Elimination (pharmacokinetics)
The elimination (also eliminating called) referred pharmacokinetic processes of degradation of certain exogenous substances to its elimination. Chemical reactions in the liver ( biotransformation ) and excretion via the kidneys and bile play an important role here.
excretion
In the organism, a main distinction is made between a renal ( Latin : ren = kidney) and a hepatic ( Greek : hepar = liver) (or hepatogenic or biliary / fecal) route of elimination. Organic substances that have to be eliminated can be classified according to their solubility, according to which a distinction is made between lipophilic (fat-loving), hydrophilic (water-loving) and amphiphilic (both fat-loving and water-loving) substance classes. Amphiphilic substances are eliminated through both excretory systems. Furthermore, excretion via breast milk, sweat, saliva and breath should also be mentioned. As a rule, however, the amounts are small and negligible from a pharmacokinetic point of view. An exception here are narcotics, which are mainly excreted or exhaled via the lungs (pulmonary) .
Renal excretion
During renal elimination , predominantly water-soluble, i.e. hydrophilic substances are excreted via the kidneys. Fat-soluble substances are also filtered in the kidney corpuscles ( glomeruli ), but they get back into the bloodstream via reabsorption in the kidney tubules. Furthermore, some substances can form strong bonds with albumin, a blood protein, and are not even affected by the filtration.
Hepatic excretion
Above all lipophilic substances fall into the excretion type of hepatic elimination . Most of these are broken down by the liver during the first passage through the liver ( first pass effect ) and excreted into the intestinal tract via the bile. Substances not absorbed ( absorbed ) by the intestinal cells ( intestinal mucosa ) and bound in the bile leave the body as feces.