Intravenous administration of gentamicin once daily versus thrice daily in adults

Destination of aminoglycoside antibiotics in the 'post-antibiotic era'

Aminoglycoside antibiotics (AGAs) were developed at the dawn of the antibiotics era and have significantly aided in the treatment of infectious diseases. Aminoglycosides have become one of the four major types of antibiotics in use today and, fortunately, still have an important role in the clinical treatment of severe bacterial infections. In this review, the current usage, modes of action and side effects of AGAs, along with the most common bacterial resistance mechanisms, are outlined. Finally, the recent development situation and possibility of new AGAs in the 'post-antibiotic era' are considered.The Journal of Antibiotics advance online publication, 25 October 2017; doi:10.1038/ja.2017.117.

Once-Daily Aminoglycosides: A Meta-Analysis of Nonneutropenic and Neutropenic Adults

Objective:

To compare the efficacy, nephrotoxicity, and ototoxicity of once-daily dosing of aminoglycosides versus conventional dosing.

Design:

Meta-analysis of 14 randomized trials identified through a MEDLINE search (January 1965-May 1996).

Patients:

Neutropenic and nonneutropenic adults.

Interventions:

Patients were randomly selected to receive an aminoglycoside once daily or in multiple daily doses.

Measurements and Main Outcomes:

The outcomes considered were clinical cure, bacteriologic cure, nephrotoxicity, auditory toxicity, and vestibular toxicity. The data were analyzed in the following subgroups: (1) all trials, (2) nonneutropenic patients, (3) neutropenic patients, and (4) patients with undefined neutrophil status. For all trials the pooled risk ratio was 1.268 (95% CI 0.828 to 1.939) for clinical cure, and was 1.390 (95% CI 1.350 to 1.392) for bacteriologic cure. Nephrotoxicity had a pooled risk ratio of 0.765 (95% CI 0.468 to 1.252), that for auditory toxicity was 1.117 (95% CI 0.151 to 5.636), and that for vestibular toxicity was 1.155 (95% CI 0.221 to 6.039). Analysis of the subgroups, including a separate analysis of neutropenic patients, demonstrated similar results.

Conclusions:

When all trials were considered, once-daily administration of aminoglycosides had similar efficacy and no increase in nephrotoxicity or ototoxicity compared with conventional aminoglycoside dosing.

Once versus individualized multiple daily dosing of aminoglycosides in critically ill patients

BACKGROUND AND OBJECTIVE

The purpose of this study was to evaluate the once daily dosing (ODD) program in critically ill Egyptian patients compared to individualized multiple daily dosing (MDD) in terms of clinical and bacteriological efficacy. In addition, the incidence of nephrotoxicity associated with both regimens in this specific group of patients was assessed.

METHODS

Fifty-two patients with suspected or confirmed bacterial infections admitted to the Critical Care Medicine Department, Kasr El-Aini-Cairo University Hospitals comprised the study population. The amikacin group (30 patients) was sub-divided into 14 patients receiving amikacin ODD (1 g i.v.) and 16 patients receiving amikacin in MDD (500 mg i.v./dose). The gentamicin group (22 patients) was sub-divided into 10 patients receiving the drug ODD (240 mg i.v.) and 12 patients receiving gentamicin MDD (80 mg i.v./dose). Amikacin or gentamicin serum levels were determined by the enzyme multiplied immunoassay technique using Emit 2000. MDD regimen was adjusted based on the individual pharmacokinetic parameters using the Sawchuk-Zaske method.

RESULTS

There was no significant difference between the two dosing regimens with regard to clinical and antibacterial efficacy or incidence of nephrotoxicity of both gentamicin and amikacin groups. In the ODD regimen, duration of treatment had no effect on increasing incidence of nephrotoxicity unlike the individualized MDD regimen. No dose adjustments were needed in the once daily dosing regimen since trough concentrations have never been above toxic level.

CONCLUSIONS

The study showed that the ODD regimen is preferred in critically ill patients to individualized MDD as shown by comparable efficacy, nephrotoxicity and lesser need for therapeutic drug monitoring and frequent dose adjustments required in the individualized MDD regimen.

Permanent Gentamicin Vestibulotoxicity

OBJECTIVE

To determine the natural history of permanent gentamicin vestibulotoxicity.

STUDY DESIGN

Retrospective; comparison of retrospective and prospective studies.

SETTING

Tertiary neurotology clinic. Clinical research and technology center.

SUBJECTS

Thirty-three subjects with permanent gentamicin-induced vestibulotoxicity.

INTERVENTIONS

Medical records review, neurotologic examination, and vestibular and auditory function tests.

MAIN OUTCOME MEASURES

Vestibular and auditory function test results at least 1 year after discontinuation of gentamicin, clinical examination results, serum gentamicin levels, and serum creatinine levels.

RESULTS

Thirty-three subjects had vestibular function test results consistent with permanent gentamicin ototoxicity. All complained of dysequilibrium, 32 described oscillopsia, and 23 had tinnitus. All 33 subjects had complained of symptoms consistent with ototoxicity within 1 to 3 weeks of initiation of gentamicin therapy; however, gentamicin vestibulotoxicity was not recognized before hospital discharge in 32 of 33 subjects. Serum peak and trough gentamicin levels did not correlate with the development of vestibulotoxicity, nor did observance of recommended "safe" dosage ranges. Of 17 subjects whose serum creatinine levels were recorded, 6 experienced abnormal elevations in serum creatinine in conjunction with gentamicin use.

CONCLUSION

Gentamicin can cause permanent vestibular and auditory ototoxicity. There is no safe dose of gentamicin. Serum gentamicin levels are of no value in predicting the onset, occurrence, or severity of vestibulotoxicity or cochleotoxicity. Termination of gentamicin on appearance of signs or symptoms of ototoxicity may reduce the incidence of permanent vestibular ototoxicity. When possible, other antibiotics should be administered.

Screening and prevention of hearing loss in children

Congenital hearing loss is the most common neurosensory handicap in neonates. Recently, technology has become available that has allowed states to implement universal screening programs at a relatively low cost and with minimal expertise needed for hospital personnel to operate the screening machines. In successful programs, the age of diagnosis has been reduced from 2(1/2) years to 3 to 6 months. Children diagnosed with hearing loss before speech develops have been shown to have better speech and language outcomes than those who are diagnosed later. Strategies for screening and early intervention are discussed, as well as the causes, prevention, and treatment of more common forms of childhood hearing loss.

Global problem of drug-induced hearing loss

Clinically used drugs and chemical agents may potentially cause adverse effects to the human auditory and vestibular systems. Many of them, such as aminoglycosides and cisplatin, can play a critical role in the treatment of serious or life-threatening diseases; others, like loop diuretics or salycilates, offer such important therapeutical effects compared to the ototoxic side effects that the ototoxicity risk can be considered to be of minor importance. The problem of ototoxic side effects is more acute in developing countries, where highly effective and low-cost drugs are more easily prescribed without adequate monitoring. Medical awareness of doses, forms of administration, populations at risk, and possible synergism is necessary in order to develop appropriate care in the prescription of drugs with ototoxic side effects. Relatively recent issues such as risk-benefit analysis, patient-informed consent, and quality-of-life considerations, particularly when life expectancy can be low, are also to be considered. At present, a uniform method of monitoring for all potentially ototoxic therapeutics does not seem reasonable or practical. It is recommended, however, that individual auditory function be noted for a particular drug being employed. Protocols and exams should be easy, quick, sensitive, reliable, and as objective as possible. Benefits of audiological monitoring include the opportunity to change the patient's treatment course, improvement of patient and family awareness of the impact of hearing impairment, and timely prescription of amplification devices. Finally, particular attention should be paid to high-risk populations such as neonatal intensive care unit patients.

Pharmacokinetics of single daily dose gentamicin in children with cancer

PURPOSE

To study the pharmacokinetics of single daily dose (SDD) gentamicin in children with cancer.

METHODS

Serum concentrations of gentamicin were prospectively measured at 0.5, 8, 16, and 24 hours after a single daily dose of gentamicin 6 mg/kg, given as a 30-minute infusion in 18 febrile children with cancer and a central venous catheter. Then the peak (0.5-hour) and 12-hour serum concentrations of gentamicin were prospectively measured after a SDD of 7 mg/kg during 73 febrile episodes in 54 pediatric cancer patients with suspected infections. The aim was to achieve a peak serum concentration of 15 to 20 microg/mL 10 times the minimum inhibitory concentration (MIC) for sensitive Pseudomonas strains, resulting in good bactericidal activity and a long post-antibiotic effect (PAE) after a SDD of gentamicin.

RESULTS

The mean serum peak gentamicin concentration 30 minutes after the end of the infusion of 6 mg/kg was 13.3 +/- 4.0 microg/mL. The mean serum concentration 16 hours after the infusion was 0.3 +/- 0.2 microg/mL. The mean peak and 12-hour serum concentration after SDD of 7 mg/kg was 17.2 +/- 3.9 microg/mL and 0.9 +/- 0.7 microg/mL, respectively. The mean peak serum concentration after SDD of 7 mg/kg in children younger than 5 years of age (16.1 +/- 3.5 microg/mL ) was significantly lower than that of children over 5 years of age (18.2 +/- 3.9 microg/mL; P = 0.02). The desired peak serum concentration was achieved in 67% of children younger and 84% of those older than 5 years of age.

CONCLUSION

Adequate peak serum concentrations of gentamicin in children may be obtained with a SDD of 7 mg/kg. Children younger than 5 years of age achieve lower peak serum gentamicin concentration after SDD of 7 mg/kg than those older than 5 years.

Once daily aminoglycoside therapy. Is it less toxic than multiple daily doses and how should it be monitored?

After 50 years of clinical experience with the aminoglycoside agents, there is continuing debate over the most appropriate administration regimen for these drugs. In recent years, once daily administration has been used increasingly, in the hope of both improving efficacy and reducing toxicity. At least 30 controlled clinical trials have compared once versus conventional multiple daily administration. Efficacy was assessed in some, but not all, studies using clinical and/or bacteriological cure. Toxicity was generally determined using rather nonsensitive end-points such as measurement of serum creatinine for nephrotoxicity and clinically detectable hearing loss for ototoxicity. The results of individual clinical trials and subsequent meta-analyses have been variable. However, 5 of 9 meta-analyses found clinical efficacy to be significantly better with once daily administration, and in 3 of the 9 there were significantly less nephrotoxicity with once daily administration. The results were not significant for ototoxicity in any of the meta-analyses. There is debate about how therapeutic drug monitoring should be performed, and whether it is still required with once daily administration. Previous experience with the aminoglycosides, especially in patients with impaired drug clearance caused by renal impairment, suggests that monitoring is still prudent. Results from the once daily administration trials appear to support this. Various methods of monitoring and dose adjustment have been proposed. The most common is to measure a 24-hour trough concentration and to adjust the dose to maintain the trough concentration below a value of 2, 1 or 0.5 mg/L. However, this method allows for greater total aminoglycoside exposure than has been permitted with conventional dosages, increasing the likelihood of toxicity in patients with impaired aminoglycoside clearance. Other methods measure drug concentrations at a time-point or points within the dose interval (when the concentration is still measurable), and adjust the dose according to concentration-time curve nomograms or to a target area under the concentration-time curve. This allows the use of higher doses in those with high drug clearance. Furthermore, in patients with impaired clearance, drug exposure is limited to the same extent as, or less than, that with conventional multiple daily administration. To date no controlled trials have compared methods of dose-individualisation. In summary, in addition to a slight overall improvement in efficacy, once daily administration has resulted in a small reduction in nephrotoxicity. In the studies using more sensitive measures of toxicity, the differences in toxicity were greater, strengthening the case for once daily administration. Therapeutic drug monitoring is probably required with once daily administration. Methods which use mid-dosage interval concentrations to gauge drug exposure would seem to be preferable over trough concentration measurement.

A randomized comparison of the safety and efficacy of once-daily gentamicin or thrice-daily gentamicin in combination with ticarcillin-clavulanate

PURPOSE

The primary purpose of the clinical trial was to assess the safety and efficacy of once-a-day compared with three-times-a-day gentamicin in patients with serious infections who had protocol-determined peak serum aminoglycoside concentrations.

PATIENTS AND METHODS

A total of 249 hospitalized patients with suspected or proven serious infections were randomized in a 2:2:1 ratio to gentamicin given three times a day with ticarcillin-clavulanate (TC), gentamicin once a day with TC, or ticarcillin-clavulanate (TC) alone. The gentamicin once-a-day dosage for patients with estimated creatinine clearance values of > or =80 mL/min was 5.1 mg/kg. With lower creatinine clearance estimates, the mg/kg dosage of gentamicin was decreased, and the dosage intervals (once daily or three times a day) were maintained. Evaluability required documentation of achievement of protocol-defined peak serum gentamicin levels.

RESULTS

Of the total 175 evaluable patients, there were no significant differences found between treatment regimens with respect to clinical or microbiologic efficacy. Bedside audiometry proved impractical due to the frequency of altered mental state in ill patients. Based on the traditional increase in serum creatinine values from baseline values, no differences in renal toxicity between the treatment groups was identified. When changes in renal function were reanalyzed based on maintaining, as opposed to worsening, of renal function, preservation of renal function was better in the gentamicin once-a-day patients as opposed to the gentamicin three-times-a-day patients, P <0.01.

CONCLUSIONS

Gentamicin once a day plus TC, gentamicin three times a day plus TC, and TC alone had similar effects in seriously ill hospitalized patients. The incidence of nephrotoxicity was similar in the three treatment groups. Using a nonvalidated post-hoc analysis, renal function was better preserved in gentamicin once-a-day + TC and TC-only patients as opposed to gentamicin three-times-a-day + TC.

Pharmacokinetic analysis of gentamicin thrice and single daily dosage in pediatric cancer patients

Fifty-two children suffering from different types of malignancies were included and evaluated for the pharmacokinetics of gentamicin thrice or single daily dosage protocols. All the study population received a total dose of 5 mg/kg daily. Thirty children received gentamicin thrice daily, and 22 were treated using the single daily protocol; all had fever and neutropenia when included. The individual pharmacokinetic parameters were calculated using a one-compartment model for two blood gentamicin samples. The mean (SD) t 1/2 (h), clearance (mL/min/BSA), Vss (L/kg), Cmax (micrograms/mL), and Cmin (micrograms/mL) were 3.05 (1.0) and 3.9 (0.6) h, 136 (61.3) and 99.9 (65.3) mL/min/BSA, 0.4035 (0.167) and 0.457 (0.17) L/kg, 5.2 (2.0) and 11.5 (4.2) micrograms/mL, 0.8 (0.6) and 0.18 (0.1) microgram/mL for thrice and single daily dosage schedules, respectively. The single gentamicin daily dose protocol had a significantly longer t 1/2, shorter clearance normalized to BSA, higher Cmax, and lower Cmin in comparison with the thrice daily schedule. We recommend the use of gentamicin at 5 mg/kg daily delivered as a single daily dose for pediatric cancer patients with fever and neutropenia, in spite of the measured pharmacokinetic differences, which in our opinion have no clinical significance.

Antimicrobial therapy for intraabdominal infection

Timely and appropriate antimicrobial therapy is an essential component of the management of intraabdominal infection. Over the past three decades, our ability to treat these infections optimally has been enhanced by an increased understanding of the underlying microbial pathogens, by the development of new antimicrobial agents, and by the completion of several well-controlled clinical trials that guide treatment. This article provides an overview of the approach to antimicrobial therapy in patients with intraabdominal infection. A literature review was performed to collect the information used in this article. Data were derived from experimental and clinical studies evaluating the microbiology and treatment of intraabdominal infections. Evidence from both animal studies and clinical trials supports the initiation of empiric antimicrobial therapy directed against Escherichia coli and other common members of the family Enterobacteriaceae, as well as the anaerobe Bacteroides fragilis. Based on this premise, the clinician is faced with a broad selection of possible single agents, as well as combinations of agents that fulfill these criteria. The factors involved in selecting a specific regimen include consideration of the antimicrobial spectrum of various agents, experimental animal studies evaluating their efficacy, and, importantly, efficacy in well-designed clinical trials. In addition, consideration of safety profiles, pharmacokinetics, and cost of specific pharmaceutical agents should be made when selecting a regimen. Antimicrobial therapy is an important component of the management of intraabdominal infection. The results of well-designed clinical trials evaluating various aspects of therapy should serve to guide treatment.

Efficacy and safety of once-daily amikacin in combination with ceftazidime in critically ill adults with severe gram-negative infections

Forty critically ill adult patients with severe Gram-negative infection were treated with once-daily amikacin combined with ceftazidime. The mean age was 56.6 +/- 19 years and mean APACHE II score was 22.7 +/- 6.6. Forty percent of patients required mechanical ventilation. The mean creatinine clearance at onset of therapy was 59.4 +/- 28 ml/min. All bacterial isolates were sensitive to amikacin. Fixed doses of amikacin 15 mg/kg, 12 mg/kg, and 8 mg/kg body weight were given once daily to patients with estimated creatinine clearance of > 80 ml/min., 50-80 ml/min., and < 50 ml/min, respectively. Forty-two causative gram-negative bacteria were isolated from 40 patients. The most common bacteria were Pseudomonas aeruginosa (18), and Escherichia coli (10). Overall clinical success and bacteriological eradication occurred in 85% and 87.5% of patients; 78.9% and 79% of patients with hospital-acquired infections; 90.5% and 95.2% of patients with community-acquired infections; and 62.5% and 81.3% of patients requiring mechanical ventilation, respectively. Therapeutic failure was documented in 15% of patients. Death due to infection was scored in two patients. The remaining were all due to persistence of the initial causative bacteria in patients with hospital-acquired infections. Persistence was documented with Ps. aeruginosa (2), Serratia spp. (1), and Acinetobacter spp. (1). Overall mortality occurred in 22.5% patients. Death unrelated to infection occurred in 7 patients. There was no clinical evidence of ototoxicity in any of our patients, however, nephrotoxicity was documented in 5%. In conclusion, once-daily amikacin combined with ceftazidime is practical, efficacious and probably safe in critically ill infected patients.

Kinetics of killing or growth of Trichomonas vaginalis in the presence of aminoglycosides, neomycin and geneticin (G418)

Few therapeutic drugs, other than metronidazole and close derivatives, are currently available to treat trichomoniasis. Trichomonas vaginalis is known to have a primitive ribosome based on small subunit ribosomal DNA sequence comparisons. Targeting ribosomal subunits, the aminoglycosides neomycin and geneticin (G418, distinct from gentamycin) were tested for activity against T. vaginalis. While neomycin had no effect, G418 was effective in killing cultured T. vaginalis cells at doses intermediate between those previously effective against prokaryotes and eukaryotes. G418 cytotoxicity requires further study before recommending this agent as topically applied therapy in refractory patients.

Once-daily dosing of aminoglycosides

Since their introduction one or more decades ago, aminoglycosides have generally been administered in multiple daily (i.e. twice- or thrice-daily) dosing regimens. However, nephrotoxicity can be reduced in animal models by administering the same total daily dose as one large dose instead of as multiple small doses. In addition, in vitro and in vivo studies that considered the impact of dosing regimens on efficacy suggest that once-daily dosing is equally or more effective compared to multiple daily dosing. Once-daily versus multiple daily dosing regimens have been compared for amikacin, netilmicin, and gentamicin in 24 randomized, clinical trials including a total of 3,181 patients. An analysis of these studies revealed superior results for once-daily regimens with respect to clinical efficacy (89.5% vs. 84.7%, p < 0.001) as well as bacteriological efficacy (88.6% vs. 83.4%, p < 0.01). No statistically significant differences were noted for toxicity. Nevertheless, both nephrotoxicity and ototoxicity occurred less frequently during once-daily dosing (4.5% vs. 5.5% and 4.2% vs. 5.8%, respectively). Finally, once-daily dosing is more economical, since less nursing time and infusion material are required and the efforts for drug monitoring can be reduced. In conclusion, amikacin, netilmicin, and gentamicin can be administered once a day.

Once-daily dosing regimen for aminoglycoside plus betalactam combination therapy of serious lower respiratory tract infections

Aminoglycosides are important antibacterial agents for treatment of serious gram-negative bacillary infections including lower respiratory tract infection. Once-daily aminoglycosides result in higher peak and lower trough plasma concentrations than conventional multiple daily dosing regimens; once-daily aminoglycoside therapy is equally effective, generally less toxic and much less expensive and therefore this regimen is more and more frequently used for treatment of suspected or confirmed gram-negative bacillary infections and of febrile episodes in neutropenic patients, in particular in combination with an appropriate betalactam antibiotic. Despite the lack of studies on this topic, once-daily aminoglycosides in combination with a betalactam agent can be used in subjects with lower respiratory tract infection, including patients with cystic fibrosis, in which tobramycin appears to be the aminoglycoside antibiotic of choice.

Preclinical and clinical evaluation of once-daily aminoglycoside chemotherapy

The rationale for and effectiveness of extended dosage intervals for aminoglycosides are reviewed. Aminoglycoside antibiotics have a prolonged postantibiotic effect against a variety of common Gram-negative and Gram-positive organisms: higher serum aminoglycoside levels are associated with a longer postantibiotic effect and increased bactericidal activity. Moreover once daily aminoglycoside administration may reduce the potential for adaptive postexposure resistance by allowing less contact time between bacteria and antibiotic. A longer dosage interval may decrease the risk of nephro- and ototoxicity. At least 33 published clinical trials suggest that once-daily administration of aminoglycosides and conventional regimens involving shorter dosage intervals are equally effective in patients with normal renal function and Gram-negative infections: besides, once-daily administration may reduce the frequency of aminoglycoside toxicity or delay it.