Tobramycin dosage

Vandenbussche HL, Homnick DN. Evaluation of serum concentrations achieved with an empiric once-daily tobramycin dosage regimen in children and adults with cystic fibrosis. J Pediatr Pharmacol Ther 2012 17(l) 67-77. 

Newer examples of aminoglycoside antibiotics include amikacin, neomycin (Neosporin, Cortisporin), and tobramycin (TOBI, TobraDex). Injectable tobramycin is used in the treatment of serious infections at many body sites. It has also been formulated in an inhalable dosage form that has a very specific use to treat cystic fibrosis patients having Pseudomonas aeruginosa lung infections. In the form suitable for inhalation by the patient, it delivers the antibiotic directly to the site of infection. 

The dosage (5-7 mg/kg/d) and the routes of administration are the same as for gentamicin. Netilmicin is completely interchangeable with gentamicin or tobramycin but is no longer available in the USA. 

Tobramycin is available as a topical ophthalmic solution and an ointment (see Table 11-5). Tobramycin is also prepared as a topical fortified solution for the treatment of corneal ulcers and is used in place of fortified gentamicin using the same dosage schedule (see Table 11-1). 

De Broe ME, Verbist L, Verpooten GA. Inflnence of dosage schednle on renal cortical accnmnlation of amikacin and tobramycin in man. J Antimicrob Chemother 1991 27(Snppl C) 41-7. 

Sanchez-Alcaraz A, Vargas A, Quintana MB, Rocher A, Querol JM, Poveda JL, Hermenegildo M. Therapeutic drug monitoring of tobramycin once-daily versus twice-daily dosage schedules. J Clin Pharm Ther 1998 23(5) 367-73. 

In a comparison of different dosage regimens, inhaled tobramycin caused bronchial obstruction (12). However, after 10 minutes of inhalation, lung function returned to baseline the effect was independent of dose. 

Reduced tobramycin clearance can be associated with a normal creatinine clearance in serum concentration-adjusted dosage of once-daily tobramycin therapy in critically ill patients (42). 

Based on a study of 10 patients with automated peritoneal dialysis, it was recommended that for empirical treatment of dialysis-related peritonitis, the dosage of intermittent intraperitoneal tobramycin must be 1.5 mg/ kg for one exchange during the first day and then 0.5 mg/ kg thereafter, to reduce the risk of adverse effects (47). 

Concomitant administration of piperacillin and cephaloridine to rabbits resulted in a significant protective effect against cephaloridine nephrotoxicity [153]. Cephaloridine nephrotoxicity can be prevented by administration of other cephalosporins or penicdhns that produce little or no reduction of the cortical concentration of cephaloridine [154]. However, ceftriaxone protects against tobramycin nephrotoxicity by reducing the intracortical accumulation of tobramycin [155]. Combination of tobramycin with latamoxef protects the rat kidney from tobramycin nephrotoxicity, and the protective effect may be partially due to suppression of intrarenal accumulation of tobramycin by latamoxef. This suppression of nephrotoxicity is roughly dependent on the latamoxef dosage [81,156]. 

Studies in infants have shown that tobramycin clearance during the first postnatal week may increase with an increase in gestational age. In infants up to 1 month after birth, postnatal age also was correlated directly with aminoglycoside clearance. Thus premature infants require a lower daily dose of drugs eliminated by the kidney during the first week of fife the dosage requirement then increases with age. 

The antimicrobial activity, pharmacokinetic properties, and toxicity profile of tobramycin (nebcin) are very similar to those of gentamicin. Dosages and serum concentrations are identical with those for gentamicin. Tobramycin (tobrex) also is available in ophthalmic ointments and solutions. 

It is not known how important this interaction is likely to be in practice, but the efficacy of tobramycin in gut decontamination may be decreased. Separating the dosages might not be effective in some postoperative patients because their gastric function may not return to normal for up to 5 days, and some sucralfate might still be present when the next dose is given. More study is needed to find out whether this interaction is clinically important, but in the meanwhile it would seem prudent to monitor concurrent use carefully, being alert for any evidence of reduced effects. 

Monitoring of SDD is still in its infancy and quite different from conventional models in that peaks in excess of 20 pg/mL for gentamicin and tobramycin are anticipated. Dosages used varied from 3 to 7 mg/kg/day for gentamicin, tobramycin, and netilmicin and from 14 to 20 mg/kg/day for amikacin. Modification is recommended for increasing dosing interval to every 36 hours for creatinine clearance between 40 and 59 mL/min and to 48 hours for creati-... 

DeBroc ME. Influence of dosage schedules on renal cortical accumulation of amikacin and tobramycin in man. J Antimicobr Chemother 1991 27(supp C) 41-47. 

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