An aminoglycoside is an antibiotic from the oligosaccharide group (carbohydrates made from several of the same or different simple sugars). Aminoglycoside antibiotics have a bactericidal effect.
What is an aminoglycoside?
Aminoglycosides represent a heterogeneous group among antibiotics, which are classified as oligosaccharides. They are used to treat bacterial infections. They are administered in the form of injections, as creams or as eye or ear drops. A drug from this antibiotic group is administered in the form of tablets. Aminoglycosides represent a combination of amino sugar and cyclohexane building blocks and are soluble in water. The half-life is about two hours, and excretion occurs primarily through the kidneys. The first aminoglycoside antibiotic discovered was streptomycin in 1944, and subsequently more and more similar agents were isolated. Division into aminoglycosides for the treatment of general infections (e.g., amikacin, gentamicin, tobramycin) and for the treatment of specific cases (e.g., streptomycin, neomycin, paromomycin) occurred.
Pharmacological effects on the body and organs
Aminoglycosides have a strong bactericidal effect. They penetrate bacteria, where they attach to ribosomes. These are cell organs for the formation of proteins. By blocking the ribosomes, the proteins are formed incorrectly and thus lose their function. The bacteria die as a result. Aminoglycosides penetrate the bacterium either through the pores of the cell walls or directly through the cell membrane, which explains the rapid onset of action. However, only bacteria that require oxygen to live react sensitively. Therefore, aminoglycosides are not effective against anaerobic bacteria. Aminoglycosides act within the bacteria, causing pathogens to die even several hours after administration, depending on the concentration of the active ingredient. The effect diminishes significantly if a second dose is administered too soon after the initial dose. A high single dose of aminoglycosides therefore produces a better effect than several doses given in quick succession. Accumulation of aminoglycosides occurs primarily in the kidneys and inner ear tissues. The risk of poisoning therefore increases with increasing duration of application. Run-off only occurs if the concentration is higher than in the blood. Therefore, it is important that the concentration in the blood is checked regularly by the doctor.
Medical use and use for treatment and prevention.
Aminoglycosides provide destruction of various pathogens. Taken orally, they act in the small and large intestines; in the case of creams, they act in a limited way on the skin; and when injected, they act in the entire organism. Orally, neomycin and paronomycin are given, which are supposed to ensure a germ-free intestine. They are used before operations, in coma, in “poisoning” of the brain due to liver failure, in leukemia or in granulocytopenia. Framycetin, kanamycin and neomycin are used for external application in bacterial infections of the skin or eyes. Parenteral administration of amikacin, gentamicin, netilmicin, or tobramycin is used for pathogens such as Staphylococcus aureus or streptococcus type A. For tuberculosis, parenteral administration of streptomycin is used, and for life-threatening blood poisoning, amikacin, gentamycin, netilmycin, or tobramycin is administered in combination with beta-lactam antibiotics. These two groups of antibiotics complement each other in their action, but must not be mixed together in an infusion. The aminoglycosides amikacin, gentamycin, netilmycin and tobramycin are used to treat endocarditis (inflammation of the inner wall of the heart) or severe infections (e.g. caused by Pseudomonas aeruginosa, listeria, enterococci, mycobacteria, enterobacteria, staphylococci). Other active ingredients include apramycin and hygromycin. Spectinomycin is a similarly acting agent that is used only in the treatment of uncomplicated gonorrhea if penicillins are ineffective. It must be administered parenterally, especially for systemic infections, because aminoglycosides are not absorbed. Patients with intolerance to the active ingredients must not receive aminoglycosides.
Risks and Side Effects
Dosing of aminoglycosides must be done carefully because of their narrow therapeutic range.They are therefore typical antibiotics for use in intensive care medicine. Aminoglycosides accumulate particularly in the kidney and inner ear and have a nephrotoxic (mostly reversible) and vestibulo- and ototoxic (mostly irreversible) effect here. The effect of neuromuscular blocking substances is often prolonged by aminoglycosides. Typical side effects are usually nausea and vomiting, drowsiness, and ataxia (disturbances in the coordination of movements). Long duration of use (more than three days), frequent administration, high dosage, preexisting renal disease, older age, and high blood levels may increase the risk for side effects.
