Effect
In their chemical structure, all penicillins have a so-called beta-lactam ring, a stop sign-shaped structure that inhibits the cell wall formation of the bacteria. Some bacteria have an enzyme called betalactamase as a defence mechanism. This enzyme is able to split the ring of the antibiotic and thus limit or render the drug ineffective.
However, some penicillins are betalactamase-resistant and can resist bacterial attack. They are mainly used by the bacteria that have the enzyme. Some penicillins are acid stable, others are not.
The acid-stable ones can be administered in tablet form because they can pass through the stomach without being dissolved and inactivated there. The non-acid-stable penicillins must be administered by infusion through the blood to bypass the stomach and gastric acid. The orally ingested penicillin G has good tissue mobility and passes into the skin, mucosa, liver, lungs and kidneys.
It is not transported via the cerebral fluid (liquor) and should not be used for diseases of the central nervous system. It does not develop an intracellular effect and is excreted unchanged via the kidneys to 90%.
