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  1. Abdul-Aziz MH, Lipman J, Roberts JA
    Curr. Opin. Infect. Dis., 2017 Apr;30(2):231-239.
    PMID: 28030371 DOI: 10.1097/QCO.0000000000000348
    PURPOSE OF REVIEW: Nosocomial pneumonia caused by multidrug-resistant pathogens is increasing in the ICU, and these infections are negatively associated with patient outcomes. Optimization of antibiotic dosing has been suggested as a key intervention to improve clinical outcomes in patients with nosocomial pneumonia. This review describes the recent pharmacokinetic/pharmacodynamic data relevant to antibiotic dosing for nosocomial pneumonia caused by multidrug-resistant pathogens.

    RECENT FINDINGS: Optimal antibiotic treatment is challenging in critically ill patients with nosocomial pneumonia; most dosing guidelines do not consider the altered physiology and illness severity associated with severe lung infections. Antibiotic dosing can be guided by plasma drug concentrations, which do not reflect the concentrations at the site of infection. The application of aggressive dosing regimens, in accordance to the antibiotic's pharmacokinetic/pharmacodynamic characteristics, may be required to ensure rapid and effective drug exposure in infected lung tissues.

    SUMMARY: Conventional antibiotic dosing increases the likelihood of therapeutic failure in critically ill patients with nosocomial pneumonia. Alternative dosing strategies, which exploit the pharmacokinetic/pharmacodynamic properties of an antibiotic, should be strongly considered to ensure optimal antibiotic exposure and better therapeutic outcomes in these patients.

  2. Sulaiman H, Abdul-Aziz MH, Roberts JA
    Semin Respir Crit Care Med, 2017 06;38(3):271-286.
    PMID: 28578552 DOI: 10.1055/s-0037-1602716
    Hospital-acquired pneumonia and ventilator-associated pneumonia continue to cause significant morbidity and mortality. With increasing rates of antimicrobial resistance, the importance of optimizing antibiotic treatment is key to maximize treatment outcomes. This is especially important in critically ill patients in intensive care units, in whom the infection is usually caused by less susceptible organisms. In addition, the marked physiological changes that can occur in these patients can cause serious changes in antibiotic pharmacokinetics which in turn alter the attainment of therapeutic drug exposures. This article reviews the various aspects of the pharmacokinetic changes that can occur in the critically ill patients, the barriers to achieving therapeutic drug exposures in pneumonia for systemically delivered antibiotics, the optimization for commonly used antibiotics in hospital- and ventilator-associated pneumonia, the agents that should be avoided in the treatment regimen, as well as the use of adjunctive therapy in the form of nebulized antibiotics.
  3. Sulaiman H, Roberts JA, Abdul-Aziz MH
    Farm Hosp, 2022 Mar 26;46(3):182-190.
    PMID: 36183212
    Optimal antibiotic therapy for critically ill patients can be complicated bythe altered physiology associated with critical illness. Antibiotic pharmacokineticsand exposures can be altered driven by the underlying critical illnessand medical interventions that critically ill patients receive in the intensivecare unit. Furthermore, pathogens that are usually isolated in the intensivecare unit are commonly less susceptible and "resistant" to common antibiotics.Indeed, antibiotic dosing that does not consider these unique differenceswill likely fail leading to poor clinical outcomes and the emergenceof antibiotic resistance in the intensive care unit. The aims of this narrativereview were to describe the pharmacokinetics of beta-lactam antibiotics incritically ill patients, to highlight pharmacokinetic/pharmacodynamic targetsfor both non-critically ill and critically ill patients, and to discuss importantstrategies that can be undertaken to optimize beta-lactam antibiotic dosingfor critically ill patients in the intensive care unit.
  4. Cheng V, Abdul-Aziz MH, Roberts JA, Shekar K
    Expert Opin Drug Metab Toxicol, 2019 Feb;15(2):103-112.
    PMID: 30582435 DOI: 10.1080/17425255.2019.1563596
    INTRODUCTION: One major challenge to achieving optimal patient outcome in extracorporeal membrane oxygenation (ECMO) is the development of effective dosing strategies in this critically ill patient population. Suboptimal drug dosing impacts on patient outcome as patients on ECMO often require reversal of the underlying pathology with effective pharmacotherapy in order to be liberated of the life-support device. Areas covered: This article provides a concise review of the effective use of antibiotics, analgesics, and sedative by characterizing the specific changes in PK secondary to the introduction of the ECMO support. We also discuss the barriers to achieving optimal pharmacotherapy in patients on ECMO and also the current and potential research that can be undertaken to address these clinical challenges. Expert opinion: Decreased bioavailability due to sequestration of drugs in the ECMO circuit and ECMO induced PK alterations are both significant barriers to optimal drug dosing. Evidence-based drug choices may minimize sequestration in the circuit and would enable safety and efficacy to be maintained. More work to characterize ECMO related pharmacodynamic alterations such as effects of ECMO on hepatic cytochrome system are still needed. Novel techniques to increase target site concentrations should also be explored.
  5. Cheng V, Abdul-Aziz MH, Roberts JA, Shekar K
    J Thorac Dis, 2018 Mar;10(Suppl 5):S629-S641.
    PMID: 29732181 DOI: 10.21037/jtd.2017.09.154
    Optimal pharmacological management during extracorporeal membrane oxygenation (ECMO) involves more than administering drugs to reverse underlying disease. ECMO is a complex therapy that should be administered in a goal-directed manner to achieve therapeutic endpoints that allow reversal of disease and ECMO wean, minimisation of complications (treatment of complications when they do occur), early interruption of sedation and rehabilitation, maximising patient comfort and minimising risks of delirium. ECMO can alter both the pharmacokinetics (PK) and pharmacodynamics (PD) of administered drugs and our understanding of these alterations is still evolving. Based on available data it appears that modern ECMO circuitry probably has a less significant impact on PK when compared with critical illness itself. However, these findings need further confirmation in clinical population PK studies and such studies are underway. The altered PD associated with ECMO is less understood and more research is indicated. Until robust dosing guidelines become available, clinicians will have to rely on the principles of drug dosing in critically ill and known PK alterations induced by ECMO itself. This article summarises the PK alterations and makes preliminary recommendations on possible dosing approaches.
  6. Koulenti D, Song A, Ellingboe A, Abdul-Aziz MH, Harris P, Gavey E, et al.
    Int J Antimicrob Agents, 2019 Mar;53(3):211-224.
    PMID: 30394301 DOI: 10.1016/j.ijantimicag.2018.10.011
    The spread of multidrug-resistant bacteria is an ever-growing concern, particularly among Gram-negative bacteria because of their intrinsic resistance and how quickly they acquire and spread new resistance mechanisms. Treating infections caused by Gram-negative bacteria is a challenge for medical practitioners and increases patient mortality and cost of care globally. This vulnerability, along with strategies to tackle antimicrobial resistance development, prompts the development of new antibiotic agents and exploration of alternative treatment options. This article summarises the new antibiotics that have recently been approved for Gram-negative bacterial infections, looks down the pipeline at promising agents currently in phase I, II, or III clinical trials, and introduces new alternative avenues that show potential in combating multidrug-resistant Gram-negative bacteria.
  7. Osthoff M, Siegemund M, Balestra G, Abdul-Aziz MH, Roberts JA
    Swiss Med Wkly, 2016;146:w14368.
    PMID: 27731492 DOI: 10.4414/smw.2016.14368
    Prolonged infusion of β-lactam antibiotics as either extended (over at least 2 hours) or continuous infusion is increasingly applied in intensive care units around the world in an attempt to optimise treatment with this most commonly used class of antibiotics, whose effectiveness is challenged by increasing resistance rates. The pharmacokinetics of β-lactam antibiotics in critically ill patients is profoundly altered secondary to an increased volume of distribution and the presence of altered renal function, including augmented renal clearance. This may lead to a significant decrease in plasma concentrations of β-lactam antibiotics. As a consequence, low pharmacokinetic/pharmacodynamic (PK/PD) target attainment, which is described as the percentage of time that the free drug concentration is maintained above the minimal inhibitory concentration (MIC) of the causative organism (fT>MIC), has been documented for β-lactam treatment in these patients when using standard intermittent bolus dosing, even for the most conservative target (50% fT>MIC). Prolonged infusion of β-lactams has consistently been shown to improve PK/PD target attainment, particularly in patients with severe infections. However, evidence regarding relevant patient outcomes is still limited. Whereas previous observational studies have suggested a clinical benefit of prolonged infusion, results from two recent randomised controlled trials of continuous infusion versus intermittent bolus administration of β-lactams are conflicting. In particular, the larger, double-blind placebo-controlled randomised controlled trial including 443 patients did not demonstrate any difference in clinical outcomes. We believe that a personalised approach is required to truly optimise β-lactam treatment in critically ill patients. This may include therapeutic drug monitoring with real-time adaptive feedback, rapid MIC determination and the use of antibiotic dosing software tools that incorporate patient parameters, dosing history, drug concentration and site of infection. Universal administration of β-lactam antibiotics as prolonged infusion, even if supported by therapeutic drug monitoring, is not yet ready for "prime time", as evidence for its clinical benefit is modest. There is a need for prospective randomised controlled trials that assess patient-centred outcomes (e.g. mortality) of a personalised approach in selected critically ill patients including prolonged infusion of β-lactams compared with the current standard of care.
  8. Mazlan MZ, Zainal Abidin H, Wan Hassan WMN, Nik Mohamad NA, Salmuna ZN, Ibrahim K, et al.
    IDCases, 2020;22:e01001.
    PMID: 33204633 DOI: 10.1016/j.idcr.2020.e01001
    We present a case study of a 26-year-old morbidly obese man with a three-day history of right leg pain and swelling. The swelling was associated with low grade fever. He was alert and conscious upon presentation to the hospital. His physical examination showed gross swelling of the entire right lower limb with no systemic manifestations. There was no discharge and bullae from the swelling area of the leg. He had high blood sugar and was newly diagnosed with type 2 diabetes mellitus. He was diagnosed with necrotizing fasciitis. An intravenous imipenem-cilastatin 500 mg every 6 h together with clindamycin 900 mg every 8 h was started empirically. Extensive wound debridement was performed. The swab culture obtained intraoperatively grew Pseudomonas aeruginosa. He required an above knee amputation due to worsening infection despite wound debridement. Post-operatively, he developed acute kidney injury with severe metabolic acidosis, which required daily hemodialysis. However, the patient deteriorated due to septic shock with multi-organ failure, resulting in his death.
  9. Rhodes NJ, Liu J, O'Donnell JN, Dulhunty JM, Abdul-Aziz MH, Berko PY, et al.
    Crit Care Med, 2018 02;46(2):236-243.
    PMID: 29116995 DOI: 10.1097/CCM.0000000000002836
    OBJECTIVE: Piperacillin-tazobactam is a commonly used antibiotic in critically ill patients; however, controversy exists as to whether mortality in serious infections can be decreased through administration by prolonged infusion compared with intermittent infusion. The purpose of this systematic review and meta-analysis was to describe the impact of prolonged infusion piperacillin-tazobactam schemes on clinical endpoints in severely ill patients.

    DESIGN: We conducted a systematic literature review and meta-analysis searching MEDLINE, Cumulative Index to Nursing and Allied Health Literature, and the Cochrane Library from inception to April 1, 2017, for studies.

    INTERVENTIONS: Mortality rates were compared between severely ill patients receiving piperacillin-tazobactam via prolonged infusion or intermittent infusion. Included studies must have reported severity of illness scores, which were transformed into average study-level mortality probabilities.

    MEASUREMENTS AND MAIN RESULTS: Two investigators independently screened titles, abstracts, and full texts of studies meeting inclusion criteria for this systematic review and meta-analysis. Variables included author name, publication year, study design, demographics, total daily dose(s), average estimated creatinine clearance, type of prolonged infusion, prevalence of combination therapy, severity of illness scores, infectious sources, all-cause mortality, clinical cure, microbiological cure, and hospital and ICU length of stay. The review identified 18 studies including 3,401 patients who received piperacillin-tazobactam, 56.7% via prolonged infusion. Across all studies, the majority of patients had an identified primary infectious source. Receipt of prolonged infusion was associated with a 1.46-fold lower odds of mortality (95% CI, 1.20-1.77) in the pooled analysis. Patients receiving prolonged infusion had a 1.77-fold higher odds of clinical cure (95% CI, 1.24-2.54) and a 1.22-fold higher odds of microbiological cure (95% CI, 0.84-1.77). Subanalyses were conducted according to high (≥ 20%) and low (< 20%) average study-level mortality probabilities. In studies reporting higher mortality probabilities, effect sizes were variable but similar to the pooled results.

    CONCLUSIONS: Receipt of prolonged infusion of piperacillin-tazobactam was associated with reduced mortality and improved clinical cure rates across diverse cohorts of severely ill patients.

  10. Abdul-Aziz MH, Abd Rahman AN, Mat-Nor MB, Sulaiman H, Wallis SC, Lipman J, et al.
    Antimicrob Agents Chemother, 2016 01;60(1):206-14.
    PMID: 26482304 DOI: 10.1128/AAC.01543-15
    Doripenem has been recently introduced in Malaysia and is used for severe infections in the intensive care unit. However, limited data currently exist to guide optimal dosing in this scenario. We aimed to describe the population pharmacokinetics of doripenem in Malaysian critically ill patients with sepsis and use Monte Carlo dosing simulations to develop clinically relevant dosing guidelines for these patients. In this pharmacokinetic study, 12 critically ill adult patients with sepsis receiving 500 mg of doripenem every 8 h as a 1-hour infusion were enrolled. Serial blood samples were collected on 2 different days, and population pharmacokinetic analysis was performed using a nonlinear mixed-effects modeling approach. A two-compartment linear model with between-subject and between-occasion variability on clearance was adequate in describing the data. The typical volume of distribution and clearance of doripenem in this cohort were 0.47 liters/kg and 0.14 liters/kg/h, respectively. Doripenem clearance was significantly influenced by patients' creatinine clearance (CL(CR)), such that a 30-ml/min increase in the estimated CL(CR) would increase doripenem CL by 52%. Monte Carlo dosing simulations suggested that, for pathogens with a MIC of 8 mg/liter, a dose of 1,000 mg every 8 h as a 4-h infusion is optimal for patients with a CL(CR) of 30 to 100 ml/min, while a dose of 2,000 mg every 8 h as a 4-h infusion is best for patients manifesting a CL(CR) of >100 ml/min. Findings from this study suggest that, for doripenem usage in Malaysian critically ill patients, an alternative dosing approach may be meritorious, particularly when multidrug resistance pathogens are involved.
  11. Roberts JA, Abdul-Aziz MH, Davis JS, Dulhunty JM, Cotta MO, Myburgh J, et al.
    Am J Respir Crit Care Med, 2016 Sep 15;194(6):681-91.
    PMID: 26974879 DOI: 10.1164/rccm.201601-0024OC
    RATIONALE: Optimization of β-lactam antibiotic dosing for critically ill patients is an intervention that may improve outcomes in severe sepsis.

    OBJECTIVES: In this individual patient data meta-analysis of critically ill patients with severe sepsis, we aimed to compare clinical outcomes of those treated with continuous versus intermittent infusion of β-lactam antibiotics.

    METHODS: We identified relevant randomized controlled trials comparing continuous versus intermittent infusion of β-lactam antibiotics in critically ill patients with severe sepsis. We assessed the quality of the studies according to four criteria. We combined individual patient data from studies and assessed data integrity for common baseline demographics and study endpoints, including hospital mortality censored at 30 days and clinical cure. We then determined the pooled estimates of effect and investigated factors associated with hospital mortality in multivariable analysis.

    MEASUREMENTS AND MAIN RESULTS: We identified three randomized controlled trials in which researchers recruited a total of 632 patients with severe sepsis. The two groups were well balanced in terms of age, sex, and illness severity. The rates of hospital mortality and clinical cure for the continuous versus intermittent infusion groups were 19.6% versus 26.3% (relative risk, 0.74; 95% confidence interval, 0.56-1.00; P = 0.045) and 55.4% versus 46.3% (relative risk, 1.20; 95% confidence interval, 1.03-1.40; P = 0.021), respectively. In a multivariable model, intermittent β-lactam administration, higher Acute Physiology and Chronic Health Evaluation II score, use of renal replacement therapy, and infection by nonfermenting gram-negative bacilli were significantly associated with hospital mortality. Continuous β-lactam administration was not independently associated with clinical cure.

    CONCLUSIONS: Compared with intermittent dosing, administration of β-lactam antibiotics by continuous infusion in critically ill patients with severe sepsis is associated with decreased hospital mortality.

  12. Abdul-Aziz MH, Sulaiman H, Mat-Nor MB, Rai V, Wong KK, Hasan MS, et al.
    Intensive Care Med, 2016 Oct;42(10):1535-1545.
    PMID: 26754759 DOI: 10.1007/s00134-015-4188-0
    PURPOSE: This study aims to determine if continuous infusion (CI) is associated with better clinical and pharmacokinetic/pharmacodynamic (PK/PD) outcomes compared to intermittent bolus (IB) dosing in critically ill patients with severe sepsis.

    METHODS: This was a two-centre randomised controlled trial of CI versus IB dosing of beta-lactam antibiotics, which enrolled critically ill participants with severe sepsis who were not on renal replacement therapy (RRT). The primary outcome was clinical cure at 14 days after antibiotic cessation. Secondary outcomes were PK/PD target attainment, ICU-free days and ventilator-free days at day 28 post-randomisation, 14- and 30-day survival, and time to white cell count normalisation.

    RESULTS: A total of 140 participants were enrolled with 70 participants each allocated to CI and IB dosing. CI participants had higher clinical cure rates (56 versus 34 %, p = 0.011) and higher median ventilator-free days (22 versus 14 days, p MIC than the IB arm on day 1 (97 versus 70 %, p 

  13. Rozali MA, Abd Rahman NS, Sulaiman H, Abd Rahman AN, Atiya N, Wan Mat WR, et al.
    J Pharm Bioallied Sci, 2020 Nov;12(Suppl 2):S804-S809.
    PMID: 33828380 DOI: 10.4103/jpbs.JPBS_266_19
    Introduction: Approach to managing infection in the intensive care unit (ICU) often varies between institutions and not many readily adapt to available local guidelines despite it was constructed to suite local clinical scenario. Malaysia already has two published guidelines on managing infection in the ICU but data on its compliance are largely unknown.

    Objectives: A cross-sectional survey was carried out and sent to a total of 868 specialists working primarily in the ICU. The aim of this study was to explore knowledge, perception, and the antibiotic prescribing practice among specialists and advanced trainees in Malaysian ICU.

    Materials and Methods: A cross-sectional survey was used, consisted of three sections: knowledge, perception, and antibiotic prescribing practice in ICU. Three case vignettes on hospital-acquired pneumonia (HAP), infected necrotizing pancreatitis (INP), and catheter-related bloodstream infection (CRBSI) were used to explore antibiotic prescribing practice.

    Results: A total of 868 eligible subjects were approached with 104 responded to the survey. Three hundred eighty-nine antibiotics were chosen from seven different classes in the case vignettes. All respondents acknowledged the importance of pharmacokinetic/pharmacodynamic (PK/PD) in antibiotic optimization and majority (97.2%) perceived that current dosing is inadequate to achieve optimal PK/PD target in ICU patients. Majority (85.6%) believed that antibiotic dose should be streamlined to the organisms' minimum inhibitory concentration (MIC). In terms of knowledge, only 64.4% provided the correct correlations between antibiotics and their respective PK/PD targets. Compliance rates in terms of antibiotic choices were at 79.8%, 77.8%, and 27.9% for HAI, INP, and CRBSI, respectively.

    Conclusion: Malaysian physicians are receptive to use PK/PD approach to optimize antibiotic dosing in ICU patients. Nonetheless, there are still gaps in the knowledge of antibiotic PK/PD as well as its application in the critically ill, especially for β-lactams.

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