Although optimum values may vary, periodic measurements of both peak and trough concentrations of amikacin are recommended to ensure adequate drug levels and prevent toxic side effects. The most serious toxic effect is permanent damage to the vestibular division of the eighth cranial nerve, which has been reported to occur most frequently in patients with renal failure. Amikacin is inherently stable, is not metabolized, and is excreted primarily by glomerular filtration.
Therefore, the presence of renal impairment drastically alters its pharmacokinetics. If dosage regimens are not drastically adjusted, excess accumulation leading to ototoxicity and further renal impairment could be encountered. While elevated serum levels can be toxic, indiscriminately low dosages of amikacin will result in ineffective treatment for many strains of gram-negative bacteria. Organisms which are resistant to amikacin will often show increased resistance to all other available aminoglycosides. This observation points out the possibility that the indiscriminate use of low dosages of amikacin could engender the emergence of drug-resistant organisms and possibly render the drug ineffective in treating infectious disease.
Each laboratory should investigate the transferability of the expected values to its own patient population and, if necessary, determine its own therapeutic range.