Plasma Halflife And Steadystate Concentration

The manner in which plasma drug concentration rises or falls when dosing is begun, altered or ceased follows certain simple rules, which provide a means for rational control of drug effect. Central to understanding these is the concept of half-life (t¥.) or half-time. Consider the time course of a drug in the blood after an i.v. bolus injection, i.e. a single dose injected in a period of seconds as distinct from a continuous infusion. Plasma concentration will rise quickly as drug enters the blood to reach a peak; there will then be a sharp drop as the drug distributes round the body (distribution phase), which will be followed by a steady decline as drug is removed from the blood by the liver or kidneys (elimination phase). If the elimination processes are first-order, the time taken for any concentration point in the elimination phase to fall to half its value is always the same; in other words, the t]/2, which is the time taken for the plasma concentration to fall by half, is a constant, as is illustrated in Figure 7.2. Note that from the peak concentration the drug is virtually eliminated from the plasma in 5 t^ periods.

Constipation Prescription

Constipation Prescription

Did you ever think feeling angry and irritable could be a symptom of constipation? A horrible fullness and pressing sharp pains against the bladders can’t help but affect your mood. Sometimes you just want everyone to leave you alone and sleep to escape the pain. It is virtually impossible to be constipated and keep a sunny disposition. Follow the steps in this guide to alleviate constipation and lead a happier healthy life.

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