Safety and Effectiveness of Daptomycin Across a Hospitalized Obese Population: Results of a Multicenter Investigation in the Southeastern United States

Updated antimicrobial dosing recommendations for obese patients

The prevalence of obesity has increased considerably in the last few decades. Pathophysiological changes in obese patients lead to pharmacokinetic (PK) and pharmacodynamic (PD) alterations that can condition the correct exposure to antimicrobials if standard dosages are used. Inadequate dosing in obese patients can lead to toxicity or therapeutic failure. In recent years, additional antimicrobial PK/PD data, extended infusion strategies, and studies in critically ill patients have made it possible to obtain data to provide a better dosage in obese patients. Despite this, it is usually difficult to find information on drug dosing in this population, which is sometimes contradictory. This is a comprehensive review of the dosing of different types of antimicrobials (antibiotics, antifungals, antivirals, and antituberculosis drugs) in obese patients, where the literature on PK and possible dosing strategies in obese adults was critically assessed.

A machine learning approach to predict daptomycin exposure from two concentrations based on Monte Carlo simulations

Daptomycin is a concentration-dependent lipopeptide antibiotic for which exposure/effect relationships have been shown. Machine learning (ML) algorithms, developed to predict the individual exposure to drugs, have shown very good performances in comparison to maximum a posteriori Bayesian estimation (MAP-BE). The aim of this work was to predict the area under the blood concentration curve (AUC) of daptomycin from two samples and a few covariates using XGBoost ML algorithm trained on Monte Carlo simulations. Five thousand one hundred fifty patients were simulated from two literature population pharmacokinetics models. Data from the first model were split into a training set (75%) and a testing set (25%). Four ML algorithms were built to learn AUC based on daptomycin blood concentration samples at pre-dose and 1 h post-dose. The XGBoost model (best ML algorithm) with the lowest root mean square error (RMSE) in a 10-fold cross-validation experiment was evaluated in both the test set and the simulations from the second population pharmacokinetic model (validation). The ML model based on the two concentrations, the differences between these concentrations, and five other covariates (sex, weight, daptomycin dose, creatinine clearance, and body temperature) yielded very good AUC estimation in the test (relative bias/RMSE = 0.43/7.69%) and validation sets (relative bias/RMSE = 4.61/6.63%). The XGBoost ML model developed allowed accurate estimation of daptomycin AUC using C0, C1h, and a few covariates and could be used for exposure estimation and dose adjustment. This ML approach can facilitate the conduct of future therapeutic drug monitoring (TDM) studies.

Advances in antibacterial treatment of adults with high-risk febrile neutropenia

BACKGROUND

High-risk febrile neutropenia (HR-FN) is a life-threatening complication in patients with haematological malignancies or receiving myelosuppressive chemotherapy. Since the last international guidelines were published over 10 years ago, there have been major advances in the understanding and management of HR-FN, including on antibiotic pharmacokinetics and discontinuation/de-escalation strategies.

OBJECTIVES

Summarizing major advances in the field of antibacterial therapy in patients with HR-FN: empirical therapy, pharmacokinetics of antibiotics and antibiotic stewardship.

SOURCES

Narrative review based on literature review from PubMed. We focused on studies published between 2010 and 2023 about the pharmacokinetics of antimicrobials, management of antimicrobial administration, and discontinuation/de-escalation strategies. We did not address antimicrobial prophylaxis, viral or fungal infections.

CONTENT

Several high-quality publications have highlighted important modifications of antibiotic pharmacokinetics in HR-FN, with standard dosages exposing patients to underdosing. These recent clinical and population pharmacokinetics studies help improve management protocols with optimized initial dosing and infusion rules for β-lactams, vancomycin, daptomycin and amikacin; they highlight the potential benefits of therapeutic drug monitoring. A growing body of evidence also shows that antibiotic discontinuation/de-escalation strategies are beneficial for bacterial ecology and patients' outcome. We further discuss methods and limitations for implementation of such protocols in haematology.

IMPLICATIONS

We highlight recent information about the management of antibacterial therapy in HR-FN that might be considered in updated guidelines for HR-FN management.

Therapeutics for Vancomycin-Resistant Enterococcal Bloodstream Infections

Vancomycin-resistant enterococci (VRE) are common causes of bloodstream infections (BSIs) with high morbidity and mortality rates. They are pathogens of global concern with a limited treatment pipeline. Significant challenges exist in the management of VRE BSI, including drug dosing, the emergence of resistance, and the optimal treatment for persistent bacteremia and infective endocarditis. Therapeutic drug monitoring (TDM) for antimicrobial therapy is evolving for VRE-active agents; however, there are significant gaps in the literature for predicting antimicrobial efficacy for VRE BSIs. To date, TDM has the greatest evidence for predicting drug toxicity for the three main VRE-active antimicrobial agents daptomycin, linezolid, and teicoplanin. This article presents an overview of the treatment options for VRE BSIs, the role of antimicrobial dose optimization through TDM in supporting clinical infection management, and challenges and perspectives for the future.

Reporting of Drug-Induced Myopathies Associated with the Combination of Statins and Daptomycin: A Disproportionality Analysis Using the US Food and Drug Administration Adverse Event Reporting System

BACKGROUND

Myopathy is one of the most common adverse reactions of daptomycin and statins. We aimed to evaluate the muscular toxicity of the combination therapy of daptomycin and statins in a large pharmacovigilance database.

METHODS

This was a retrospective disproportionality analysis based on real-world data. All cases reported between the first quarter of 2004 and the fourth quarter of 2022 where daptomycin and statins were reported were gathered from the US Food and Drug Administration Adverse Event Reporting System (FAERS) database. Disproportionality analyses were conducted by estimating the proportional reporting ratios (PRRs), reporting odds ratio (ROR), and information component (IC).

RESULTS

A total of 971,861 eligible cases were collected from the FAERS database. Data analysis showed that rosuvastatin (ROR: 124.39, 95% CI: 87.35-178.47), atorvastatin (ROR: 68.53, 95% CI: 51.93-90.43), and simvastatin (ROR: 94.83, 95% CI: 71.12-126.46) combined with daptomycin increased the reporting frequency of myopathy. Moreover, myopathy was reported more frequently with the 3-drug combination (ROR: 598.01, 95% CI: 231.81-1542.71). For rhabdomyolysis, the frequency of reports also increased when daptomycin was combined with rosuvastatin (ROR: 156.34, 95% CI: 96.21-254.05), simvastatin (ROR: 72.65, 95% CI: 47.36-111.44), and atorvastatin (ROR: 66.31, 95% CI: 44.06-99.81).

CONCLUSIONS

The combination of daptomycin and statins increased the association of myopathy and rhabdomyolysis, especially with rosuvastatin, simvastatin, and atorvastatin.

Daptomycin-Rifampin-Induced Rhabdomyolysis, Acute Renal Failure, and Hepatic Injury: A Case Report and Literature Review

Daptomycin is a canonical antibiotic used very commonly in practice for its bactericidal activity against Gram-positive bacteria, including vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, bone infections, skin and soft tissue infections, meningitis, urinary tract infections, and endocarditis. Although daptomycin in conventional doses is usually well tolerated, it is paramount to be aware of the possible adverse effects. Daptomycin is reported to cause an elevation in creatine kinase levels, although frank rhabdomyolysis is rare. An even more infrequent occurrence is the simultaneous development of acute kidney injury and drug-induced liver injury with rhabdomyolysis. Daptomycin and rifampin combination are used for synergistic bactericidal action against MRSA. Still, data on the efficacy and safety of the combination is limited due to a lack of extensive studies. Herein, we present a clinical case of septic arthritis of a prosthetic knee, which resulted in bacteremia caused by methicillin-resistant Staphylococcus aureus (MRSA) and subsequently led to infective endocarditis of the aortic valve. The patient was treated with a combination of daptomycin and rifampin, complicated by the development of rhabdomyolysis, acute kidney injury, and drug-induced liver injury. This case highlights the significance of timely recognizing adverse drug effects and identifying risk factors to ensure successful patient outcomes.

Characterization of plasma daptomycin in patients with serum highly glycated albumin and obesity

PURPOSE

Plasma daptomycin has not been fully characterized in diabetic and obese patients. This study aimed to evaluate the associations of plasma daptomycin with glycation of serum albumin and obesity.

METHODS

Infectious patients (n = 70) receiving intravenous daptomycin were enrolled. The plasma concentration of total and free daptomycin were determined using liquid chromatograph-tandem mass spectrometer. The associations of the plasma concentrations of daptomycin with clinical factors including serum albumin fractionations and physical status (obese including overweight, body mass index ≥ 25.0) were investigated. Daptomycin doses were adjusted using total body-weight.

RESULTS

The serum albumin level was positively and negatively correlated with the plasma concentration of total daptomycin and its free fraction proportion, respectively. The serum non-glycated albumin was negatively correlated with the free fraction proportion. The dose-normalized plasma concentration of total daptomycin was higher in the obese patients than in non-obese patients when the body-weight was corrected with total and adjusted values. For the dose adjustment with lean body-weight, no difference was observed in the dose-normalized plasma concentration of total daptomycin between the physical statuses. For each body-weight correction method, physical status did not affect the dose-normalized plasma concentration of free daptomycin.

CONCLUSION

The glycation of serum albumin and obesity did not associate with dose-normalized plasma free daptomycin. In obese patients, daptomycin dosage adjustment with total body-weight and adjusted body-weight may lead to an apparent excessive exposure resulting in overdosage compared to lean body-weight.

Incidence of elevated creatine phosphokinase between daptomycin alone and concomitant daptomycin and statins: a systematic review and meta-analysis

AIM

The present systematic review and meta-analysis evaluated the incidence of elevated creatine phosphokinase (CPK) levels between daptomycin alone and concomitant daptomycin and statin use.

METHODS

We searched the PubMed, Web of Sciences, Cochrane Library, and ClinicalTrials.gov databases. We analysed the incidence of elevated CPK between daptomycin alone and concomitant daptomycin and statins among studies defining CPK elevation as levels ≥ the upper limit of normal (ULN) or ≥ 5 times ULN. We also analysed the incidence of rhabdomyolysis between the groups. We then calculated the odds ratios (ORs) and 95% confidence intervals (CIs) based on the included studies.

RESULTS

Comparing CPK elevation defined as CPK levels ≥ ULN, a significantly higher incidence of CPK elevation was observed with concomitant daptomycin and statin use than with daptomycin alone (OR=2.55, 95% CI 1.78-3.64, p<0.00001, I² =0%). Likewise, when CPK elevation was defined as CPK levels ≥ 5 times ULN, a significantly higher incidence of CPK elevation was detected with concomitant daptomycin and statin use than with daptomycin alone (OR = 1.89, 95% CI 1.06-3.35, p=0.03, I² =48%). The incidence of rhabdomyolysis was significantly higher following concomitant daptomycin and statin use than with daptomycin alone (OR = 11.60, 95% CI 1.81-74.37, p=0.01, I² =0%).

CONCLUSIONS

The combined use of daptomycin and statins were significant risk factors for the incidence of CPK elevation defined as levels ≥ ULN or ≥ 5 times ULN and rhabdomyolysis.

Factors affecting creatine phosphokinase elevation during daptomycin therapy using a combination of machine learning and conventional methods

AIMS

Musculoskeletal toxicity is a typical side effect of daptomycin (DAP). However, the risk factors have not been well established. Here, we aimed to identify independent factors affecting DAP-induced musculoskeletal toxicity using a combination of machine learning and conventional statistical methods.

METHODS

A population-based, retrospective, observational cohort study was conducted using the Japanese electronic medical record database. Patients who received DAP between October 2011 and December 2020 were enrolled. Two definitions of musculoskeletal toxicity were employed: (1) elevation of creatine phosphokinase (CPK) value more than twice from baseline and >200 IU/L, and (2) >1000 IU/L. First, multiple logistic regression analyses (a conventional statistical method) were performed to identify independent factors affecting CPK elevation. Then, decision tree analyses, a machine learning method, were performed to detect combinations of factors that change CPK elevation risk.

RESULTS

Of the 2970 patients who received DAP, 706 were included. Elevation of CPK values >200 IU/L and >1000 IU/L occurred in 83 (11.8%) and 17 (2.41%) patients, respectively. In multiple logistic regression analysis, baseline CPK value and concomitant use of hydrophobic statins were commonly extracted as independent factors affecting each CPK elevation, but concomitant use of hydrophilic statins was not. In decision tree analysis, patients who received hydrophobic statins and had high baseline CPK values were classified into the high-risk group.

CONCLUSION

Our novel approach revealed new risk factors for CPK elevation. Our findings suggest that high-risk patients require frequent CPK monitoring.

High-Dose Daptomycin and Clinical Applications

OBJECTIVE

To evaluate evidence for high-dose daptomycin (doses ≥ 8 mg/kg/d).

DATA SOURCES

A PubMed/MEDLINE literature search was performed (January 2000 to December 2020) using the search terms daptomycin, high dose, and dosing. Review article references and society guidelines were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Clinical trials, observational studies, retrospective studies, meta-analyses, and systematic reviews reporting on high-dose daptomycin were included.

DATA SYNTHESIS

Experimentally, daptomycin outperforms other antimicrobials for high inoculum and biofilm-associated infections. Clinically, high-dose daptomycin is supported as salvage and first-line therapy for endocarditis and bacteremia, primarily when caused by methicillin-resistant Staphylococcus aureus (when vancomycin minimum inhibitory concentration is >1 mg/L) and Enterococcus. High-dose daptomycin appears effective for osteomyelitis and central nervous system infections, although comparative studies are lacking. High dosing in renal replacement therapy requires considering clearance modality to achieve exposures like normal renal function. Weight-based dosing in obesity draws concern for elevated exposures, although high doses have not been evaluated kinetically in obesity. Some data show benefits of high doses in overweight populations. Burn patients clear daptomycin more rapidly, and high doses may only achieve drug exposures similar to standard doses (6 mg/kg).

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review analyzes the efficacy and safety of high-dose daptomycin in serious gram-positive infections. Discussion of specific infectious etiologies and patient populations should encourage clinicians to evaluate their daptomycin dosing standards.

CONCLUSIONS

The efficacy of high-dose daptomycin and limited safety concerns encourage clinicians to consider high-dose daptomycin more liberally in severe gram-positive infections.

Clinical Pharmacokinetics of Daptomycin

Due to the low level of resistance observed with daptomycin, this antibiotic has an important place in the treatment of severe Gram-positive infections. It is the first-in-class of the group of calcium-dependent, membrane-binding lipopeptides, and is a cyclic peptide constituted of 13 amino acids and an n-decanoyl fatty acid chain. The antibacterial action of daptomycin requires its complexation with calcium. Daptomycin is not absorbed from the gastrointestinal tract and needs to be administered parenterally. The distribution of daptomycin is limited (volume of distribution of 0.1 L/kg in healthy volunteers) due to its negative charge at physiological pH and its high binding to plasma proteins (about 90%). Its elimination is mainly renal, with about 50% of the dose excreted unchanged in the urine, justifying dosage adjustment for patients with renal insufficiency. The pharmacokinetics of daptomycin are altered under certain pathophysiological conditions, resulting in high interindividual variability. As a result, therapeutic drug monitoring of daptomycin may be of interest for certain patients, such as intensive care unit patients, patients with renal or hepatic insufficiency, dialysis patients, obese patients, or children. A target for the ratio of the area under the curve to the minimum inhibitory concentration > 666 is usually recommended for clinical efficacy, whereas in order to limit the risk of undesirable muscular effects the residual concentration should not exceed 24.3 mg/L.

Daptomycin in combination with rosuvastatin induced blood creatine phosphokinase elevation

We present the case of a 73-year-old male patient who was hospitalised with infective endocarditis, and report an elevation in his blood creatine phosphokinase (CPK) after receiving daptomycin and rosuvastatin therapy concomitantly. His previous home-scheduled medications included apixaban, ivabradine, metformin, rosuvastatin 20 mg, ginkgo biloba and trimetazidine, and he continued to receive these medications at the hospital. After three sets of blood cultures were taken, empirical treatment was started with vancomycin and gentamicin. On the eighth day of treatment, daptomycin and ampicillin-sulbactam were initiated due to ampicillin-resistant Enterococcus faecalis growth in the patient's blood culture. Daptomycin and rosuvastatin were discontinued on the 23rd day of treatment because of blood CPK elevation (2416 U/L) and linezolid was started instead of daptomycin. Six days after discontinuation of daptomycin and rosuvastatin, the CPK concentrations returned to normal range.

Observational retrospective single-centre study in Japan to assess the clinical significance of serum daptomycin levels in creatinine phosphokinase elevation

WHAT IS KNOWN AND OBJECTIVE

Daptomycin-induced creatinine phosphokinase (CPK) elevation is reported to be associated with its trough level (C_trough ; breakpoint of 24.3 μg/mL). However, even with high-dose treatment (ie, > 8 mg/kg), the safety of daptomycin treatment is widely demonstrated with low or no significant incidence of CPK elevation or other adverse effects, despite the possibility of C_trough above 24.3 μg/mL. Therefore, we questioned the clinical significance of C_trough levels of 24.3 μg/mL. In this study, we retrospectively evaluated the significance of C_trough in the clinical setting, in addition to completing a retrospective safety assessment of daptomycin utilizing electronic health records.

METHODS

Patients who had received daptomycin treatment for > 4 days from July 2011 to June 2015 were enrolled. Serum daptomycin levels, including C_trough and peak (C_peak ), were measured by high-performance liquid chromatography equipped with a photodiode array. To evaluate the safety, patients' characteristics and relevant laboratory test values were reviewed retrospectively using an electronic medical record system.

RESULTS AND DISCUSSION

A total of 52 therapeutic cases for 46 patients were identified; of these, C_trough and C_peak levels were measured in 27 and 28 cases, respectively, and 6 patients received multiple courses of daptomycin treatment. The median age of the 52 patients was 68 years (range: 19-88 years), and 14 patients initially had an estimated creatinine clearance of less than 30 mL/min. Seven cases indicated a C_trough of above 24.3 μg/mL; however, none of these presented CPK elevation, which meets with the study definition for abnormality. Furthermore, of the two patients with abnormal CPK elevations, only one patient had a measured C_trough (of 10.9 μg/mL). Their CPK abnormalities were temporal and did not result in treatment discontinuation. The other four patients discontinued daptomycin treatment due to suspicions of adverse effects. Of the discontinued patients, two had measured C_trough levels; these were 8.6 and 8.1 μg/mL. All patients with abnormal CPK elevation or treatment discontinuation exhibited C_trough levels lower than 24.3 μg/mL. In this study, two patients receiving high-dose daptomycin (ie, 9.4 and 10.0 mg/kg) had observed C_trough levels similar to patients who received doses of daptomycin < 9 mg/kg.

WHAT IS NEW AND CONCLUSIONS

The safety of daptomycin treatment was suggested in this study. C_trough level of 24.3 μg/mL was not suggested as a significant clinical index for the incidence of CPK elevation, adverse effects or treatment discontinuation. Thus, acceptable tolerability towards higher C_trough levels than 24.3 μg/mL was also suggested, though further studies are required. On the other hand, low levels of daptomycin in blood were unexpectedly observed in two cases, despite the high-dose treatments. Accordingly, the monitoring of serum daptomycin levels may also be useful to assess cases in which subtherapeutic levels were achieved.

Daptomycin dosing in obese patients: analysis of the use of adjusted body weight versus actual body weight

Background

Food and Drug Administration-approved daptomycin dosing uses actual body weight, despite limited dosing information for obese patients. Studies report alterations in daptomycin pharmacokinetics and creatine phosphokinase elevations associated with higher weight-based doses required for obese patients. Limited information regarding clinical outcomes with alternative daptomycin dosing strategies in obesity exists.

Objective

This study evaluates equivalency of clinical and safety outcomes in obese patients with daptomycin dosed on adjusted body weight versus a historical cohort using actual body weight.

Methods

This retrospective, single center study compared equivalency of outcomes with two one-sided tests in patients with body mass index ⩾30 kg/m² who received daptomycin dosed on actual body weight versus adjusted body weight. The primary outcome was clinical failure. Secondary outcomes included 90-day readmission and 90-day mortality. A combined safety endpoint included creatine phosphokinase elevation, patient-reported myopathy, and rhabdomyolysis.

Results

A total of 667 patients were screened for inclusion; 101 patients were analyzed with 50 in the actual body weight cohort and 51 in the adjusted body weight cohort. The two regimens were statistically equivalent for clinical failure (2% actual body weight versus 4% adjusted body weight; p < 0.001 for equivalency). The two regimens were also statistically equivalent for 90-day mortality (6% actual body weight versus 4% adjusted body weight; p = 0.0014 for equivalency). Limitations include single center, retrospective design, and sample size. Daptomycin dosing intensified throughout the study period.

Conclusion

The two daptomycin dosing cohorts were statistically equivalent for both clinical failure and 90-day mortality. More data are needed to assess outcomes with higher (⩾8 mg/kg/day) daptomycin doses in this patient population.

Effect of Statin Coadministration on the Risk of Daptomycin-Associated Myopathy

Background

Daptomycin-associated myopathy has been identified in 2%-14% of patients, and rhabdomyolysis is a known adverse effect. Although risk factors for daptomycin-associated myopathy are poorly defined, creatine phosphokinase (CPK) monitoring and temporary discontinuation of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or "statins," has been recommended.

Methods

We conducted a single-center, retrospective, matched case-control risk factor analysis in adult and pediatric patients from 2004 to 2015. Patients in whom myopathy (defined as CPK values above the upper limit of normal) developed during daptomycin treatment were matched 1:1 to no-myopathy controls with at least the same duration of therapy. Risk factors independently associated with myopathy were determined using multivariable conditional logistic regression. Secondary analysis was performed in patients with rhabdomyolysis, defined as CPK values ≥10 times the upper limit of normal.

Results

Of 3042 patients reviewed, 128 (4.2%) were identified as having daptomycin-associated myopathy, 25 (0.8%) of whom had rhabdomyolysis; 121 (95%) of the 128 were adults, and the mean duration of therapy before CPK elevation was 16.7 days (range, 1-58 days). In multivariate analysis, deep abscess treatment (odds ratio, 2.80; P = .03), antihistamine coadministration (3.50; P = .03), and statin coadministration (2.60; P = .03) were independent risk factors for myopathy. Obesity (odds ratio, 3.28; P = .03) and statin coadministration (4.67; P = .03) were found to be independent risk factors for rhabdomyolysis, and older age was associated with reduced risk (0.97; P = .05).

Conclusions

Statin coadministration with daptomycin was independently associated with myopathy and rhabdomyolysis. This is the first study to provide strong evidence supporting this association. During coadministration, we recommend twice-weekly CPK monitoring and consideration of withholding statins.

Safety of high-dose daptomycin in patients with severe renal impairment

Background

Treatment options are limited for infections due to multidrug-resistant Gram-positive pathogens. Daptomycin is a lipopeptide antibiotic with concentration-dependent killing characteristic and dose-dependent post-antibiotic effect. To achieve optimized pharma-codynamic effect, some experts advocated using a high dose of daptomycin (≥9 mg/kg) for severe infections. However, the safety of high-dose therapy in patients with renal impairment remains unknown. This study was aimed to evaluate the safety of daptomycin in patients with severe renal impairment.

Methods

This was a retrospective study performed by reviewing electronic medical records. Patients with severe renal impairment who were treated with daptomycin in a tertiary teaching hospital between January 1, 2013, and June 30, 2016, were included for evaluation. The incidence rates of creatine kinase (CK) elevation between high-dose (≥9 mg/kg) and standard-dose (<9 mg/kg) groups were compared.

Results

Overall, 164 patients met the inclusion criteria, and 114 (69.5%) of them were on renal replacement therapy. Vancomycin-resistant enterococci were the most common pathogens (61.3%) of the patients with documented pathogens. The treatment success rate was 51.6% in the 91 patients with bacteremia. The average dose of daptomycin was 8.0±2.3 mg/kg, and 37 (22.6%) patients received ≥9 mg/kg. CK levels were followed in 108 (65.9%) patients. Significantly higher incidence of CK elevation was found in the high-dose group compared with that in the standard-dose group (10.8% vs 1.6%, P<0.05). Moreover, patients with elevated CK received a higher dose of daptomycin than those without (9.3±1.2 vs 7.9±2.3 mg/kg, P<0.05). There was no significant difference in the rate of CK elevation between patients treated with different dosing frequency or with the concurrent use of statins, fibrate, or colchicine.

Conclusions

In patients with severe renal impairment, high-dose (≥9 mg/kg) daptomycin therapy may result in a significantly higher incidence of CK elevation. More frequent CK monitoring is warranted to avoid potential harm in this population.

Development of a pharmacist-driven protocol for automatic medication dosage adjustments in obese patients

PURPOSE

A hospital protocol utilizing automatic dosage adjustments and pharmacist consultations to optimize the use of certain medications in obese patients is described.

SUMMARY

After conducting a literature search focused on medication dosing in obese patients, pharmacists at a large community hospital developed a list of commonly ordered medications appropriate for inclusion in a pharmacy-driven institutional protocol for automatic medication dosage adjustment in adult patients with obesity. Evidence-based recommendations on initial dosing of eight antimicrobials and two anticoagulant agents according to weight and renal function were formulated. Under the protocol, pharmacists receive electronic alerts regarding protocol-eligible patients during initial order verification and automatically adjust medication dosages as appropriate. For patients prescribed anticoagulants at specified dosage levels, clinical pharmacists consult with prescribers to help ensure safe and effective initial and ongoing therapy. Multidisciplinary educational initiatives were conducted prior to protocol implementation. During two designated three-week postimplementation data collection periods, pharmacists received a total of 372 protocol-eligible medication orders. Pharmacists adjusted a total of 149 dosages and verified an additional 183 dosages consistent with the protocol as originally ordered. Clinical pharmacy consults were completed for 10-15% of patients, with laboratory monitoring ordered in 25-30% of those cases (all patients were found to have appropriate test values). There have been no documented adverse drug reactions in patients whose medication dosages were adjusted per protocol.

CONCLUSION

Pharmacists implemented weight- and renal function-based dosage adjustments for obese patients in 40% of evaluated protocol-eligible cases to achieve 89% compliance with the protocol. Heparin and cefazolin were the medications most likely to require obesity-related dosage adjustments.

Interaction of obesity and infections

There is evidence that certain infections may induce obesity. Obese persons may also have more severe infections and have compromised response to therapies. The objective of this study is to review the available literature identifying infections that potentially contribute to greater body mass index (BMI) and differential responses of overweight and obese persons to infections. A systematic literature review of human studies examining associations between infections and weight gain, differential susceptibility, severity, and response to prevention and treatment of infection according to BMI status (January 1980-July 2014) was conducted. Three hundred and forty-three studies were eligible for inclusion. Evidence indicated that viral infection by human adenovirus Ad36 and antibiotic eradication of Helicobacter pylori were followed by weight gain. People who were overweight or obese had higher susceptibility to developing post-surgical infections, H1N1 influenza and periodontal disease. More severe infections tended to be present in people with a larger BMI. People with a higher BMI had a reduced response to vaccinations and antimicrobial drugs. Higher doses of antibiotics were more effective in obese patients. Infections may influence BMI, and BMI status may influence response to certain infections, as well as to preventive and treatment measures. These observations have potential clinical implications.

Musculoskeletal safety outcomes of patients receiving daptomycin with HMG-CoA reductase inhibitors

Daptomycin, a cyclic lipopeptide antibiotic, and 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) are commonly administered in the inpatient setting and are associated with creatine phosphokinase (CPK) elevations, myalgias, and muscle weakness. Safety data for coadministration of daptomycin with statins are limited. To determine the safety of coadministration of daptomycin with statin therapy, a multicenter, retrospective, observational study was performed at 13 institutions in the Southeastern United States. Forty-nine adult patients receiving statins concurrently with daptomycin were compared with 171 patients receiving daptomycin without statin therapy. Detailed information, including treatment indication and duration, infecting pathogen, baseline and subsequent CPK levels, and presence of myalgias or muscle complaints, was collected. Myalgias were noted in 3/49 (6.1%) patients receiving combination therapy compared with 5/171 (2.9%) of patients receiving daptomycin alone (P = 0.38). CPK elevations of >1,000 U/liter occurred in 5/49 (10.2%) patients receiving combination therapy compared to 9/171 (5.3%) patients receiving daptomycin alone (P = 0.32). Two of five patients experiencing CPK elevations of >1,000 U/liter in the combination group had symptoms of myopathy. Three patients (6.1%) discontinued therapy due to CPK elevations with concurrent myalgias in the combination group versus 6 patients (3.5%) in the daptomycin-alone group (P = 0.42). CPK levels and myalgias reversed upon discontinuation of daptomycin therapy. Overall musculoskeletal toxicity was numerically higher in the combination group but this result was not statistically significant. Further prospective study is warranted in a larger population.

Impact of hospital guideline for weight-based antimicrobial dosing in morbidly obese adults and comprehensive literature review

WHAT IS KNOWN AND OBJECTIVE

Obesity is a significant burden on the healthcare system in the United States, and determining the appropriate antimicrobial dosing regimen in morbidly obese patients is challenging. Morbidly obese patients have documented differences in pharmacokinetic and pharmacodynamic properties compared to normal-weight patients, which impact antibiotic efficacy and toxicity. The Food and Drug Administration does not recognize obesity as a special population and does not require pharmaceutical companies to perform studies specific to obese patients. However, there are an increasing number of post-approval studies in obese patients, and this manuscript reviews available clinical and pharmacokinetic literature regarding weight-based antimicrobial agents. Additionally, we describe a single-centre approach to optimize dosing in morbidly obese patients.

METHODS

A comprehensive literature search was performed on 15 weight-based antimicrobials in the setting of obesity: acyclovir, aminoglycosides, amphotericin B, cidofovir, colistimethate, daptomycin, flucytosine, foscarnet, ganciclovir, quinupristin/dalfopristin, trimethoprim/sulfamethoxazole, vancomycin and voriconazole. A weight-based antimicrobial dosing guideline for morbidly obese patients was developed. An analysis of guideline compliance and cost analysis were performed following guideline implementation.

RESULTS AND DISCUSSION

This review describes the pharmacokinetic changes that occur in obese patients, including increased volume of distribution, altered hepatic metabolism, renal excretion and changes in protein binding. The majority of weight-based antimicrobials result in increased serum concentrations in morbidly obese patients compared to normal-weight patients when the calculated dose is based on actual body weight.

WHAT IS NEW AND CONCLUSION

This review demonstrates different antibiotic pharmacokinetic properties are altered in obese patients that could impact efficacy and toxicity. A single-centre guideline for weight-based antimicrobial dosing in obesity was developed and provides recommendations for using ideal body weight, adjusted body weight or actual body weight when calculating antimicrobial doses. However, more research is needed to better elucidate optimal dosing of weight-based antimicrobials in obesity, with particular focus on efficacy and toxicity.

Daptomycin dosing strategies in patients receiving thrice-weekly intermittent hemodialysis

OBJECTIVE

To determine the optimal dosing regimen of daptomycin in patients receiving thrice-weekly hemodialysis.

DATA SOURCES

Literature was accessed via PubMed using the terms daptomycin and hemodialysis through July 2013. Reference citations from publications identified were reviewed.

STUDY SELECTION AND DATA EXTRACTION

English language articles meeting the search criteria were evaluated. Studies were included if they addressed either thrice-weekly or intradialytic daptomycin administration.

DATA SYNTHESIS

Daptomycin is approved for the treatment of bloodstream infections due to methicillin-resistant Staphylococcus aureus and other Gram-positive organisms. Rapid bactericidal activity and limited potential for drug interactions make daptomycin an attractive agent. However, the daptomycin prescribing information recommends dosing every 48 hours in patients receiving hemodialysis, which results in dyssynchrony of dosing and dialysis sessions every other week. Studies evaluating a dosing regimen of daptomycin thrice weekly, coinciding with dialysis, indicate that pharmacokinetic and pharmacodynamic parameters are appropriate for therapeutic success. However, to maintain adequate serum drug concentrations throughout the 72-hour interdialytic period, an additional 50% of the dose should be provided to account for the longer interval. Intradialytic dosing, with the administration of daptomycin infusion beginning during the final 30 minutes of dialysis, may also require a dose increase. Limited clinical outcomes data have been reported, but no significant safety concerns have been identified.

CONCLUSIONS

Administration of daptomycin doses thrice weekly on hemodialysis days appears to be both safe and reasonable. Doses should be increased preceding the 72-hour interdialytic period or if daptomycin is infused during dialysis.

Daptomycin-induced rhabdomyolysis and acute liver injury

Daptomycin use is a known cause of rhabdomyolysis; its role in liver injury is less certain. We report a case of daptomycin-induced rhabdomyolysis with liver injury. This report indicates a role for liver function monitoring while receiving daptomycin, as well as the importance of promptly considering drug toxicities in acute and emergency care settings.