20.6j Medication Response Relationship

therapeutic effects

To have its optimal desired or (?), a medication must reach appropriate concentrations at its site of action.

magnitude of the response

The (?) therefore depends on the dosage and the course of medication through the body over time.

pharmacodynamic

Factors that can affect the medication’s concentration can be pharmaceutical (the dosage form’s disintegration and the medication’s dissolution), pharmacokinetic (the medication’s absorption, distribution, metabolism, and excretion), or (?) (medication-receptor interaction).

medication-response relationship

To predict how the medication will affect different people, a (?) thus correlates different amounts of medication with the resultant clinical response.

plasma-level profiles

Most of the information needed to describe medication-response relationships comes from (?), which describe the lengths of onset, duration, and termination of action as well as the medication’s minimum effective concentration and toxic levels.

onset of action

The (?) is the time from administration until a medication reaches its minimum effective concentration (the minimum level of medication necessary to cause a given effect).

duration of action

The length of time that the amount of medication remains above this level is its (?).

Termination of action

(?) is measured from when the medication’s level drops below the minimum effective concentration until it is eliminated from the body.

therapeutic index

The ratio of a medication’s lethal dose for 50 percent of the population (LD50) to its effective dose for 50 percent of the population ed5o) is its (?), or (LD50 / ED50).

margin of safety

The TI represents the medication’s (?).

value of TI

As the range between effective dose and lethal dose decreases, the (?) decreases; that is, it becomes closer to 1.

TI values close to 1

(?) indicate a very small margin of safety.

effective dose and lethal dose

In other words, the (?) of a medication whose TI value is close to 1 are nearly the same.

difficult to effectively dose

This medication would be very (?) without causing toxicity.

biologic half-life

The last component of the medication-response relationship, the (?), is the time the body takes to clear one-half of the medication.

independent of its concentration

Although the rates of metabolism and excretion both affect it, a medication’s half-life (t1/2) is (?).

half-life

For example, if the concentration of a medication were 500 mcg/dL after administration and 250 mcg/DL in 10 minutes, its (?) would be 10 minutes.

125 mcg/dL

After another 10 minutes, or (?), would remain.