters tissues.

Clearance

Intermediate

Volume of plasma completely cleared of a drug per unit time.

Bioavailability

Intermediate

Fraction of an oral dose that reaches systemic circulation compared with an IV dose.