Action and Rationale for Use

Diuretics increase the formation and excretion of urine. These drugs are used as antihypertensive agents because of their ability to increase the renal excretion of water and sodium, thus decreasing the volume of fluid within the vascular system. This situation is somewhat analogous to the decrease in pressure that would occur inside a balloon if some of the air inside were allowed to leak out. Consequently, diuretics appear to have a rather direct effect on blood pressure 

Category Primary Site(s) of Action Primary Antihypertensive Effect(s) 

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The many available types of laxatives are usually classified by their apparent mode of action.22 27 35 Often, two different laxatives, either from the same class or from two different classes, are combined in the same commercial preparation. Some of the more common laxatives, listed by their apparent mechanisms of action, are in Table 27-4. The major laxative classes and rationales for their use are outlined in the next few sections. 

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