Intravitreal Aflibercept for Neovascular Age-Related Macular Degeneration Beyond One Year of Treatment: AZURE, a Randomized Trial of Treat-and-Extend vs. Fixed Dosing.

INTRODUCTION: AZURE was a 76-week, randomized, open-label, parallel-group, phase IIIb noninferiority study comparing the efficacy and safety of intravitreal aflibercept (IVT-AFL) in a treat-and-extend (T&E) regimen with fixed dosing in patients with neovascular age-related macular degeneration (nAMD) previously receiving IVT-AFL for ≥ 1 year. METHODS: Patients were aged ≥ 51 years and had completed ≥ 1 year of IVT-AFL treatment prior to enrollment (IVT-AFL once per month [- 1 or + 2 weeks] for 3 months followed by IVT-AFL every 2 months [6-12 weeks]). Patients were randomly assigned (1:1) to receive IVT-AFL 2 mg in either a T&E (minimum treatment interval of 8 weeks with no upper limit, adjusted according to functional and anatomic outcomes, as assessed by the investigator; n = 168), or a fixed dosing regimen (treatment every 8 weeks [± 3 days]; n = 168). The primary endpoint was best-corrected visual acuity (BCVA) change from baseline to week (W) 52. The key secondary endpoint was the proportion of patients maintaining vision (< 15-letter loss) at W52. RESULTS: The full analysis set comprised 332 patients (T&E: n = 165; fixed dosing: n = 167). Mean BCVA change (baseline to W52) was - 0.3 ± 7.5 vs. - 0.5 ± 8.4 letters (T&E vs. fixed dosing; least-squares mean difference [95% CI]: 0.22 [- 1.51 to 1.96] letters; P < 0.0001 for noninferiority test [5-letter margin]). From baseline to W52, 95.2% (T&E) and 94.0% (fixed dosing) of patients maintained vision. Mean central subfield thickness change from baseline to W52 was - 24 ± 55 (T&E) and - 33 ± 47 (fixed dosing) µm. Last treatment interval to W76 was ≥ 12 weeks for 37.0% of T&E patients. No new safety signals were identified. CONCLUSION: IVT-AFL T&E can achieve similar functional and anatomic outcomes to fixed dosing every 8 weeks over 52 weeks in patients with nAMD who have completed ≥ 1 year of treatment, while reducing treatment burden. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02540954.

Bridging Fixed Dose to Body Weight-based Regimen of Adalimumab in Paediatric Ulcerative Colitis Using a Pharmacometric Modelling Approach: Case Study with the Phase 3 ENVISION I Trial.

BACKGROUND AND AIMS: The Phase 3 study ENVISION I demonstrated efficacy and safety of adalimumab in paediatric patients with moderate to severe ulcerative colitis. The protocol-specified high-dose adalimumab regimen was numerically more efficacious than the standard-dose regimen. The objective of this work was to bridge a fixed-dosing regimen to the protocol-specified high-induction/high-maintenance, body weight-based dosing regimen studied in ENVISION I, using a pharmacometrics modelling and simulation approach. METHODS: A stepwise strategy was implemented, including developing an adalimumab paediatric population pharmacokinetic model; using this model to determine a fixed-dosing regimen in paediatric ulcerative colitis patients which achieves similar concentrations to those observed in ENVISION I patients; determining adalimumab exposure-response relationship using population pharmacokinetic/pharmacodynamic model and data from ENVISION I; simulating clinical remission rate in paediatric ulcerative colitis patients using the Markov exposure-response model and the dosing regimen determined to provide similar efficacy to that observed in ENVISION I. RESULTS: Both developed population pharmacokinetic and pharmacokinetic/pharmacodynamic models adequately described the observed data. Adalimumab exposure was identified as a significant predictor of clinical remission at Week 8 based on logistic regression [p <0.01]. Simulated efficacy suggested that the fixed-dosing regimen performs similarly to the more efficacious dosing regimen used in ENVISION I, by providing comparable clinical remission per Partial Mayo Score response rates over time. No relationship between adalimumab exposure and adverse events was identified. CONCLUSIONS: The population pharmacokinetic/pharmacodynamic model supports the appropriateness of the use of the fixed-dosing regimen in the paediatric ulcerative colitis population.

Brolucizumab 12- and 16-Week Fixed Dosing Potential in Neovascular AMD: A post hoc Evaluation of Data from the HAWK and HARRIER Trials.

INTRODUCTION: This post hoc analysis applies a fixed dosing stratification approach to patient-level brolucizumab data from the phase III HAWK and HARRIER trials to determine the proportion of patients who would have been assigned to fixed dosing regimens with treatment intervals of 8, 12, or 16 weeks (q8w, q12w, or q16w) based on the presence/absence of disease activity (DA) following the loading phase. The analysis also simulates central subfield thickness (CSFT) data to estimate the anatomical outcomes if the patients had been thus assigned. Of note, the limitations of this analysis include the post hoc nature of the work and the inability to directly compare HAWK and HARRIER with TENAYA and LUCERNE due to the differences in design. DESIGN: This study was a post hoc modelling analysis of patient-level data. METHODS: Using patient-level data from HAWK and HARRIER, patients (n = 730) were allocated to a fixed q16w, q12w, or q8w regimen based on assessment of DA at weeks 16 and 20. Two definitions of DA were used: DA 1, based on a phase II study of faricimab, and DA 2, a definition derived from common clinical consideration including visual acuity and anatomical changes. CSFT simulations were performed using a pharmacokinetic/pharmacodynamic model describing CSFT response to anti-VEGF treatment. Outcome measures were modelled patient allocation to fixed regimens and mean CSFT reduction. RESULTS: Using DA definitions 1 and 2, respectively, 78% and 76% of patients in the brolucizumab arm were allocated to a greater than or equal to q12w regimen, and 56% and 52% were allocated to a q16w regimen. Mean reduction in CSFT was similar between the two study drugs with both DA definition assumptions. CONCLUSIONS: This analysis demonstrates the potential durability of action and effectiveness of brolucizumab.

Warfarin dosing strategies evolution and its progress in the era of precision medicine, a narrative review.

Background For decades, vitamin K antagonists and specifically warfarin, have been the sole agents used orally to manage thromboembolic conditions, including stroke and venous thromboembolism (VTE). Several factors lead to warfarin dose variability, including genetic and non-genetic factors which made warfarin management challenging especially at the initiation phase. To overcome the challenges with warfarin dosing at initiation, strategies other than conventional or fixed dosing were introduced and explored. Aim In this narrative review, we aim to discuss and critique the different dosing strategies for warfarin at initiation with more focus on genotype-guided warfarin dosing and the most recent supporting evidence for and against its use. Method Medline database was searched from 1965 to July 2021. Articles addressing different warfarin dosing methods were screened for inclusion. Results A number of methods exist for warfarin initiation. Studies comparing different dosing methods for initiation yielded conflicting outcomes due to differences in study design, population studied, comparator, and outcomes measured. Conclusions Looking at the big picture, the use of genetic dosing for warfarin initiation can lead to better outcomes. Whether these better outcomes are clinically or economically beneficial remains controversial.

Evaluation of fixed versus variable dosing of 4-factor prothrombin complex concentrate for emergent warfarin reversal.

STUDY OBJECTIVE: This study compares the safety and efficacy of a fixed dose of 4-factor prothrombin complex concentrate (4FPCC) to the FDA-approved variable dosing for reversal of warfarin-induced anticoagulation. METHODS: This was a single-center, prospective, open-label, randomized controlled trial with subjects randomized to 4FPCC at a fixed dose of 1500 IU or the FDA-approved variable dosing regimen. The primary efficacy outcome (reversal success) was defined as a post-intervention international normalized ratio (INR) of less than or equal to 1.5. Given that 4FPCC is the standard of care for reversal of warfarin-induced anticoagulation an active-controlled approach was employed with the two dosing regimens compared based on efficacy, cost, and safety outcomes. RESULTS: 71 subjects (34 in the fixed dose group and 37 in the variable dose group) completed the study. There were no significant differences in age, gender, weight, initial INR, or indication for 4FPCC administration between the two treatment groups. Reversal success in the fixed-dose group was 61.8%, while in the variable dose group reversal success was 89.2%. Reversal success in the fixed-dose group was significantly lower than the rate of reversal success in the variable dose group (27.4% lower, p = 0.011). CONCLUSION: The results of this study provide evidence that fixed dosing results in lower reversal success rates as compared to variable dosing of 4FPCC for warfarin-induced anticoagulation.

Fixed Dose of Cemiplimab in Patients with Advanced Malignancies Based on Population Pharmacokinetic Analysis.

INTRODUCTION: This study outlined cemiplimab intravenous (IV) dosing strategy to move from body weight (BW)-based 3 mg/kg every-2-week (Q2W) dosing in first-in-human study (study 1423; NCT02383212) to fixed 350 mg every-3-week (Q3W) dosing, utilizing population pharmacokinetics (PopPK) modeling and simulations, and supported by a limited dataset from a phase 2 study (study 1540; NCT02760498). METHODS: Cemiplimab concentration data from a total of 505 patients were pooled from study 1423 in advanced malignancies and study 1540 in advanced cutaneous squamous cell carcinoma (CSCC). All patients received weight-based cemiplimab dose (1, 3, 10 mg/kg Q2W or 3 mg/kg Q3W) except 4% who received 200 mg Q2W. A linear two-compartment PopPK model incorporating covariates that improved goodness-of-fit statistics was developed to compare cemiplimab exposure at 350 mg Q3W versus 3 mg/kg Q2W. Upon availability, observed cemiplimab concentration at 350 mg Q3W in study 1540 was then compared with the simulated values. RESULTS: Post hoc estimates of cemiplimab exposure and variability (505 patients; weight range 30.9-156 kg; median 76.1 kg) at steady state were found to be similar at 350 mg Q3W and 3 mg/kg Q2W. Effect of BW on cemiplimab exposure was described by exposure versus BW plots and at extreme BW. Overlay of individual observed cemiplimab concentrations in 51 patients with metastatic CSCC on simulated concentration-time profiles in 2000 patients at 350 mg Q3W confirmed cemiplimab exposure similarity and demonstrated the robustness of dose optimization based on PopPK modeling and simulations. CONCLUSIONS: Cemiplimab 350 mg Q3W is being further investigated in multiple indications.

One-year outcomes of fixed-dosing Aflibercept therapy for pre treated and naive polypoidal choroidal vasculopathy patient.

BACKGROUND: Polypoidal choroidal vasculopathy (PCV) is a type of age-related macular degeneration that can cause permanent vision loss. The purpose of this paper was to report the one-year outcomes of fixed-dosing aflibercept therapy for the treatment of PCV. METHODS: This was a prospective, single-arm, interventional case series study of 25 PCV patients; 12 pre-treated and 13 treatment-naïve patients. The patients were treated and monitored for 12 months. Each patient was administered with an aflibercept (2.0 mg) injection every month for the first 3 months (the loading phase), and thereafter, once every 2 months. At every follow-up visit, best-corrected visual acuity (BCVA) test, fundus examination, and optical coherence tomography for measuring the central subfield macular thickness (CSMT) were performed. Fluorescein and indocyanine green angiography were conducted at baseline and at 4 and 12 months. RESULTS: After 12 months of aflibercept therapy, the mean BCVA of the patients significantly improved from 65.48 letters at baseline to 69.91 letters (p=0.001), and the CSMT significantly decreased from 406.92 um at baseline to 276.12 um (p< 0.001). Additionally, ten patients (40%) showed complete polyp regression. The treatment-naïve patients showed a statistically significant improvement in BCVA from 66.58 letters at baseline to 76.36 letters at 12 months, and a significant decrease in CSMT, from 462 to 243 um. In the pre-treated group, there was no change in BCVA (64.46 letters), and the decrease in CSMT from 356.08 to 303.69 um was not statistically significant. CONCLUSIONS: The fixed-dosing aflibercept regimen is effective for treating patients with PCV and is more effective in treatment-naïve patients than in pre-treated patients. TRIAL REGISTRATION: Clinical Research Information Service (CRiS), Republic of Korea. Identifer: KCT0005798, Registered: Jan 20, 2021. Retrospectively registered, URL: https://cris.nih.go.kr/cris/en/search/search_result_st01.jsp?seq=18546.

Optimal dosing for psilocybin pharmacotherapy: Considering weight-adjusted and fixed dosing approaches.

BACKGROUND: Growing evidence suggests psilocybin, a naturally occurring psychedelic, is a safe and promising pharmacotherapy for treatment of mood and substance use disorders when administered as part of a structured intervention. In most trials to date, psilocybin dose has been administered on a weight-adjusted basis rather than the more convenient procedure of administering a fixed dose. AIMS: The present post hoc analyses sought to determine whether the subjective effects of psilocybin are affected by body weight when psilocybin is administered on a weight-adjusted basis and when psilocybin is administered as a fixed dose. METHODS: We analyzed acute subjective drug effects (mystical, challenging, and intensity) associated with therapeutic outcomes from ten previous studies (total N = 288) in which psilocybin was administered in the range 20 to 30 mg/70 kg (inclusive). Separate multivariate regression analyses examined the relationships between demographic variables including body weight and subjective effects in participants receiving 20 mg/70 kg (n = 120), participants receiving 30 mg/70 kg (n = 182), and participants whose weight-adjusted dose was about 25 mg (to approximate the fixed dose that is currently being evaluated in registration trials for major depressive disorder) (n = 103). RESULTS: In the 20 mg/70 kg and 30 mg/70 kg weight-adjusted groups, and in the fixed dose group, no significant associations were found between subjective effects and demographic variables including body weight or sex. Across a wide range of body weights (49 to 113 kg) the present results showed no evidence that body weight affected subjective effects of psilocybin. CONCLUSIONS: These results suggest that the convenience and lower cost of administering psilocybin as a fixed dose outweigh any potential advantage of weight-adjusted dosing.

A cost analysis study of the implementation of fixed-dosing of monoclonal antibodies in the Netherlands Cancer Institute.

Background There is a strong rationale for fixed-dosing of monoclonal antibodies in oncology. Although fixed-dosing of recently introduced monoclonal antibodies is well accepted, the rationale is also applicable for other monoclonal antibodies that already have been used for years, but are still body-size-based dosed in many hospitals. In the Netherlands Cancer Institute, Antoni van Leeuwenhoek (NKI-AVL), fixed-dosing has been implemented now for all monoclonal antibodies and, therefore, this site offers an ideal opportunity for a cost analysis study. Objective To investigate the financial impact of switching to fixed-dosing in the NKI-AVL. Setting The NKI-AVL. Method Information on the preparations of monoclonal antibodies was collected from August 2017 to February 2020. We compared the number of vials needed during preparation for fixed-dosing and body-size -based dosing strategies. The economic impact was calculated for 2 scenarios: scenario 1 assumed clustering of all preparations per day and scenario 2 assumed no clustering of preparations. Main outcome measure Number of saved vials and the correlating savings in health care costs. Results The implementation of fixed-dosing resulted in a substantial reduction in vials used for almost all monoclonal antibodies. The economic savings were calculated to be €0,8 and €3,1 million per year for scenario 1 and 2, respectively. Conclusion Fixed-dosing resulted in substantial savings in health care costs.

Follow up survey for implementation of fixed-dosing of monoclonal antibodies.

Background Similar to the earlier anti-cancer therapies, monoclonal antibodies were introduced in bodysize-based schedules, despite the fact that body size only modestly effects the distribution, elimination and efficacy of monoclonal antibodies. Fixed-dosing of nivolumab and pembrolizumab has recently been approved by the European Medicines Agency. Objective To investigate the implementation of fixed-dosing of nivolumab, pembrolizumab and other monoclonal antibodies in the treatment of cancer. Method An online questionnaire was distributed among Dutch hospitals in January 2019. Results The majority of the hospitals (> 60%) responded, with a good representation of the characteristics of the hospitals in the Netherlands. Most hospitals which prescribe nivolumab and/or pembrolizumab have introduced fixed-dose-based schedules. However, the dosing of the other monoclonal antibodies was still based on body size. Conclusion Fixed-dosebased schedules of nivolumab and pembrolizumab have been rapidly implemented in most Dutch hospitals after approval of the European Medicines Agency. Despite emerging evidence which supports fixed-dose-based schedules for almost all the other monoclonal antibodies, its implementation stays behind. To increase the acceptance of fixed-dose-based schedules of monoclonal antibodies in the guidelines, additional studies may be needed, which focus on evaluating exposure, activity and cost effectiveness with the attempt to uncover the exact savings in costs for patient care.

No benefit from flexible titration above minimum licensed dose in prescribing antidepressants for major depression: systematic review.

BACKGROUND: In fixed-dose antidepressant trials, the lower range of the licensed dose achieves the optimal balance between efficacy and tolerability. Whether flexible upward titration while side-effects permit provides additional benefits is unknown. METHODS: We did a systematic review of placebo-controlled randomized trials that examined selective serotonin reuptake inhibitors (SSRIs), venlafaxine or mirtazapine in the acute treatment of major depression. Our primary outcome was response, defined as 50% or greater reduction in depression severity. Secondary outcomes included drop-outs due to adverse effects and drop-outs for any reason. We conducted random-effects meta-analyses to calculate the ratios of odds ratios (RORs) between trials comparing the flexible dose titrating above the minimum licensed dose against placebo and those comparing the fixed minimum licensed dose against placebo. RESULTS: We included 123 published and unpublished randomized controlled trials (29 420 participants). There was no evidence supporting efficacy of the flexible dosing over the fixed low dose of SSRIs (ROR 0.96, 95% CI: 0.73 to 1.25), venlafaxine (1.24, 0.96 to 1.60) or mirtazapine (0.77, 0.33 to 1.78). No important differences were noted for tolerability or for any subgroup analyses except the superior efficacy of venlafaxine flexible dosing between 75 and 150 mg over the fixed 75 mg (1.30, 1.02 to 1.65). CONCLUSION: There was no evidence to support added value in terms of efficacy, tolerability or acceptability of flexibly titrating up the dosage over the minimum licensed dose of SSRIs or mirtazapine. For venlafaxine, increased efficacy can be expected by flexibly titrating up to 150 mg.

Model-Based Population Pharmacokinetic Analysis of Nivolumab in Chinese Patients With Previously Treated Advanced Solid Tumors, Including Non-Small Cell Lung Cancer.

Nivolumab is the first anti-programmed death-1 agent approved in China for treatment of locally advanced or metastatic non-small cell lung cancer (NSCLC). Here, we characterize the population pharmacokinetics (PPK) of nivolumab monotherapy in Chinese patients with previously treated advanced/recurrent solid tumors, including NSCLC and nasopharyngeal cancer (NPC), using data from 2 predominantly Chinese (CheckMate 077 and 078), and 5 global (MDX1106-01, CA209-003, and CheckMate 017, 057, and 063) studies. The PPK model was developed by reestimating parameters of a prior global population model with Chinese patient data. Model reestimates showed nivolumab pharmacokinetics (PK) to be linear and dose proportional. Race did not have a clinically meaningful effect on nivolumab clearance. Body weight, Asian race, sex, and performance status had significant effects on clearance. Baseline clearance was 9% lower in the Asian versus the global population but not considered clinically relevant. Change in time-varying clearance and predicted nivolumab exposures with 3 mg/kg every 2 weeks (Q2W) were similar in Chinese, non-Chinese Asian, and non-Asian patients. In Chinese patients, the predicted nivolumab exposure with a 240-mg Q2W regimen was ∼25% higher than with 3 mg/kg Q2W, but ∼62% lower than that of a previously evaluated, well-tolerated regimen of 10 mg/kg Q2W (global population). Differences in nivolumab baseline clearance and exposures between patients with NPC and NSCLC were not clinically meaningful (<20%). Overall, PPK analysis demonstrated that nivolumab was not sensitive to race when evaluated in Chinese and non-Asian patients and exhibited similar PK in NSCLC and NPC.

Optimizing the dose in patients treated with imatinib as first line treatment for gastrointestinal stromal tumours: A cost-effectiveness study.

AIMS: Patients with metastatic gastrointestinal stromal tumours (GIST) are treated in first line with the oral tyrosine kinase inhibitor, imatinib, until progressive disease. With this fixed dosing regimen, only approximately 40% of patients reach adequate plasma levels within the therapeutic index. Therapeutic drug monitoring (TDM) is a solution to reach plasma levels within the therapeutic index. However, introducing TDM will also increase costs, due to prolonged imatinib use and laboratory costs. The aim of this study was to evaluate the cost-effectiveness of TDM in patients with metastatic/unresectable GIST treated with imatinib as a first line treatment, compared with fixed dosing. METHODS: A survival model was created to simulate progression, mortality and treatment costs over a 5-year time horizon, comparing fixed dosing vs TDM-guided dosing. The outcomes measured were treatments costs, life-years and quality-adjusted life-years. RESULTS: Total costs over the 5-year time horizon were estimated to be €106 994.85 and €150 477.08 for fixed dosing vs TDM-guided dosing, respectively. A quality-adjusted life year gain of 0.74 (95% confidence interval 0.66-0.90) was estimated with TDM-guided dosing compared to fixed dosing. An average incremental cost-effectiveness ratio of €58 785.70 per quality-adjusted life year gained was found, mainly caused by longer use and higher dosages of imatinib. CONCLUSION: Based on the currently available data, this analysis suggests that TDM-guided dosing may be a cost-effective intervention for patients with metastatic/unresectable GIST treated with imatinib which will be improved when imatinib losses its patency.

Fixed dosing of intravenous tocilizumab in rheumatoid arthritis. Results from a population pharmacokinetic analysis.

AIMS: Intravenous tocilizumab is currently dosed on body weight, although a weak correlation between body weight and clearance has been described. The aim of the study was to assess the current dosing strategy and provide a scientific rational for dosing using a modelling and simulation approach. METHODS: Serum concentrations and covariates were obtained from intravenous tocilizumab treated subjects at a dose of 4, 6 or 8 mg every 28 days. A population pharmacokinetic analysis was performed using nonlinear mixed effects modelling. The final model was used to simulate tocilizumab exposure to assess a dosing strategy based on body weight or fixed dosing, using as target a cumulative area under the curve at 24 weeks of treatment above 100 × 103  µg h ml-1 . RESULTS: A one-compartment disposition model with parallel linear and nonlinear elimination best described the concentration-time data. The typical population mean values for clearance, apparent volume of distribution, maximum elimination rate and Michaelis-Menten constant were 0.0104 l h-1 , 4.83 l, 0.239 mg h-1 and 4.22 µg ml-1 , respectively. Interindividual variability was included for clearance (17.0%) and volume of distribution (30.8%). Significant covariates for clearance were patient body weight and C-reactive protein serum levels. An estimated exponent for body weight of 0.360 confirms the weak relationship with tocilizumab clearance. Simulations demonstrate that patients with lower weights are at risk of underdosing if the weight-based dosing approach is used. However, fixed-dosing provides a more consistent drug exposure regardless of weight category. CONCLUSIONS: Our study provides evidence to support fixed dosing of intravenous tocilizumab in rheumatoid arthritis patients since it reduces variability in tocilizumab exposure among weight categories compared to the current weight-based dosing approach.

Fixed Dosing of Monoclonal Antibodies in Oncology.

Most monoclonal antibodies in oncology are administered in body-size-based dosing schedules. This is believed to correct for variability in both drug distribution and elimination between patients. However, monoclonal antibodies typically distribute to the blood plasma and extracellular fluids only, which increase less than proportionally with the increase in body weight. Elimination takes place via proteolytic catabolism, a nonspecific immunoglobulin G elimination pathway, and intracellular degradation after binding to the target. The latter is the primary route of elimination and is related to target expression levels rather than body size. Taken together, the minor effects of body size on distribution and elimination of monoclonal antibodies and their usually wide therapeutic window do not support body-size-based dosing. We evaluated effects of body weight on volume of distribution and clearance of monoclonal antibodies in oncology and show that a fixed dose for most of these drugs is justified based on pharmacokinetics. A survey of the savings after fixed dosing of monoclonal antibodies at our hospital showed that fixed dosing can reduce costs of health care, especially when pooling of preparations is not possible (which is often the case in smaller hospitals). In conclusion, based on pharmacokinetic parameters of monoclonal antibodies, there is a rationale for fixed dosing of these drugs in oncology. Therefore, we believe that fixed dosing is justified and can improve efficiency of the compounding. Moreover, drug spillage can be reduced and medication errors may become less likely. IMPLICATIONS FOR PRACTICE: The currently available knowledge of elimination of monoclonal antibodies combined with the publicly available data from clinical trials and extensive population pharmacokinetic (PopPK) modeling justifies fixed dosing. Interpatient variation in exposure is comparable after body weight and fixed dosing and most monoclonal antibodies show relatively flat dose-response relationships. For monoclonal antibodies, this results in wide therapeutic windows and no reduced clinical efficacy after fixed dosing. Therefore, we believe that fixed dosing at a well-selected dose can increase medication safety and help in reduction of costs of health care without the loss of efficacy or safety margins.

Review of current evidence available for guiding optimal Enoxaparin prophylactic dosing strategies in obese patients-Actual Weight-based vs Fixed.

BACKGROUND: The current debate over the optimal Enoxaparin prophylactic dosing strategies in obese patients centre around whether it should be based on the actual weight of the patient (i.e. weight-based), or at an artificially fixed amount, as it is the case in Australia (40mg daily). The vast majority of the evidence available today is laboratory-based, measuring serum Antifactor-Xa activities as a marker for physiological response. AIM: The aim of the parent study is to compare the clinical outcomes for obese patients who received fixed doses of enoxaparin compared to those who received weight-based doses within the licensed dosage recommendations. This review was conducted to examine whether a gap in knowledge exists in relation to dosing obese patients with enoxaparin as VTE prophylaxis after hospital admission to aid in development of the parent study concept. METHOD: Databases such as Medline, EBSCOhost, ProQuest were interrogated using combinations of words such as "enoxaparin", AND "dosing strategy", AND "obese/obesity" AND "prophylaxis". Only eleven out of 14 primary studies which were considered to be sufficiently similar in methodology and anticipated outcomes were reviewed and analysed. RESULTS: Pooled data from the eleven studies suggested that weight-based or higher-than-fixed dosing had a 36.2% higher success rate than fixed dosing, and was more likely to achieve the desired serum Anti-Xa activity levels (52.2% and 16% respectively). The rate of failure to achieve this is significantly lower in the weight-based groups (13.3%) than in fixed-dose groups (18.5%). These eleven studies reviewed included 601 patients in total. CONCLUSION: There is insufficient evidence to support or negate the current enoxaparin health outcomes in obese and very obese patients due to the lack of post-discharge follow-up from hospitals. Further research is required to compare long-term outcomes after fixed and weight-based dosing of enoxaparin. The optimal dose of enoxaparin per kilogram of body weight for prophylaxis remains to be determined.