Displaying publications 21 - 34 of 34 in total

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  1. Mazlan-Kepli W, Macisaac RL, Walters M, Bath PMW, Dawson J, VISTA Collaborators
    Br J Clin Pharmacol, 2017 Sep;83(9):2045-2055.
    PMID: 28299795 DOI: 10.1111/bcp.13290
    AIMS: Antiplatelet drugs are often discontinued early after ischaemic stroke, either because of poor compliance, complications or withdrawal of care. It is unclear whether this places patients at increased risk of recurrence. We explored the association between cardiovascular event rate and persistence with prescribed antiplatelet drugs.

    METHODS: We used a matched case-control design using the Virtual International Stroke Trials Archive (VISTA). Cases were patients who had an acute coronary syndrome, recurrent stroke or transient ischaemic attack within 90 days post-stroke and were matched for age ± 10 years and sex with up to four controls. Antiplatelet use was categorized as persistent (used for >3 days and continued up to day 90), early cessation (used antiplatelet <3 days) or stopped/interrupted users (used for >3 days but stopped prior to day 90). These categories were compared in cases and controls using a conditional logistic regression model that adjusted for potential confounders.

    RESULTS: A total of 970 patients were included, of whom 194 were cases and 776 were matched controls. At 90 days, 10 cases (5.2%) and 58 controls (7.5%) stopped/interrupted their antiplatelet. The risk of cardiovascular event was not different in stopped/interrupted users (adjusted odds ratio 0.70, 95% confidence interval 0.33, 1.48; P = 0.352) and early cessations (adjusted odds ratio 1.04, 95% confidence interval 0.62, 1.74; P = 0.876) when compared to persistent users.

    CONCLUSION: We found no increased risk in patients who stopped and interrupted antiplatelets early after stroke but the study was limited by a small sample size and further research is needed.

  2. Lee SWH, Mak VSL, Tang YW
    Br J Clin Pharmacol, 2019 12;85(12):2668-2688.
    PMID: 31465121 DOI: 10.1111/bcp.14101
    AIMS: Pharmacists have been contributing to the care of residents in nursing homes and play a significant role in ensuring quality use of medicine. However, the changing role of pharmacist in nursing homes and their impact on residents is relatively unknown.

    METHODS: Six electronic databases were searched from inception until November 2018 for articles published in English examining the services offered by pharmacists in nursing homes. Studies were included if it examined the impact of interventions by pharmacists to improve the quality use of medicine in nursing homes.

    RESULTS: Fifty-two studies (30 376 residents) were included in the current review. Thirteen studies were randomised controlled studies, while the remainder were either pre-post, retrospective or case-control studies where pharmacists provided services such as clinical medication review in collaboration with other healthcare professionals as well as staff education. Pooled analysis found that pharmacist-led services reduced the mean number of falls (-0.50; 95% confidence interval: -0.79 to -0.21) among residents in nursing homes. Mixed results were noted on the impact of pharmacists' services on mortality, hospitalisation and admission rates among residents. The potential financial savings of such services have not been formally evaluated by any studies thus far. The strength of evidence was moderate for the outcomes of mortality and number of fallers.

    CONCLUSION: Pharmacists contribute substantially to patient care in nursing homes, ensuring quality use of medication, resulting in reduced fall rates. Further studies with rigorous design are needed to measure the impact of pharmacist services on the economic benefits and other patient health outcomes.

  3. Tan CSS, Lee SWH
    Br J Clin Pharmacol, 2021 02;87(2):352-374.
    PMID: 32478963 DOI: 10.1111/bcp.14404
    AIMS: To present an updated overview on the safety of concurrent use of food, herbal or dietary supplement and warfarin.

    METHODS: A systematic literature review was performed on 5 databases from inception up to 31 December 2019. These interactions were classified depending on the likelihood of interaction and supporting evidences.

    RESULTS: A total of 149 articles describing 78 herbs, food or dietary supplements were reported to interact with warfarin. These reports described potentiation with 45 (57.7%) herbs, food or dietary supplements while 23 (29.5%) reported inhibition and 10 (12.8%) reported limited impact on warfarin pharmacokinetics and pharmacodynamics. Twenty unique herb and dietary supplements also reported to result in minor bleeding events, such as purpura and gum bleeding as well as major events such as intracranial bleeding that led to death.

    CONCLUSION: While most food, herbs and supplements can be safely taken in moderation, healthcare professionals should be aware of the increased risk of bleeding when taking several food and herbs. These include Chinese wolfberry, chamomile tea, cannabis, cranberry, chitosan, green tea, Ginkgo biloba, ginger, spinach, St. John's Wort, sushi and smoking tobacco. Patients should be counselled to continue to seek advice from their healthcare professionals when starting any new herbs, food or supplement.

  4. Lee JL, Mohd Saffian S, Makmor-Bakry M, Islahudin F, Alias H, Noh LM, et al.
    Br J Clin Pharmacol, 2021 07;87(7):2956-2966.
    PMID: 33377197 DOI: 10.1111/bcp.14712
    AIMS: There is considerable interpatient variability in the pharmacokinetics (PK) of intravenous immunoglobulin G (IVIG), causing difficulty in optimizing individual dosage regimen. This study aims to estimate the population PK parameters of IVIG and to investigate the impact of genetic polymorphism of the FcRn gene and clinical variability on the PK of IVIG in patients with predominantly antibody deficiencies.

    METHODS: Patients were recruited from four hospitals. Clinical data were recorded and blood samples were taken for PK and genetic studies. Population PK parameters were estimated by nonlinear mixed-effects modelling in Monolix®. Models were evaluated using the difference in objective function value, goodness-of-fit plots, visual predictive check and bootstrap analysis. Monte Carlo simulation was conducted to evaluate different dosing regimens for IVIG.

    RESULTS: A total of 30 blood samples were analysed from 10 patients. The immunoglobulin G concentration data were best described by a one-compartment model with linear elimination. The final model included both volume of distribution (Vd) and clearance (CL) based on patient's individual weight. Goodness-of-fit plots indicated that the model fit the data adequately, with minor model mis-specification. Genetic polymorphism of the FcRn gene and the presence of bronchiectasis did not affect the PK of IVIG. Simulation showed that 3-4-weekly dosing intervals were sufficient to maintain IgG levels of 5 g L-1 , with more frequent intervals needed to achieve higher trough levels.

    CONCLUSIONS: Body weight significantly affects the PK parameters of IVIG. Genetic and other clinical factors investigated did not affect the disposition of IVIG.

  5. Kirubakaran R, Hennig S, Maslen B, Day RO, Carland JE, Stocker SL
    Br J Clin Pharmacol, 2021 Sep 23.
    PMID: 34558092 DOI: 10.1111/bcp.15091
    BACKGROUND AND AIM: Identification of the most appropriate population pharmacokinetic model-based Bayesian estimation is required prior to its implementation in routine clinical practice to inform tacrolimus dosing decisions. This study aimed to determine the predictive performances of relevant population pharmacokinetic models of tacrolimus developed from various solid organ transplant recipient populations in adult heart transplant recipients, stratified based on concomitant azole antifungal use. Concomitant azole antifungal therapy alters tacrolimus pharmacokinetics substantially necessitating dose adjustments.

    METHODS: Population pharmacokinetic models of tacrolimus were selected (n=17) for evaluation from a recent systematic review. The models were transcribed and implemented in NONMEM version 7.4.3. Data from 85 heart transplant recipients (2387 tacrolimus concentrations) administered the oral immediate-release formulation of tacrolimus (Prograf®) were obtained up to 391 days post-transplant. The performance of each model was evaluated using (1) prediction-based assessment (bias and imprecision) of the individual predicted tacrolimus concentration of the fourth dosing occasion (MAXEVAL=0, FOCE-I) from 1-3 prior dosing occasions and (2) simulation-based assessment (prediction-corrected visual predictive check, pcVPC). Both assessments were stratified based on concomitant azole antifungal use.

    RESULTS: Regardless of the number of prior dosing occasions (1-3) and concomitant azole antifungal use, all models demonstrated unacceptable individual predicted tacrolimus concentration of the fourth dosing occasion (n=152). The pcVPC graphics indicated these models inadequately predicted observed tacrolimus concentrations.

    CONCLUSIONS: All models evaluated were unable to adequately describe tacrolimus pharmacokinetics in adult heart transplant recipients included in this study. Further work is required to describe tacrolimus pharmacokinetics for our heart transplant recipient cohort.

  6. Chow NK, Harun SN, Wong EJ, Low LL, Sheikh Ghadzi SM, Khan AH
    Br J Clin Pharmacol, 2021 10;87(10):3756-3765.
    PMID: 33608883 DOI: 10.1111/bcp.14783
    AIMS: Efavirenz is still widely used as the preferred first-line antiretroviral agent in middle- and low-income countries, including Malaysia. The efavirenz population pharmacokinetic profile among HIV-positive smokers is still unknown. We aimed to assess the association of smoking with efavirenz and the differences in HIV clinical outcomes.

    METHODS: A total of 154 stable HIV-positive patients on efavirenz in northern Malaysia were recruited with a sparse sampling for this multicentre prospective cohort study. The association between smoking and efavirenz pharmacokinetic parameters was determined using the nonlinear mixed-effect model. A mixture model of clearance was adopted to describe the metaboliser status because genetic data are unavailable. The effect of smoking on HIV clinical markers (CD4, CD4/CD8 ratio and viral blips) for at least 2 years after the antiretroviral initiation was also investigated.

    RESULTS: Our data were best fitted with a 1-compartment mixture model with first-order absorption without lag time. Smoking significantly associated with higher clearance (β = 1.39; 95% confidence interval: 1.07 to 1.91), while weight affected both clearance and volume. From the mixture model, 20% of patients were in the slow clearance group, which mimic the genotype distribution of slow metaboliser. An efavirenz dose reduction is not recommended for smokers ≥60 kg with normal metabolism rate. Smoking significantly associated with slower normalisation of CD4 and CD4/CD8 ratio.

    CONCLUSIONS: HIV-positive smokers presented with significantly higher efavirenz clearance and unfavourable clinical outcomes. Close monitoring of adherence and clinical response among smokers is warranted.

  7. Thapa P, Lee SWH, Kc B, Dujaili JA, Mohamed Ibrahim MI, Gyawali S
    Br J Clin Pharmacol, 2021 08;87(8):3028-3042.
    PMID: 33486825 DOI: 10.1111/bcp.14745
    AIMS: Pharmacists have been contributing to the management of chronic pain, ensuring the quality use of medicine. However, there is diversity in the interventions provided by pharmacists and their impact.

    METHODS: Six electronic databases were searched from inception until June 2020 for articles published in English examining the intervention provided by the pharmacist in chronic pain management. Studies investigating the impact of pharmacist intervention individually or multidisciplinary teams including pharmacists for chronic pain management were included.

    RESULTS: Fourteen studies (2365 participants) were included in the current review. Six studies were randomized controlled trials while the remainder were observational studies in which pharmacists provided intervention individually or in collaboration with other healthcare professionals. Medication review was the most common intervention provided by the pharmacist. The pooled analysis found that pharmacist-led interventions reduced the pain intensity (-0.22; 95% confidence interval [CI]: -0.35 to -0.09; moderate certainty) among participants with chronic pain. Opiate stewardship provided by pharmacists was effective; however, mixed results were noted on the impact of the intervention on physical functioning, anxiety, depression and quality of life. Pharmacist intervention was more expensive than treatment as usual.

    CONCLUSIONS: Pharmacists contribute substantially to chronic pain management, ensuring the quality use of medicine, resulting in reduced pain intensity. Further studies with rigorous design are needed to measure the impact of pharmacist-provided intervention individually or in a multidisciplinary team on the economic benefit and other health outcomes.

  8. Sugiarto SR, Singh B, Page-Sharp M, Davis WA, Salman S, Hii KC, et al.
    Br J Clin Pharmacol, 2022 Feb;88(2):691-701.
    PMID: 34296469 DOI: 10.1111/bcp.15001
    AIMS: The aim of this study was to assess the pharmacokinetic properties of artemether, lumefantrine and their active metabolites in Plasmodium knowlesi malaria.

    METHODS: Malaysian adults presenting with uncomplicated P. knowlesi infections received six doses of artemether (1.7 mg/kg) plus lumefantrine (10 mg/kg) over 3 days. Venous blood and dried blood spot (DBS) samples were taken at predetermined time-points over 28 days. Plasma and DBS artemether, dihydroartemisinin, lumefantrine and desbutyl-lumefantrine were measured using liquid chromatography-mass spectrometry. Multi-compartmental population pharmacokinetic models were developed using plasma with or without DBS drug concentrations.

    RESULTS: Forty-one participants (mean age 45 years, 66% males) were recruited. Artemether-lumefantrine treatment was well tolerated and parasite clearance was prompt. Plasma and DBS lumefantrine concentrations were in close agreement and were used together in pharmacokinetic modelling, but only plasma concentrations of the other analytes were used because of poor correlation with DBS levels. The areas under the concentration-time curve (AUC0-∞ ) for artemether, dihydroartemisinin and lumefantrine (medians 1626, 1881 and 625 098 μg.h/L, respectively) were similar to those reported in previous pharmacokinetic studies in adults and children. There was evidence of auto-induction of artemether metabolism (mean increase in clearance relative to bioavailability 25.2% for each subsequent dose). The lumefantrine terminal elimination half-life (median 9.5 days) was longer than reported in healthy volunteers and adults with falciparum malaria.

    CONCLUSION: The disposition of artemether, dihydroartemisinin and lumefantrine in knowlesi malaria largely parallels that in other human malarias. DBS lumefantrine concentrations can be used in pharmacokinetic studies but DBS technology is currently unreliable for the other analytes.

  9. Mak WY, Ooi QX, Cruz CV, Looi I, Yuen KH, Standing JF
    Br J Clin Pharmacol, 2023 Jan;89(1):330-339.
    PMID: 35976674 DOI: 10.1111/bcp.15496
    AIM: nlmixr offers first-order conditional estimation (FOCE), FOCE with interaction (FOCEi) and stochastic approximation estimation-maximisation (SAEM) to fit nonlinear mixed-effect models (NLMEM). We modelled metformin's pharmacokinetic data using nlmixr and investigated SAEM and FOCEi's performance with respect to bias and precision of parameter estimates, and robustness to initial estimates.

    METHOD: Compartmental models were fitted. The final model was determined based on the objective function value and inspection of goodness-of-fit plots. The bias and precision of parameter estimates were compared between SAEM and FOCEi using stochastic simulations and estimations. For robustness, parameters were re-estimated as the initial estimates were perturbed 100 times and resultant changes evaluated.

    RESULTS: The absorption kinetics of metformin depend significantly on food status. Under the fasted state, the first-order absorption into the central compartment was preceded by zero-order infusion into the depot compartment, whereas for the fed state, the absorption into the depot was instantaneous followed by first-order absorption from depot into the central compartment. The means of relative mean estimation error (rMEE) ( ME E SAEM ME E FOCEi ) and rRMSE ( RMS E SAEM RMS E FOCEi ) were 0.48 and 0.35, respectively. All parameter estimates given by SAEM appeared to be narrowly distributed and were close to the true value used for simulation. In contrast, the distribution of estimates from FOCEi were skewed and more biased. When initial estimates were perturbed, FOCEi estimates were more biased and imprecise.

    DISCUSSION: nlmixr is reliable for NLMEM. SAEM was superior to FOCEi in terms of bias and precision, and more robust against initial estimate perturbations.

  10. Chong HY, Lim KS, Fong SL, Shabaruddin FH, Dahlui M, Mei Lai PS, et al.
    Br J Clin Pharmacol, 2023 Nov;89(11):3340-3351.
    PMID: 37294011 DOI: 10.1111/bcp.15818
    AIMS: Despite the availability of newer antiseizure medications, carbamazepine (CBZ) remains the gold standard. However, patients of Asian ancestry are susceptible to CBZ-related severe cutaneous adverse reactions. Universal HLA-B*15:02 screening is a promising intervention to address this. With the increasing recognition of integrating real-world evidence in economic evaluations, the cost-effectiveness of universal HLA-B*15:02 screening was assessed using available real-world data in Malaysia.

    METHODS: A hybrid model of a decision tree and Markov model was developed to evaluate 3 strategies for treating newly diagnosed epilepsy among adults: (i) CBZ initiation without HLA-B*15:02 screening (current practice); (ii) universal HLA-B*15:02 screening prior to CBZ initiation; and (iii) alternative prescribing without HLA-B*15:02 screening. The model was populated with real-world inputs derived from the Malaysian population. From a societal perspective, base-case analysis and sensitivity analyses estimated the costs and outcomes over a lifetime. Incremental cost-effectiveness ratios were calculated.

    RESULTS: In the base-cases analysis, universal HLA-B*15:02 screening yielded the lowest total costs and the highest total quality-adjusted life years (QALYs) gained. Compared with current practice, universal screening was less costly by USD100 and more effective by QALYs increase of 0.1306, while alternative prescribing resulted in 0.1383 QALYs loss at additional costs of USD332. The highest seizure remission rate (56%) was estimated for universal HLA-B*15:02 screening vs. current practice (54%) and alternative prescribing (48%).

    CONCLUSION: Our study suggests that universal HLA-B*15:02 screening is a cost-effective intervention in Malaysia. With the demonstrated value of real-world evidence in economic evaluations, more relevant standardization efforts should be emphasized to better inform decision-making.

  11. Veettil SK, Sadoyu S, Bald EM, Chandran VP, Khuu SAT, Pitak P, et al.
    Br J Clin Pharmacol, 2022 Feb;88(4):1551-1566.
    PMID: 34622475 DOI: 10.1111/bcp.15103
    AIMS: The aim was to perform an umbrella review to summarise the existing evidence on proton-pump inhibitor (PPI) use and adverse outcomes and to grade the certainty of evidence.

    METHODS: Electronic databases were searched up to July 2021 for meta-analyses of cohort studies and/or randomised controlled trials (RCTs). Summary effect sizes from a random-effects model, between-study heterogeneity, 95% prediction interval, small-study effect, excess significance and credibility ceilings were devised to classify the credibility of evidence from meta-analyses of cohort studies, whereas the GRADE approach was used for meta-analyses of RCTs.

    RESULTS: In meta-analyses of cohort studies, 52 of the 91 examined associations were statistically significant (P ≤ .05). Convincing evidence emerged from main analysis for the association between PPI use and risk of all-site fracture and chronic kidney disease in the elderly population. However, none of these associations remained supported by convincing evidence after sensitivity analyses. The use of PPI is also associated with an increased risk of mortality due to COVID-19 infection and other related adverse outcomes, but the quality of evidence was weak. In meta-analyses of RCTs, 38 of the 63 examined associations were statistically significant. However, no associations were supported by high or moderate-quality evidence.

    CONCLUSION: This study's findings imply that most putative adverse outcomes associated with PPI use may not be supported by high-quality evidence and are likely to have been affected by underlying confounding factors. Future research is needed to confirm the causal association between PPI use and risk of fracture and chronic kidney disease.

  12. Kongpakwattana K, Sawangjit R, Tawankanjanachot I, Bell JS, Hilmer SN, Chaiyakunapruk N
    Br J Clin Pharmacol, 2018 Jul;84(7):1445-1456.
    PMID: 29637593 DOI: 10.1111/bcp.13604
    AIMS: To determine the most efficacious and acceptable treatments of agitation in dementia.

    METHODS: MEDLINE, EMBASE, PsycINFO, CENTRAL and clinicaltrials.gov were searched up to 7 February 2017. Two independent reviewers selected randomized controlled trials (RCTs) of treatments to alleviate agitation in people with all-types dementia. Data were extracted using standardized forms and study quality was assessed using the revised Cochrane Risk of Bias Tool for RCTs. Data were pooled using meta-analysis. The primary outcome, efficacy, was 8-week response rates defined as a 50% reduction in baseline agitation score. The secondary outcome was treatment acceptability defined as treatment continuation for 8 weeks.

    RESULTS: Thirty-six RCTs comprising 5585 participants (30.9% male; mean ± standard deviation age, 81.8 ± 4.9 years) were included. Dextromethorphan/quinidine [odds ratio (OR) 3.04; 95% confidence interval (CI), 1.63-5.66], risperidone (OR 1.96; 95% CI, 1.49-2.59) and selective serotonin reuptake inhibitors as a class (OR 1.61; 95% CI, 1.02-2.53) were found to be significantly more efficacious than placebo. Haloperidol appeared less efficacious than nearly all comparators. Most treatments had noninferior treatment continuation compared to placebo, except oxcarbazepine, which was inferior. Findings were supported by subgroup and sensitivity analyses.

    CONCLUSIONS: Risperidone, serotonin reuptake inhibitors as a class and dextromethorphan/quinidine demonstrated evidence of efficacy for agitation in dementia, although findings for dextromethorphan/quinidine were based on a single RCT. Our findings do not support prescribing haloperidol due to lack of efficacy, or oxcarbazepine due to lack of acceptability. The decision to prescribe should be based on comprehensive consideration of the benefits and risks, including those not evaluated in this meta-analysis.

  13. Holford N, O'Hanlon CJ, Allegaert K, Anderson B, Falcão A, Simon N, et al.
    Br J Clin Pharmacol, 2024 Apr;90(4):1066-1080.
    PMID: 38031322 DOI: 10.1111/bcp.15978
    AIMS: We propose using glomerular filtration rate (GFR) as the physiological basis for distinguishing components of renal clearance.

    METHODS: Gentamicin, amikacin and vancomycin are thought to be predominantly excreted by the kidneys. A mixed-effects joint model of the pharmacokinetics of these drugs was developed, with a wide dispersion of weight, age and serum creatinine. A dataset created from 18 sources resulted in 27,338 drug concentrations from 9,901 patients. Body size and composition, maturation and renal function were used to describe differences in drug clearance and volume of distribution.

    RESULTS: This study demonstrates that GFR is a predictor of two distinct components of renal elimination clearance: (1) GFR clearance associated with normal GFR and (2) non-GFR clearance not associated with normal GFR. All three drugs had GFR clearance estimated as a drug-specific percentage of normal GFR (gentamicin 39%, amikacin 90% and vancomycin 57%). The total clearance (sum of GFR and non-GFR clearance), standardized to 70 kg total body mass, 176 cm, male, renal function 1, was 5.58 L/h (95% confidence interval [CI] 5.50-5.69) (gentamicin), 7.77 L/h (95% CI 7.26-8.19) (amikacin) and 4.70 L/h (95% CI 4.61-4.80) (vancomycin).

    CONCLUSIONS: GFR provides a physiological basis for renal drug elimination. It has been used to distinguish two elimination components. This physiological approach has been applied to describe clearance and volume of distribution from premature neonates to elderly adults with a wide dispersion of size, body composition and renal function. Dose individualization has been implemented using target concentration intervention.

  14. Kirubakaran R, Uster DW, Hennig S, Carland JE, Day RO, Wicha SG, et al.
    Br J Clin Pharmacol, 2023 Mar;89(3):1162-1175.
    PMID: 36239542 DOI: 10.1111/bcp.15566
    AIM: Existing tacrolimus population pharmacokinetic models are unsuitable for guiding tacrolimus dosing in heart transplant recipients. This study aimed to develop and evaluate a population pharmacokinetic model for tacrolimus in heart transplant recipients that considers the tacrolimus-azole antifungal interaction.

    METHODS: Data from heart transplant recipients (n = 87) administered the oral immediate-release formulation of tacrolimus (Prograf®) were collected. Routine drug monitoring data, principally trough concentrations, were used for model building (n = 1099). A published tacrolimus model was used to inform the estimation of Ka , V2 /F, Q/F and V3 /F. The effect of concomitant azole antifungal use on tacrolimus CL/F was quantified. Fat-free mass was implemented as a covariate on CL/F, V2 /F, V3 /F and Q/F on an allometry scale. Subsequently, stepwise covariate modelling was performed. Significant covariates influencing tacrolimus CL/F were included in the final model. Robustness of the final model was confirmed using prediction-corrected visual predictive check (pcVPC). The final model was externally evaluated for prediction of tacrolimus concentrations of the fourth dosing occasion (n = 87) from one to three prior dosing occasions.

    RESULTS: Concomitant azole antifungal therapy reduced tacrolimus CL/F by 80%. Haematocrit (∆OFV = -44, P 

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