a. The average dose, also called the usual dose, is the amount of drug that
ordinarily produces the effect for which the drug is intended. In addition to the usual
dose, the usual dose range is often indicated for many drugs in standard pharmacy
references. This provides a guide to dispensing personnel in deciding whether the
prescriber should be consulted about the correctness of a prescribed dose. The usual
dose range is the range of doses that consistently produce the effect for which the drug
b. The minimum dose is the smallest dose that produces a therapeutic effect.
c. The maximum dose is the largest dose that can be safely administered.
d. The toxic dose is the dose that produces harmful effects.
e. The lethal dose is the dose that will result in death. The minimum lethal dose
(MLD) is the smallest amount that will cause death.
f. The single dose is the amount of a drug taken at one time. The daily dose is
the total amount of a drug taken in 24 hours. A continuous dose consists of small doses
taken at short intervals. A maintenance dose is that amount of drug taken to replace
previous doses that have been inactivated, detoxified, or excreted. The purpose of a
maintenance dose is to maintain the required concentration of the drug in the body.
FACTORS AFFECTING DRUG ACTION
In drug administration, many factors affect the action of the medication. These
factors also affect the dose to be administered. The usual adult dose of medication as
listed in standard references, is based on the assumption that the adult weighs 150
pounds, but since the following variables influence the action of the medication, they
also may alter the quantity of the drug necessary to produce the desired results.
a. Weight. Heavy, burly clients require larger doses than weak, emaciated
ones. The doses of many drugs are calculated on a weight basis; a specified number of
grams or milligrams are administered per pound or kilogram of body weight.
b. Age. As a rule, the very young and the very old require less than the normal
adult dose. As you recall from lesson 1, several formulas are available for estimating a
child's dose when the average adult dose is known.
c. Sex. Females usually require smaller doses than males. Iron preparations
and other hematinics are exceptions to this rule because of the blood lost by women
d. Race. Race can be a factor affecting drug action, since enzyme systems,
body chemistry, and stature may vary.