Ultra-High-Precision, in-vivo Pharmacokinetic Measurements Highlight the Need for and a Route Toward More Highly Personalized Medicine

Clinical drug dosing would, ideally, be informed by high-precision, patient-specific data on drug metabolism. The direct determination of patient-specific drug pharmacokinetics ("peaks and troughs"), however, currently relies on cumbersome, laboratory-based approaches that require hours to days to return pharmacokinetic estimates based on only one or two plasma drug measurements. In response clinicians often base dosing on age, body mass, pharmacogenetic markers, or other indirect estimators of pharmacokinetics despite the relatively low accuracy of these approaches. Here, in contrast, we explore the use of indwelling electrochemical aptamer-based (E-AB) sensors as a means of measuring pharmacokinetics rapidly and with high precision using a rat animal model. Specifically, measuring the disposition kinetics of the drug tobramycin in Sprague-Dawley rats we demonstrate the seconds resolved, real-time measurement of plasma drug levels accompanied by measurement validation via HPLC-MS on ex vivo samples. The resultant data illustrate the significant pharmacokinetic variability of this drug even when dosing is adjusted using body weight or body surface area, two widely used pharmacokinetic predictors for this important class of antibiotics, highlighting the need for improved methods of determining its pharmacokinetics.

Montelukast, current indications and prospective future applications

INTRODUCTION

Montelukast is recommended for the treatment of asthma, exercise -induced bronchospasm and allergic rhinitis. Several trials demonstrated potential therapeutic effects in other respiratory conditions, and different animal-model-based studies explored potential pharmacological actions in non-respiratory conditions.

AREAS COVERED

Clinical investigations on the pharmacotherapeutic effects of montelukast, in addition to in-vivo studies on animal models of non-respiratory diseases. The data discussed in this review were mainly obtained from clinical randomized trials, real-life studies, and studies based on animal models as approve of concept. As a condition, all of the discussed articles were published in journals cited by Pubmed. Expert commentary: The current clinical data are in favor of montelukast use in the management of chronic asthma as an add-on or alternative therapy to the inhaled corticosteroids. Further clinical trials are required to confirm the effectiveness and feasibility of montelukast for the treatment of conditions other than the current clinical indications.

The association between reduced folate carrier-1 gene 80G/A polymorphism and methotrexate efficacy or methotrexate related-toxicity in rheumatoid arthritis: A meta-analysis

Methotrexate (MTX), the most commonly used anti-rheumatic drug against RA, enters the cell via the action of the reduced folate carrier 1(RFC1). A major polymorphism of the RFC1 gene, 80G/A, has been reported to influence the activity of RFC1, resulting in variable intracellular MTX-polyglutamate (MTX-PG) levels. However, the association studies addressing the RFC1 80G/A polymorphism and MTX efficacy or toxicity in Rheumatoid arthritis (RA) has yielded conflicting results. In the present meta-analysis, we aimed to evaluate the association between the RFC1 80G/A polymorphism and MTX efficacy or toxicity in RA patients. A total 17 studies met our inclusion criteria. Among them, 12 studies with 2049 subjects reported the association between the RFC1 80G/A and MTX response, and 12 studies involving 2627 subjects were on MTX-related toxicity. Meta-analysis revealed significant association between RFC1 80G/A polymorphism and MTX efficacy (odds ratio (OR) for the A allele=1.29, 95% confidence interval (CI) 1.05-1.67, P=0.02; for AA genotype: OR=1.49, 95%CI 1.17-1.907, P=0.001). However, no association could be detected in the analysis of MTX-related toxicity. Stratification by ethnic population also indicated an association between this polymorphism and MTX efficacy in Asian group (P=0.002 for A allele; P=0.003 for AA genotype), but not in the Caucasian group (P=0.15 for A allele; P=0.05 for AA genotype). In both Asian and Caucasian sub-groups, no influence of the RFC1 80G/A polymorphism on MTX toxicity can be detected. In conclusion, the RFC1 G80A polymorphism is associated with responsiveness to MTX therapy, but may not be associated with MTX toxicity in RA patients.

[Implementation and Evaluation of Genetic Testing Seminars on Lifestyle-related Disease Prevention for Pharmacy Students]

The field of pharmacotherapy has advanced to use molecular targeted agents, and pharmacists are now encouraged to focus on pharmacogenomics. A seminar titled "Implementation and evaluation of genetic testing of lifestyle-related disease genes" was presented to students at the Faculty of Pharmaceutical Sciences, Hiroshima University, describing the pharmacogenomic role of single nucleotide polymorphisms in obesity-related genes and alcohol metabolism-related genes. The seminar topic was selected first because pharmaceutical students were already familiar with some of the content, and secondly because we believe that pharmacists should be informed about the prevention of lifestyle-related diseases using genetic testing. We evaluated the usefulness of this seminar by administering a questionnaire before and after the seminar to participating students. Several points requiring improvement were identified, although 82% of students stated that the seminar was "very useful" or "useful". We conclude that this educational seminar was useful to students of pharmaceutical sciences.

Interchangeability and comparative effectiveness between generic and brand montelukast immediate release tablets after a single oral administration in healthy volunteers

BACKGROUND

Montelukast is a leukotriene receptor antagonist. The release of leukotrienes causes narrowing and constricting in the respiratory airways. Blocking the action of these leukotrienes, montelukast can be used for the prophylaxis and treatment of chronic asthma.

OBJECTIVE

The aim of this study was to evaluate the interchangeability and comparative effectiveness between a generic and a brand montelukast 10 mg immediate release tablets (Broncast(®) and Singulair(®), respectively) after a single oral dose among Arab Mediterranean volunteers.

METHODS

An open-label, randomized two-period crossover bioequivalence design was conducted in 31 healthy male volunteers with a 1 week washout between each study period and under fasting conditions. The plasma drug concentration was assessed by using a previously validated LC MS/MS method. The ratio between the generic and brand of geometric least squares means was reported for both generic and brand products. Moreover, an in vitro dissolution study was conducted on generic and brand tablets using three different pH media, and similarity and non-similarity factors (f2 and f1) were calculated.

RESULTS

The used bioanalytical method was found to be linear within the range 6.098-365.855 ng/mL. The correlation coefficient was close to 0.999 during the course of the study validation. Statistical comparison of the main pharmacokinetic parameters showed the inexistence of any significant difference between generic and the brand. The point estimates (ratios of geometric means) were 111.939, 111.711, and 112.169 % for AUC0-24, AUC0-∞, and Cmax, respectively. The 90 % confidence intervals (CIs) were within the pre-defined limits of 80.00-125.00 % as specified by the FDA and EMA for bioequivalence studies. F2 and f1 were higher than 50 and lower than 15, respectively in all selected pH media.

CONCLUSION

Broncast(®) immediate release film coated tablets (10 mg/tablet) are bioequivalent to Singulair(®) immediate release film coated tablets (10 mg/tablet), with a comparable safety and efficacy profile. This suggests that these two formulations can be clinically considered interchangeable. The dissolution study suggests that it could be used as premarketing quality control parameter in order to maintain the high quality of the produced product.