FIG. 4

The solid line is the pharmacokinetic function consistent with a two-compartment model (Eq. 1) after rapid intravenous injection of a hypothetical drug (dose = D). The elimination half-life in the post-distributive phase is 6 hr. The horizontal dotted line represents the minimum effective concentration (M.E.C.), below which the drug has no clinical activity. Note that the duration of activity of the drug is short (less than 2 hr) because the plasma concentration falls below the M.E.C. during the distribution phase. The dashed line represents the function corresponding to an administration of the same drug at twice the dose (dose = 2D). Note that doubling the dose disproportionately prolongs the duration of action.

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published 2000