Concentration mgLDose mg

FIGURE 5-4 Frequency distribution curves and quantal concentration—effect and dose-effect curves. A. Frequency distribution curves. An experiment was performed on 100 subjects, and the effective plasma concentration that produced a quantal response was determined for each individual. The number of subjects who required each dose is plotted, giving a log-normal frequency distribution (colored bars). The gray bars demonstrate that the normal frequency distribution, when summated, yields the cumulative frequency distribution—a sigmoidal curve that is a quantal concentration-effect curve. B. Quantal dose-effect curves. Animals were injected with varying doses of sedative-hypnotic, and the responses were determined and plotted. The calculation of the therapeutic index, the ratio of the LD50 to the ED50, is an indication of how selective a drug is in producing its desired effects relative to its toxicity. (See text for additional explanation.)

patient in the hospital and about 0.4% per each course of therapy. Adverse reactions to drugs are the most common cause of iatrogenic disease.

Mechanism-based adverse drug reactions are extensions of the principal pharmacological action of the drug. These would be expected to occur with all members of a class of drugs having the same mechanism of action.

When an adverse effect is encountered infrequently, it may be referred to as idiosyncratic (i.e., it does not occur in the population at large). Idiosyncratic adverse effects may be mechanism-based (e.g., angioedema on angiotensin-converting enzyme inhibitors) or off-target reactions (e.g., anaphylaxis to penicillin). Investigations of idiosyncratic reactions often have identified a genetic or environmental basis for the unique host factors leading to the unusual effects.

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Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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