Aminoglycosides renal elimination

Aminoglycosides are almost exclusively eliminated by glomerular filtration. Elimination is dependent on cardiovascular and renal function, age, fever, other physiological factors and the V. The half-lives are usuaUy 1-2 h in normal adult horses but are increased in horses with renal dysfunction and in neonates. Increased dosage intervals must be used in these patients to prevent nephrotoxicity. The renal elimination of the aminoglycosides increases with age. The half-life of gentamicin is approximately 50% longer in 1-day-old than in 30-day-old foals. 

Aminoglycosides are polar compounds, not absorbed orally or widely distributed into tissues. Renal elimination is proportional to GFR, and major dose reduction is needed in renal dysfunction. 

Renal elimination of drugs also is reduced in the neonatal period. Neonates at term have markedly reduced GFR (2-A mL/min/1.73 m ), and prematurity reduces renal function even further. As a result, neonatal dosing regimens for a number of drugs (e.g., aminoglycosides) must be... 

Renal failure will result in a diminished elimination of drugs that are primarily secreted, such as penicillins and aminoglycosides, and therefore in a longer half-life of the drug (45). Likewise, liver disease may result in a capacity-limited biotransformation, and consequently in a slower elimination of the drug. Bacterial pneumonia in calves may also result in increased serum oxytetracycline concentrations, a condition that can cause prolonged elimination (46). 

Mechanism uncertain. Metformin does not undergo hepatic metabolism. Renal tubular secretion is the major route of metformin elimination. Aminoglycosides are also principally excreted via the kidney, and nephrotoxicity is an important side-effect Watch and monitor for hypoglycaemia, and warn patients about it - For signs and symptoms of hypoglycaemia, see Clinical Features of Some Adverse Drug Interactions, Hypoglycaemia... 

Elimination. Renal blood flow, glomerular filtration and tubular secretion decrease with age above 55 years, a decline that is not signalled by raised serum creatinine concentration because production of this metabolite is diminished by the age-associated diminution of muscle mass. Indeed, in the elderly, serum creatinine may be within the concentration range for normal young adults even when the creatinine clearance is 50 ml/min (compared to 127 ml/min in adult male). Particular risk of adverse effects arises with drugs that are eliminated mainly by the kidney and that have a small therapeutic ratio, e.g. aminoglycosides, chlorpropamide, digoxin, lithium. 

Because of the slow elimination (long half-life) of antimicrobial agents in reptiles, dosage intervals are substantially longer in reptilian compared with mammalian species (Jacobson, 1993) (Table 6.14). To avoid significantly decreased systemic availability of drugs that are eliminated by renal excretion (e.g. (3-lactam and aminoglycoside antibiotics), the site of intramuscular injection should be the anterior half of the body most reptilian species have a well-developed renal portal system. 

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