The renal toxicity of
gentamicin is altered by
dietary protein modifications,
bicarbonate and
acetazolamide administration,
magnesium supplementation,
polyaspartic acid,
piperacillin,
hypercalcemia and
calcium channel blockers. Renal tissue
gentamicin levels have an undetermined role. Reduction of renal
pyridoxal 5'-phosphate (PLP- by
gentamicin has been shown, as has protection from nephrotoxicity by administration of
vitamin B6. To explore an interaction between
gentamicin and
vitamin B6,
gentamicin (5 mg/kg) was given to rabbits by ip injection, with either
pyridoxine (10 mg) or isovolemic saline for 3 weeks. There was not a difference between
gentamicin levels for animals given
gentamicin and
pyridoxine versus those given
gentamicin and saline.
Gentamicin administration led to a 47% fall (p = .0001) in plasma PLP levels. Three days after the last
gentamicin administration, the animals maintained a 32% decrease from the pre-
gentamicin baseline values (p = 0.02). When
pyridoxine was administered concurrently with
gentamicin, the PLP rise of 49% was significant (p = 0.001). The mean level after the study (6%) was not significantly lower than baseline (p = .6). We believe that
gentamicin interfers with
vitamin B6 metabolism, but that
vitamin B6 status does not affect levels of
gentamicin. A number of drugs affect B6 levels, creating the potential for hypovitaminosis B6 to be an important mechanism of
drug-drug interaction in seriously ill patients, particularly in sick newborns or the elderly with lower average PLP levels.