Once-daily aminoglycosides in patients with neutropenic fever

Current use of aminoglycosides: indications, pharmacokinetics and monitoring for toxicity

The new Australian Therapeutic Guidelines: Antibiotic, version 14 have revised the recommendations for the use and monitoring of aminoglycosides. The guidelines have clear distinctions between empirical and directed therapy as well as revised recommendations about the monitoring of aminoglycosides. This has led many clinicians to review their current practice with regard to the use of aminoglycosides. This review summarizes why aminoglycosides are still a valid treatment option and discusses the rationale for current dosing regimens in Gram-negative infections. In particular it focuses on the various methods for monitoring aminoglycosides that are currently being used. The aminoglycoside monitoring methods can be categorized into three groups: linear regression analysis (one compartment model), population methods and Bayesian estimation procedures. Although the population methods are easy to use and require minimal resources they can recommend clinically inappropriate doses as they have constant pharmacokinetic parameters and are not valid in special population groups, that is, renal impairment. The linear regression and Bayesian methods recommend more accurate dosage regimens; however, they require additional resources, such as information technology and healthcare personnel with background training in pharmacokinetics. The Bayesian methods offer additional advantages, such as calculation of doses based on a single serum concentration and optimization of the patient's previous pharmacokinetic data, in order to determine subsequent dosage regimens. We recommend the Bayesian estimation procedures be used, wherever feasible. However, they require the expertise of healthcare practitioners with a good understanding of pharmacokinetic principles, such as clinical pharmacists/clinical pharmacologists, in order to make appropriate recommendations.

Extended-interval aminoglycoside therapy for adult patients with febrile neutropenia: a systematic review

BACKGROUND

Although the efficacy and toxicity of extended-interval (once-daily) aminoglycoside regimens is well established for immunocompetent patients, there is clinical concern about using this regimen for patients with neutropenia.

OBJECTIVE

To summarize and evaluate the literature reporting the clinical efficacy and safety of extended-interval aminoglycosides therapy in adults with febrile neutropenia.

METHODS

A literature search was conducted within PubMed, Embase, and the Cochrane Database of Systematic Reviews to identify studies assessing the use of extended-interval aminoglycosides for treating febrile neutropenia in adults. Articles were categorized by quality of evidence, according to the rating scale of the US Preventive Services Task Force.

RESULTS

TEN ARTICLES WERE IDENTIFIED: 5 with level I evidence, 1 with level II-2 evidence, and 4 with level III evidence. Review of the 5 studies with level I evidence (all open-label randomized controlled trials), which compared extended-interval dosing with multiple-daily dosing strategies, revealed no evidence to suggest superiority of one regimen over the other in terms of clinical outcomes. In the study with level II-2 evidence (a prospective comparative trial), the response rate was better in the extended-interval group than in the standard-therapy group. Two of the studies with level III evidence (both prospective noncomparative trials) also had acceptable response rates to extended-interval aminoglycoside therapy, with minimal associated nephrotoxicity. In this review, no major differences in rates of nephrotoxicity or ototoxicity were seen between the 2 dosing regimens.

CONCLUSIONS

The use of extended-interval dosing for aminoglycosides, in combination with other recommended antibiotic therapy, is an effective and safe management strategy for immunocompromised patients with febrile neutropenia. In this population, the clinical efficacy and safety of extended-interval dosing does not appear to differ from those of standard dosing. Whether routine or selective pharmacokinetic monitoring in this patient subpopulation leads to improvements in outcomes is yet to be determined.

Aminoglycoside drugs in clinical practice: an evidence-based approach

Resistant bacteria have renewed our interest in the aminoglycoside drugs. Evidence on the efficiency of aminoglycosides in their different clinical uses is available from numerous randomized controlled trials and has been accrued and examined in recent systematic reviews and meta-analyses. Their results show that aminoglycosides should not be added to broad-spectrum beta-lactams to achieve synergism in treating Gram-negative infections as combination does not improve efficacy and adds side effects. The evidence from randomized trials in humans does not support the use of aminoglycosides in staphylococcal or streptococcal endocarditis, and is lacking for endocarditis caused by enterococci. Aminoglycosides are efficacious and safe as single drugs for the treatment of pyelonephritis and sepsis of a urinary source, but their efficacy might be lower than that of beta-lactams in Gram-negative infections of other sources. In patients with no risk factors, aminoglycosides are as safe as beta-lactams regarding side effects. They probably induce less resistance. Pragmatic large trials are needed to answer open clinical questions on the use of aminoglycosides.

Shifting to outpatient management of acute myeloid leukemia: a prospective experience

BACKGROUND

We assessed the feasibility of outpatient chemotherapy and supportive care in patients with acute myeloid leukemia (AML).

PATIENTS AND METHODS

All patients receiving curative intent chemotherapy between 09/01 and 10/02 and meeting our criteria received supportive care post induction chemotherapy as well as their entire consolidation chemotherapy cycles as outpatients. Patients received antimicrobial prophylaxis; those developing episodes of fever and not meeting the criteria for admission were treated with outpatient intravenous antibiotics.

RESULTS

Seventy-one cycles of induction chemotherapy were administered for newly diagnosed or relapsed AML. In 25 cycles the patient was discharged post chemotherapy prior to count recovery. Of these, 14 patients developed one or more febrile episodes as an outpatient and nine (36%) required readmission to hospital. Sixty-seven consolidation cycles were given on an outpatient basis. In 39 cycles there was one or more febrile episodes and in 14 (21%) admission was required. Infections were documented in four cases during induction and in 27 during consolidation. There were no treatment-related deaths.

CONCLUSIONS

Outpatient management of AML is safe and feasible using the strategies outlined in this report.

Preparation and characterization of dehydration–rehydration vesicles loaded with aminoglycoside and macrolide antibiotics

Enhanced activity of liposomes-encapsulated antibiotics against clinical isolates of Pseudomonas aeruginosa has been documented with liposomes of low encapsulation efficiency. We sought to construct liposomes with high yield entrapment of aminoglycoside and macrolide antibiotics as well as favorable stability in storage and physiological conditions. Liposome-entrapped aminoglycosides (amikacin, gentamicin, tobramycin) and a macrolide (erythromycin) were prepared by a modified dehydration-rehydration vesicles (DRVs) method, and their particle size and entrapment efficiency were determined. We studied in vitro stability of these vesicles over a 48 h period at 4 and 37 degrees C in phosphate-buffered saline (PBS) and in plasma at 37 degrees C. The mean particle size of DRVs loaded with antibiotics varied from 163.37+/-38.44 to 259.83+/-11.80 nm with no significant difference in regard with the type of the antibiotics encapsulated. Encapsulation efficiency of DRVs loaded with amikacin, gentamicin, tobramycin, and erythromycin were 29.27+/-1.17, 33+/-0.76, 22.33+/-1.48 and 32.06+/-0.82% of initial amount of the drug, respectively. These vesicles were stable regardless of the experimental temperature. Indeed, the liposomes retained more than 75% of the initially encapsulated drugs for the study period of 48 h. DRVs incubated in plasma however, released more antibiotics than those incubated in PBS. In conclusion, using this modified DRV method, we obtained small sized vesicles with high yield entrapment for aminoglycoside and macrolide antibiotics. The technique may be utilized to overcome the low encapsulation efficiency associated with aminoglycoside and macrolide antibiotics.