Therapeutic and Toxic Levels of Drugs

Table 56-1 Reference Intervals and Values Table 56-2 Therapeutic and Toxic Levels of Drugs Table 56-3 Critical Values...

TABLE 56-2 Therapeutic and Toxic Levels of Drugs—Continued ... 

Table 8.3 Comparative serum concentrations (mg/ml) of drugs at therapeutic and toxic levels...

Nurses must carefully monitor the patient s blood levels of drugs to ensure that they remain within the therapeutic range Any deviation should be reported to the primary health care provider. Because some dragp can cause toxic reactions even in recommended doses, the nurse should be aware of the signs and symptoms of toxicity of commonly prescribed drugs. 

The plasma half-life of hydralazine may be increased fourfold or fivefold in patients with renal failure. If renal failure is present, therefore, both the antihypertensive and toxic effects of hydralazine may be enhanced. Since A-acetylation of hydralazine is an important metabolic pathway and depends on the activity of the enzyme A-acetyltransferase, genetically determined differences in the activity of this enzyme in certain individuals (known as slow acetylators) wih result in higher plasma levels of hydralazine therefore, the drug s therapeutic or toxic effects may be increased. 

Similarly, the peaks between doses should not exceed toxic levels. Together, the minimum effective concentration and toxic level define the therapeutic window of the drug. 

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