Tobramycin nephrotoxicity. A prospective clinical study

Antibacterial Efficacy of Liposomal Formulations Containing Tobramycin and N-Acetylcysteine against Tobramycin-Resistant Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii

The antibacterial activity and biofilm reduction capability of liposome formulations encapsulating tobramycin (TL), and Tobramycin-N-acetylcysteine (TNL) were tested against tobramycin-resistant strains of E. coli, K. pneumoniae and A. baumannii in the presence of several resistant genes. All antibacterial activity were assessed against tobramycin-resistant bacterial clinical isolate strains, which were fully characterized by whole-genome sequencing (WGS). All isolates acquired one or more of AMEs genes, efflux pump genes, OMP genes, and biofilm formation genes. TL formulation inhibited the growth of EC_089 and KP_002 isolates from 64 mg/L and 1024 mg/L to 8 mg/L. TNL formulation reduced the MIC of the same isolates to 16 mg/L. TNL formulation was the only effective formulation against all A. baumannii strains compared with TL and conventional tobramycin (in the plektonic environment). Biofilm reduction was significantly observed when TL and TNL formulations were used against E. coli and K. pneumoniae strains. TNL formulation reduced biofilm formation at a low concentration of 16 mg/L compared with TL and conventional tobramycin. In conclusion, TL and TNL formulations particularly need to be tested on animal models, where they may pave the way to considering drug delivery for the treatment of serious infectious diseases.

Tobramycin for the treatment of bacterial pneumonia in children

INTRODUCTION

Common etiological agents for community-acquired lower respiratory tract infection (LRTI) include Streptococcus pneumoniae, Hemophilus influenzae and Mycoplasma pneumoniae and can be easily managed with oral or intravenous antibiotics. However, LRTI in patients with underlying illnesses, such as cystic fibrosis (CF) and immune deficiency, or on ventilator support is difficult to manage because these are caused by Gram-negative bacilli. Tobramycin has been shown to be effective in the management of these patients.

AREAS COVERED

Information about the antimicrobial activity, pharmacological aspects (including pharmacokinetics and pharmacodynamics), clinical efficacy, safety and side effects of tobramycin have been covered in this review.

EXPERT OPINION

A major advance for the use of tobramycin has occurred with its use by the inhalational route, in children with CF. The inhalation route provides the advantage of ease of administration for prolonged periods at home and allows use of very high doses. Systematic reviews suggest that tobramycin inhalation improves outcome, decreases the need for hospitalization and decreases the need for use of frequent systemic antibiotics in CF patients colonized with pseudomonas. Data on the efficacy of inhaled tobramycin in non-CF bronchiectasis are scarce, as are data on the prevention and treatment of ventilator-associated pneumonia, and on the role of combining inhaled tobramycin with systemic tobramycin. Despite limitations, this drug has the potential to be used in various conditions other than CF.

Aminoglycoside-associated Severe Renal Failure in Patients with Multiple Myeloma Treated with Thalidomide

Thalidomide has been proved to play an important role in rescue treatment of patients with refractory/relapsed multiple myeloma (MM). However, thalidomide therapy is associated with numerous side effects, mainly somnolence, constipation, fatigue or peripheral neuropathy. We report three patients diagnosed with MM and treated with thalidomide as salvage therapy who developed severe renal failure when they received aminoglycoside antibiotics. This observation suggests that thalidomide can potentiate nephrotoxicity of aminoglycoside antibiotics in patients with MM.

Clinical pharmacokinetics, toxicity and cost effectiveness analysis of aminoglycosides and aminoglycoside dosing services

This article reviews the clinical pharmacokinetics, clinical toxicity and cost-effectiveness analysis of aminoglycosides and of dosing services for aminoglycosides. The reader is referred elsewhere for a review of the pharmacology, antimicrobial spectrum of activity and clinical use of these drugs. A critique of the more commonly used methods of aminoglycoside dosage determinations is included, based on the inter-individual variation in aminoglycoside disposition parameters. The advantages and disadvantages of arbitrary, predictive, and pharmacokinetic methods of dosing determination are summarized. Justification for the routine determination of serum aminoglycoside concentrations is reviewed. We review the lack of standardization of definitions for aminoglycoside-associated nephrotoxicity in published studies, and studies which illustrate these differences are highlighted. Evidence for the association between serum aminoglycoside concentrations and nephrotoxicity is examined. Ototoxicity is similarly reviewed. The concept of cost-effectiveness analysis is examined extensively in this review. We discuss the literature concerning the cost benefit analysis of drug dosing services.

Comparison of drug dosing methods

The literature reviewed herein clearly demonstrates the poor correlation between drug dosing and the ability to achieve a specific serum drug concentration and between drug dosing and clinical response, especially for drugs with a narrow therapeutic index. There is, however, a better correlation between serum drug concentration and observed clinical response. Thus, clinicians use serum drug concentrations to more accurately dose drugs. Numerous dosing methods have been developed in an attempt to improve the relationship between dosing, serum drug concentration, and response. The major hypothesis is that if dosing methods can be developed that will accurately predict serum drug concentrations, these methods would be useful in improving clinical care. Several dosing methods have been developed including use of 'standard' doses, population-based predictive algorithms and nomograms, pharmacokinetic equations, and Bayesian feedback. Some of these methods are accurate and useful, whereas others are not. This review evaluates the commonly used dosing methods (some of which utilise serum drug concentration feedback for dosage estimation) for 5 drugs: gentamicin, digoxin, phenytoin, theophylline, and lignocaine (lidocaine). These drugs were selected since they exhibit a representative cross section of pharmacokinetic parameters and since they exhibit a representative cross section of pharmacokinetic parameters and since they have narrow therapeutic ranges. An individualised method and a Bayesian method, both using serum drug concentration feedback, appear most accurate and precise in dosing to achieve desired serum drug concentrations and, hence, response. Our bias from personal experience with this method and from published use by others is that the Bayesian method is more flexible in that any number of serum drug concentrations may be used to determine dose, instead of the 3 or more required for the individualised method. Although use of these methods would appear to be cost-effective in timely provision of health care by reduction of toxicity and hospital stay, only sparse data have been generated to support this conclusion. Thus, further examination of the cost-effectiveness of drug dosing methods is necessary to establish their place in routine patient care.

Prospective randomized double-blind comparison of nephrotoxicity and auditory toxicity of tobramycin and netilmicin

Netilmicin or tobramycin was administered to 197 patients in a prospective randomized double-blind trial. Of these patients, 140 recipients of nine or more doses of netilmicin or tobramycin could be evaluated for nephrotoxicity. Fifty-five patients were able to cooperate in the administration of serial audiograms. Nephrotoxicity of similar severity developed in 7 of 73 (9.6%) recipients of tobramycin and in 7 of 67 (10.4%) recipients of netilmicin (P greater than 0.05). Mild or slight auditory toxicity developed in 5 of 28 (17.8%) recipients of tobramycin and in 2 of 27 (7.4%) recipients of netilmicin (P greater than 0.05).

Comparison of the nephrotoxicity and auditory toxicity of tobramycin and amikacin

A total of 157 patients were treated with tobramycin or amikacin in a controlled prospective randomized trial. Dosages were adjusted to renal function according to a nomogram. Trough and peak aminoglycoside levels were available at the end of the trial. Of the above total, 113 recipients of nine or more doses of tobramycin or six or more doses of amikacin, without other apparent cause of renal failure, were evaluated for nephrotoxicity. Thirty-six patients were evaluated for auditory toxicity. The patients in groups evaluated for either nephrotoxicity or auditory toxicity were similar with respect to intensity and etiology of bacterial disease, concurrent exposure to other antimicrobial drugs, age and sex distribution, initial serum creatinine level, and total dose and duration of antimicrobial therapy. Nephrotoxicity of similar severity developed in 4 of 59 (6.8%) recipients of tobramycin and in 7 of 54 (13.1%) recipients of amikacin (P greater than 0.05). Mild auditory toxicity developed in 3 of 19 (15.7%) recipients of tobramycin and in 2 of 17 (11.7%) recipients of amikacin (P greater than 0.05). When patients with abnormally high mean trough or peak aminoglycoside levels were excluded from comparison, nephrotoxicity was 6.12 and 5.12% (P greater than 0.05) and auditory toxicity was 17.6 and 7.69% (P greater than 0.05) in the groups given tobramycin and amikacin, respectively. We conclude that the nephrotoxicity and auditory toxicity of amikacin and tobramycin are not significantly different and that such toxicities are indeed infrequent events when the dosages of these drugs are adjusted to hold blood levels within the safe boundaries suggested by the studies of others.