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Since 2012, the U.S. Food and Drug Administration (FDA) has developed classification criteria of narrow therapeutic index (NTI) drug products and tightened bioequivalence (BE) standards for these products by recommending a fully replicated, two-sequence, two-treatment, four-period crossover study design where BE is based on passing both scaled average BE criterion and within-subject variability comparison criterion, as well as the average BE criterion of 80.00%-125.00%. Currently, the BE study design and criteria for NTI drugs are somewhat different across regulatory agencies. The objective of this study is to survey pharmacokinetic BE data of abbreviated new drug applications (ANDAs) of NTI drugs submitted to the FDA with initial submission dates between January 1, 2013 and October 1, 2022 to identify the impact of FDA’s current BE approach on generic NTI approval. Thirty-three NTI drug products from 100 ANDAs were identified with 93 ANDAs included in analysis. Eighty-seven ANDAs had four-way crossover studies, with 69 and 106 fed and fasting BE studies, respectively. For all NTI drugs, the range of average SWR for Cmax, AUCt, and AUCinf was between 0.05 and 0.27. Of the 20 studies that failed BE, 90%, 5%, and 5% failed reference scaled criteria only, variability comparison criteria only, and both, respectively. Further communication of this work with global regulatory agencies and the scientific community will help better understand current FDA NTI BE criteria and review experiences. These efforts will support the development of harmonized BE criteria for NTI drugs, in turn improving patient access to generic NTI drugs. [ABSTRACT FROM AUTHOR]

This study focuses on the evaluation and the drug release characteristics of a new coated matrix membrane (CMM) system, particularly emphasizing drug delivery from porous systems that offer more precise release control, especially for drugs with narrow therapeutic indexes (NTIs), such as theophylline. The parameters affecting the delivery of theophylline from the CMM were systematically studied. In the study, ethyl cellulose (ETC) served as the coating polymer, while poly (ethylene glycol) (PEG) was selected as the pore-forming agent. Poly (vinyl alcohol) (PVA) was used as the base polymer in the preparation of matrix membranes, and poly (vinyl pyrrolidone) (PVP) was preferred as the hydrophilicity balancing guest polymer. The effects of matrix membrane (MM) thickness, heat treatment temperature (HTT), coating layer thickness, drug loading concentration and coating layer porosity on the release rate of theophylline from CMM systems were all investigated. Additionally, the impacts of pH and temperature on theophylline release from CMM systems were examined. All experiments were conducted in vitro. By the study, 150 °C was determined as optimal HTT temperature. At more acidic pH values greater release rates were obtained. The release mechanism consistent with the Case I (Fickian) diffusion model and the activation energy for the permeation of theophylline through CMM systems was found as 62.355 J mol−1. As a result of the study, it was determined that the optimized CMM system with improved release properties can control the released amount of theophylline and it was proposed as a promising material for the dermal delivery of theophylline in vivo. A new drug delivery coated matrix membrane system for theophylline delivery. [ABSTRACT FROM AUTHOR]

Background: The recent exponential increase in legalized medical and recreational cannabis, development of medical cannabis programs, and production of unregulated over-the-counter products (e.g., cannabidiol (CBD) oil, and delta-8-tetrahydrocannabinol (delta-8-THC)), has the potential to create unintended health consequences. The major cannabinoids (delta-9- tetrahydrocannabinol and cannabidiol) are metabolized by the same cytochrome P450 (CYP) enzymes that metabolize most prescription medications and xenobiotics (CYP3A4, CYP2C9, CYP2C19). As a result, we predict that there will be instances of drug-drug interactions and the potential for adverse outcomes, especially for prescription medications with a narrow therapeutic index. Methods: We conducted a systematic review of all years to 2023 to identify real world reports of documented cannabinoid interactions with prescription medications. We limited our search to a set list of medications with predicted narrow therapeutic indices that may produce unintended adverse drug reactions (ADRs). Our team screened 4,600 reports and selected 151 full-text articles to assess for inclusion and exclusion criteria. Results: Our investigation revealed 31 reports for which cannabinoids altered pharmacokinetics and/or produced adverse events. These reports involved 16 different Narrow Therapeutic Index (NTI) medications, under six drug classes, 889 individual subjects and 603 cannabis/cannabinoid users. Interactions between cannabis/cannabinoids and warfarin, valproate, tacrolimus, and sirolimus were the most widely reported and may pose the greatest risk to patients. Common ADRs included bleeding risk, altered mental status, difficulty inducing anesthesia, and gastrointestinal distress. Additionally, we identified 18 instances (58%) in which clinicians uncovered an unexpected serum level of the prescribed drug. The quality of pharmacokinetic evidence for each report was assessed using an internally developed ten-point scale. Conclusion: Drug-drug interactions with cannabinoids are likely amongst prescription medications that use common CYP450 systems. Our findings highlight the need for healthcare providers and patients/care-givers to openly communicate about cannabis/cannabinoid use to prevent unintended adverse events. To that end, we have developed a free online tool (www.CANN-DIR.psu. edu) to help identify potential cannabinoid drug-drug interactions with prescription medications. [ABSTRACT FROM AUTHOR]

BackgroundThe recent exponential increase in legalized medical and recreational cannabis, development of medical cannabis programs, and production of unregulated over-the-counter products (e.g., cannabidiol (CBD) oil, and delta-8-tetrahydrocannabinol (delta-8-THC)), has the potential to create unintended health consequences. The major cannabinoids (delta-9-tetrahydrocannabinol and cannabidiol) are metabolized by the same cytochrome P450 (CYP) enzymes that metabolize most prescription medications and xenobiotics (CYP3A4, CYP2C9, CYP2C19). As a result, we predict that there will be instances of drug-drug interactions and the potential for adverse outcomes, especially for prescription medications with a narrow therapeutic index.MethodsWe conducted a systematic review of all years to 2023 to identify real world reports of documented cannabinoid interactions with prescription medications. We limited our search to a set list of medications with predicted narrow therapeutic indices that may produce unintended adverse drug reactions (ADRs). Our team screened 4,600 reports and selected 151 full-text articles to assess for inclusion and exclusion criteria.ResultsOur investigation revealed 31 reports for which cannabinoids altered pharmacokinetics and/or produced adverse events. These reports involved 16 different Narrow Therapeutic Index (NTI) medications, under six drug classes, 889 individual subjects and 603 cannabis/cannabinoid users. Interactions between cannabis/cannabinoids and warfarin, valproate, tacrolimus, and sirolimus were the most widely reported and may pose the greatest risk to patients. Common ADRs included bleeding risk, altered mental status, difficulty inducing anesthesia, and gastrointestinal distress. Additionally, we identified 18 instances (58%) in which clinicians uncovered an unexpected serum level of the prescribed drug. The quality of pharmacokinetic evidence for each report was assessed using an internally developed ten-point scale.ConclusionDrug-drug interactions with cannabinoids are likely amongst prescription medications that use common CYP450 systems. Our findings highlight the need for healthcare providers and patients/care-givers to openly communicate about cannabis/cannabinoid use to prevent unintended adverse events. To that end, we have developed a free online tool (www.CANN-DIR.psu.edu) to help identify potential cannabinoid drug-drug interactions with prescription medications.

Abstract Background Following solid organ transplantation, tacrolimus (TAC) is an essential drug in the immunosuppressive strategy. Its use constitutes a challenge due to its narrow therapeutic index and its high inter- and intra-pharmacokinetic (PK) variability. As the contribution of the gut microbiota to drug metabolism is now emerging, it might be explored as one of the factors explaining TAC PK variability. Herein, we explored the consequences of TAC administration on the gut microbiota composition. Reciprocally, we studied the contribution of the gut microbiota to TAC PK, using a combination of in vivo and in vitro models. Results TAC oral administration in mice resulted in compositional alterations of the gut microbiota, namely lower evenness and disturbance in the relative abundance of specific bacterial taxa. Compared to controls, mice with a lower intestinal microbial load due to antibiotics administration exhibit a 33% reduction in TAC whole blood exposure and a lower inter-individual variability. This reduction in TAC levels was strongly correlated with higher expression of the efflux transporter ABCB1 (also known as the p-glycoprotein (P-gp) or the multidrug resistance protein 1 (MDR1)) in the small intestine. Conventionalization of germ-free mice confirmed the ability of the gut microbiota to downregulate ABCB1 expression in a site-specific fashion. The functional inhibition of ABCB1 in vivo by zosuquidar formally established the implication of this efflux transporter in the modulation of TAC PK by the gut microbiota. Furthermore, we showed that polar bacterial metabolites could recapitulate the transcriptional regulation of ABCB1 by the gut microbiota, without affecting its functionality. Finally, whole transcriptome analyses pinpointed, among others, the Constitutive Androstane Receptor (CAR) as a transcription factor likely to mediate the impact of the gut microbiota on ABCB1 transcriptional regulation. Conclusions We highlight for the first time how the modulation of ABCB1 expression by bacterial metabolites results in changes in TAC PK, affecting not only blood levels but also the inter-individual variability. More broadly, considering the high number of drugs with unexplained PK variability transported by ABCB1, our work is of clinical importance and paves the way for incorporating the gut microbiota in prediction algorithms for dosage of such drugs. Video Abstract

Physiologically based biopharmaceutics modelling (PBBM) was recognised as potential approach for biopharmaceutics applications. However, PBBM to justify safety is an unexplored area. In this manuscript, we elucidated PBBM application for safety justification. Product DRL is a generic extended release tablet containing an anti-epileptic narrow therapeutic index (NTI) drug. During dossier review, regulatory agency requested to evaluate the impact of faster dissolution profiles observed during stability on safety aspects. In order to justify, PBBMbased strategy was adapted. Model was validated and population simulations were performed for reference and test formulations and the predictions matched with clinical outcome. The model was found to be sensitive to dissolution changes and hence applied for the prediction of stability batches exhibiting faster dissolution profiles, virtually generated profiles at lower and upper specifications. The maximum predicted plasma levels were well below the reported safety levels, thereby demonstrating safety of the product. Overall, a novel application of PBBM to justify safety was demonstrated. Similar justifications using PBBM and linking with safety can be adopted where safety can be impacted due to aggravated dissolution profiles. Such justifications have potential to avoid clinical safety studies and helps in faster approval of drug product. [ABSTRACT FROM AUTHOR]

Background: Following solid organ transplantation, tacrolimus (TAC) is an essential drug in the immunosuppressive strategy. Its use constitutes a challenge due to its narrow therapeutic index and its high inter- and intra-pharmacokinetic (PK) variability. As the contribution of the gut microbiota to drug metabolism is now emerging, it might be explored as one of the factors explaining TAC PK variability. Herein, we explored the consequences of TAC administration on the gut microbiota composition. Reciprocally, we studied the contribution of the gut microbiota to TAC PK, using a combination of in vivo and in vitro models. Results: TAC oral administration in mice resulted in compositional alterations of the gut microbiota, namely lower evenness and disturbance in the relative abundance of specific bacterial taxa. Compared to controls, mice with a lower intestinal microbial load due to antibiotics administration exhibit a 33% reduction in TAC whole blood exposure and a lower inter-individual variability. This reduction in TAC levels was strongly correlated with higher expression of the efflux transporter ABCB1 (also known as the p-glycoprotein (P-gp) or the multidrug resistance protein 1 (MDR1)) in the small intestine. Conventionalization of germ-free mice confirmed the ability of the gut microbiota to downregulate ABCB1 expression in a site-specific fashion. The functional inhibition of ABCB1 in vivo by zosuquidar formally established the implication of this efflux transporter in the modulation of TAC PK by the gut microbiota. Furthermore, we showed that polar bacterial metabolites could recapitulate the transcriptional regulation of ABCB1 by the gut microbiota, without affecting its functionality. Finally, whole transcriptome analyses pinpointed, among others, the Constitutive Androstane Receptor (CAR) as a transcription factor likely to mediate the impact of the gut microbiota on ABCB1 transcriptional regulation. Conclusions: We highlight for the first time how the modulation of ABCB1 expression by bacterial metabolites results in changes in TAC PK, affecting not only blood levels but also the inter-individual variability. More broadly, considering the high number of drugs with unexplained PK variability transported by ABCB1, our work is of clinical importance and paves the way for incorporating the gut microbiota in prediction algorithms for dosage of such drugs. 5nEvj3aohpq9uU8QResbYs Video Abstract [ABSTRACT FROM AUTHOR]

Introduction: The history of levothyroxine has been linked to advances in the treatment of thyroid disease and to date it is the standard therapy for the treatment of hypothyroidism. Bioequivalence studies are the most widely used method to demonstrate interchangeability, although controversy persists regarding the best design for this molecule declared as a narrow therapeutic index product in many countries. This study aimed to evaluate the pharmacokinetic profile of two formulations of levothyroxine to determine bioequivalence between them. Methods: This two-period, randomized, crossover, blind study was conducted in 80 healthy volunteers, of both sexes, using a single levothyroxine dose of 600 μg with a washout period of 42 days. Blood sampling was performed at − 30 min, − 15 min, and 0 h pre-dose and 30 min, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 16, 24, and 48 h post-dose. Results: A total of 78 subjects successfully completed both periods. There were no serious adverse events during the study and both formulations were well tolerated. Baseline correction of serum levothyroxine concentrations was performed before statistical analysis. The mean maximum plasma concentration of the test product (Levotiroxina MK®) was 57.49 ng/mL while for the reference product it reached 59.32 ng/mL. Importantly, both test and reference formulations reached maximum concentrations in plasma at about the same time. The areas under the pharmacokinetic curves with the test product showed AUC0−t of 1407.1 ng h/mL and the reference product 1394.3 ng h/mL. The bioequivalence statistical analysis showed that the 90% confidence interval (CI90%) of the ratio of test over reference formulation was within the bioequivalence margins of 90–111%. For Cmax, the test/reference ratio was 96.2% with CI90% of 91.6–100.9%, and for AUC0−t the test/reference ratio was 99.9 with CI90% of 93.3–107.0%. Conclusions: Both formulations have the same pharmacokinetic profile and are bioequivalent in the narrow therapeutic index required by some health authorities. [ABSTRACT FROM AUTHOR]

Background: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are breakthrough medicines for obesity treatment and have rapidly gained widespread clinical application. Although GLP-1RAs are generally not associated with drug-drug interactions (DDIs) via drug metabolism or transporter pathways, their effects on reduced gastrointestinal (GI) motility could influence the pharmacokinetics of coadministered oral medications., Objectives: This study uses physiologically based pharmacokinetic (PBPK) modeling to evaluate the DDI potential of GLP-1RA-induced GI motility delays., Methods: Using Certara's Simcyp™ Simulator V23, we modeled the pharmacokinetics of atorvastatin, metformin, metoprolol, ethinyl estradiol, and digoxin in a virtual cohort of obese adults (n = 1000). GLP-1RA-related gastric emptying delays were simulated based on capsule endoscopy data from liraglutide-treated patients. Results were compared with clinical data from semaglutide and liraglutide users. Additionally, exploratory analyses were conducted on frequently coadministered drugs identified from the 2022 Medical Expenditure Panel Survey, including rosuvastatin and dabigatran., Results: GLP-1RA-induced gastric emptying delays led to increased area under the concentration-time curve (AUC) and prolonged time to maximum concentration (Tmax) for several medications. The model outputs for rosuvastatin, valsartan, and dabigatran indicate increases in AUC by 64%, 90%, and 205%, respectively. Dabigatran, a narrow therapeutic index anticoagulant, exhibited the most significant changes, raising potential concerns of higher drug exposure., Conclusions: PBPK modeling suggests that GLP-1RAs can influence the pharmacokinetics of oral medications by delaying gastric emptying, potentially leading to clinically relevant DDIs. While further clinical validation and pharmacovigilance is needed, these findings highlight the importance of PBPK tools in predicting and potentially mitigating risks associated with GLP-1RA use., (© 2025 The Author(s). Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy published by Wiley Periodicals LLC on behalf of Pharmacotherapy Publications, Inc.)

Bioequivalence (BE) of products containing narrow therapeutic index (NTI) drugs in the European Union is currently established by demonstrating that the 90% confidence interval for the ratio of the population geometric means of the test compared to the reference product's AUC, and in certain cases Cmax, is included within the tighter acceptance range of 90.00–111.11%. An alternative criterion, consisting of narrowed limits based on the within-subject variability of the reference product, was recently proposed. Its performance for a three-period partial replicate design was tested by simulation in terms of power to show BE, type I error (T1E) and sample size requirements. A new condition, a constraint on the test-to-reference geometric mean ratio (cGMR) to be contained within the range of 90.00–111.11%, was also tested. The probability of showing BE when the products differ more than 10% was increased, but only if the reference product's within-subject variability was moderate-to-high. The inclusion of the additional cGMR limited this. An increase in the T1E (<7%) was observed. The inclusion of the additional cGMR did not change the highest inflation of the T1E. Finally, a significant sample size reduction was observed and the inclusion of the cGMR usually did not increase the required sample size. [ABSTRACT FROM AUTHOR]

An appropriate therapeutic index is crucial for drug discovery and development since narrow therapeutic index (NTI) drugs with slight dosage variation may induce severe adverse drug reactions or potential treatment failure. To date, the shared characteristics underlying the targets of NTI drugs have been explored by several studies, which have been applied to identify potential drug targets. However, the association between the drug therapeutic index and the related disease has not been dissected, which is important for revealing the NTI drug mechanism and optimizing drug design. Therefore, in this study, two classes of disease (cancers and cardiovascular disorders) with the largest number of NTI drugs were selected, and the target property of the corresponding NTI drugs was analyzed. By calculating the biological system profiles and human protein–protein interaction (PPI) network properties of drug targets and adopting an AI-based algorithm, differentiated features between two diseases were discovered to reveal the distinct underlying mechanisms of NTI drugs in different diseases. Consequently, ten shared features and four unique features were identified for both diseases to distinguish NTI from NNTI drug targets. These computational discoveries, as well as the newly found features, suggest that in the clinical study of avoiding narrow therapeutic index in those diseases, the ability of target to be a hub and the efficiency of target signaling in the human PPI network should be considered, and it could thus provide novel guidance in the drug discovery and clinical research process and help to estimate the drug safety of cancer and cardiovascular disease.

Kaja Gantar,1 Katja Škerget,1 Ilya Mochkin,2 Aleksander Bajc1 1Sandoz Development Center Slovenia, Lek Pharmaceuticals d.d, Ljubljana 1526, Slovenia; 2Sandoz International GmbH, Holzkirchen 83607, GermanyCorrespondence: Ilya MochkinSandoz International GmbH, Industriestraße 18, Holzkirchen 83607, GermanyEmail ilya.mochkin@sandoz.comAbstract: Despite growing clinical confidence in generics and their potential to reduce long-term healthcare costs, the transplant community have had real concerns about the use of generic immunosuppressants. One such immunosuppressant is tacrolimus, a cornerstone of lifelong treatment for patients who have undergone a solid organ transplant. Tacrolimus has a narrow therapeutic index (NTI), giving rise to questions about the potential for clinically relevant altered drug exposure. Its use in transplant patients also gives rise to questions about the most discriminative subject population for bioequivalence studies. The recognised need for stringent criteria to support approval of generic drugs with an NTI led the European Medicines Association and Health Canada to provide detailed information on requirements for bioequivalence studies and introduce tighter bioequivalence limits for these drugs, including tacrolimus. The aim of this article is to illustrate how regulatory guidance is implemented during the clinical development of generic immunosuppressants, using a generic, once-daily prolonged-release formulation of tacrolimus as an example.Keywords: tacrolimus, bioequivalence, narrow therapeutic index, once-daily, generic

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Distributed and point-of-care (POC) manufacturing facilities enable an agile pharmaceutical production paradigm that can respond to localized needs, providing personalized and precision medicine. These capabilities are critical for narrow therapeutic index drugs and pediatric or geriatric dosing, among other specialized needs. Advanced additive manufacturing, three-dimensional (3D) printing, and drop-on-demand (DoD) dispensing technologies have begun to expand into pharmaceutical production. We employed a quality by design (QbD) approach to identify critical quality attributes (CQAs), critical material attributes (CMAs), and critical process parameters (CPPs) of a POC pharmaceutical manufacturing paradigm. This theoretical framework encompasses the production of active pharmaceutical ingredient (API) "inks" at a centralized facility, which are distributed to POC sites for DoD dispensing into/onto delivery vehicles ( e.g. , orodispersible films, capsules, single liquid dose vials). Focusing on the POC dispensing/dosing processes, QbD considerations and cause-and-effect analyses identified the dispensed API quantity and solid-state form (CQAs), as well as the nozzle diameter, system pressure channel, and number of drops dispensed (CPPs) for detailed investigation. Final assay quantification and content uniformity CQAs were measured from demonstrative levothyroxine sodium single-dose liquid vials of glycerin/water, meeting the standard acceptance values. Each POC facility is unlikely to maintain full quality control laboratory capabilities, requiring the development of appropriate atline or inline methods to ensure quality control. We developed control strategies, including atline ultraviolet-visible (UV-vis) verification of the API ink prior to dispensing, inline drop counting during dispensing, intermediate atline-dispensed volume checks, and offline batch confirmation by liquid chromatography-tandem mass spectrometry (LC-MS/MS) following production.

Warfarin is a narrow therapeutic index anticoagulant drug, and several generic formulations have been approved worldwide. However, there has been no report evaluating the bioequivalence of warfarin sodium according to US Food and Drug Administration draft guidance. We designed a 2‐sequence and 4‐period crossover study to compare the pharmacokinetic profile and assess bioequivalence between the test warfarin sodium tablet and reference product Coumadin (2.5 mg) in 56 healthy Chinese subjects under fasting and fed conditions. The plasma concentration of warfarin was analyzed by a validated liquid chromatography‐tandem mass spectrometry assay, and the reference‐scaled procedure was used to determine bioequivalence for the pharmacokinetics parameters. The results showed that the point estimate of geometric mean ratios of Cmax and AUC0‐t for warfarin were 103.21% and 99.31%, respectively, in the fasting condition and 100.62% and 98.98%, respectively, in the fed condition, and the 90% confidence intervals were all within the range of 90.00%‐111.11%. The upper limit of the 90% confidence interval of estimated within‐subject variation ratios of the test and reference products was 1.33 for Cmax and 2.22 for AUC0‐t under the fasting condition and 1.68 for Cmax and 2.15 for AUC0‐t under the fed condition. Overall, bioequivalence of the 2 warfarin sodium products was demonstrated. [ABSTRACT FROM AUTHOR]

The sole approved therapeutic drug for sickle cell disease management is provided by hydroxyurea, requiring its precise detection and monitoring in biological matrices such as human blood serum for personalized treatment. Herein, we introduce a direct colorimetric detection method for hydroxyurea in serum using a metallo-supramolecular assembly called Vesi-ImCu that mimics the peroxidase enzyme. The Vesi-ImCu enzyme mimetic comprises a catalytically active copper center coordinated to synthetic imidazole containing surfactant and iminodiacetic acid capping moieties. By leveraging the peroxidase-like activity of Vesi-ImCu, we have demonstrated that it catalyzes the efficient production of nitric oxide from hydroxyurea that reacts with the Griess reagent, producing an intense pink color. This approach enables the naked-eye detection of hydroxyurea, with notable efficacy even in complex biological matrices such as human blood serum. The Vesi-ImCu suprazyme-based approach offers several advantages, including high sensitivity (limit of detection of 75 µM), clinically relevant dynamic range of hydroxyurea detection, minimum batch-to-batch variation, and the ability to perform mobile phone-based quantification. To our knowledge, this is the first report on direct colorimetric quantification of HU in serum. With its visual detection ability, high-end equipment-free quantification, user-friendliness and portability, the present enzyme mimetic holds great promise for point-of-care detection applications. [Display omitted] • Hydroxyurea (HU) is the sole therapeutic drug for sickle cell disease. • A supramolecular peroxidase-mimetic vesicle allows efficient HU sensing. • Colorimetric response detects clinically relevant HU concentration in serum. • Rapid, robust, selective, low-cost and equipment-free point-of-care HU sensing. • Mobile phone-based detection satisfies REASSURED criteria of sensors. [ABSTRACT FROM AUTHOR]

The article describes the development and production of tablets using direct compression of powder mixtures. The aim was to describe the impact of filler particle size and the time of lubricant addition during mixing on content uniformity according to the Good Manufacturing Practice (GMP) process validation requirements. Processes are regulated by complex directives, forcing the producers to validate, using sophisticated methods, the content uniformity of intermediates as well as final products. Cutting down of production time and material, shortening of analyses, and fast and reliable statistic evaluation of results can reduce the final price without affecting product quality. The manufacturing process of directly compressed tablets containing the low dose active pharmaceutical ingredient (API) warfarin, with content uniformity passing validation criteria, is used as a model example. Statistic methods have proved that the manufacturing process is reproducible. Methods suitable for elucidation of various properties of the final blend, e.g., measurement of electrostatic charge by Faraday pail and evaluation of mutual influences of researched variables by partial least square (PLS) regression, were used. Using these methods, it was proved that the filler with higher particle size increased the content uniformity of both blends and the ensuing tablets. Addition of the lubricant, magnesium stearate, during the blending process improved the content uniformity of blends containing the filler with larger particles. This seems to be caused by reduced sampling error due to the suppression of electrostatic charge.

Problems pertaining to evaluation of the interchangeability of drugs with the same international nonproprietary name and a narrow therapeutic index (NTI) are discussed. An analysis of 2073 spontaneous reports in the Russian database for the period 2009 - 2015 revealed information about adverse reactions that occurred upon mutual substitution of NTI drugs. Most communications about adverse side reactions referred to the substitution of calcineurin inhibitors and synthetic hypoglycemic drugs, in particular, cyclosporine (20.4% of the total body of data), tacrolimus (11.3%), and glibenclamide (16.5%). Most disorders with substitution of calcineurin inhibitors were observed in kidneys and the urinary tract; of glibenclamide, in the gastrointestinal tract. Significant percentages of cases referred to ineffective replacement of levothyroxine and warfarin besides glibenclamide. In most cases, the reference drug was tolerated well whereas switching to a generic led to a lack of efficacy and/or the development of adverse reactions. An analysis of the database showed that spontaneous communications can and should be taken into account during post-registration control of drugs that were initially accepted as interchangeable. [ABSTRACT FROM AUTHOR]

Development of age-appropriate formulation suitable for pediatric and geriatric patients involves various challenges. The objective of this research was to develop extended-release oral flexible tablet (ER-OFT) formulation using carbamazepine (CBZ) as model drug for pediatric and geriatric compliance. ER-microparticles of carbamazepine, a BCS class 2, and narrow therapeutic index (NTI) drug, were prepared using ethyl cellulose as matrixing polymer and hypromellose as hydrophilic pore former. Microparticles were prepared using high-shear granulator fitted with an atomizing spray system. Granulation of carbamazepine and ethyl cellulose (EC-FP) with ethanolic binder solution resulted in ER-microparticles with extended-release >16 h. Release kinetics of ER microparticles showed Higuchi model by drug diffusion and erosion. Korsemeyer-peppas release exponent ' n' value 0.42 suggested Fickian diffusion. ER-OFT was prepared by blending of ER-microparticles with water-insoluble compressible aid and disintegrating agent. ER-OFT was characterized for performance characteristics and elemental impurities. As the polymer content in formulation was <10%, the size of ER-OFT was smaller compared to marketed ER-formulations. ER-OFT showed in vitro disintegration time of <30 s as per USP and dispersion time of ∼60 to 180 s in 5 to 10 mL of water. Drug release profiles of ER-microparticles and ER-OFT were comparable as f2 values were >50. In vitro dissolution of ER-OFT was comparable to the marketed ER formulation in the pH range of GIT. ER-OFT can be orally swallowed, orally disintegrating, and used as dispersible tablets. Compared to non-disintegrating type ER-formulations, ER-OFT would provide uniform drug release in GIT with low within-subject variability an essential criterion for NTI drug. [ABSTRACT FROM AUTHOR]

This review provides a comprehensive list of in vivo and in vitro studies that have investigated alcohol induced dose dumping (AIDD) in modified release dosage forms. Of the numerous classes of drugs commercially available as modified release products, opioids, centrally acting drugs, and drugs with a narrow therapeutic index present high risks from dose dumping, despite being formulated in a manner that releases drug in a tailored or delayed fashion. Awareness of AIDD has led to the withdrawal of a few marketed products by Regulatory Agencies, and black box warnings on others. Since then, significant effort has focused on proving the robustness of a formulation when co-ingested with alcohol. Patient risk is deemed to be low if the formulation and its performance is unimpaired by the presence of 0-40% alcohol under in vivo and in vitro conditions. [ABSTRACT FROM AUTHOR]

Theophylline is a medicine with narrow therapeutic index. This implies that a small change in dosage would cause side effects. Theophylline is metabolized by CYP1A2 and CYP2E1. The aim of this review is to know the impact of CYP1A2 and CYP2E1 genes polymorphism on theophylline response. The review was done by searching literature in Pubmed and Science Direct databases with keywords ‘polymorphism’, ‘pharmacogenetic’, ‘CYP1A2’, ‘CYP2E1’ and ‘theophylline’. There were 5 research articles from Pubmed and 65 articles (21 research articles, 23 review articles and 21 book chapters) from Science Direct. The exclusion criteria were - articles discussing about polymorphism but not CYP1A2 or CYP2E1, the ones with a mention of theophylline but not about its metabolism, articles on CYP1A2 and/or 2E1 polymorphism but not on the effect on theophylline. Thus, 33 articles were reviewed due to their suitability. The review discusses the influence of polymorphism of CYP1A2 and CYP2E1 genes on theophylline response.

Résumé L’officine est équipée de logiciels permettant de détecter les interactions médicamenteuses sur les ordonnances, ce qui facilite grandement la tâche. Toutefois, lors d’une première lecture, il est nécessaire de se renseigner sur le profil du patient et les risques encourus. Pour cela, il convient de suivre une démarche précise et standardisée. Summary The community pharmacist is equipped with software which can detect drug interactions on prescriptions, greatly facilitating the pharmacist's task. However, with a first prescription, it is necessary to gather information about the patient's profile and the potential risks following a specific, standardised process. [ABSTRACT FROM AUTHOR]

Reference-scaled average bioequivalence (RSABE) has been recommended by Food and Drug Administration (FDA), and in its closely related form by European Medicines Agency (EMA), for the determination of bioequivalence (BE) of highly variable (HV) and narrow therapeutic index (NTI) drug products. FDA suggested that RSABE be evaluated by an approximating procedure. Development of an alternative, numerically exact approach was sought. A new algorithm, called Exact, was derived for the assessment of RSABE. It is based upon the observation that the statistical model of RSABE follows a noncentral t distribution. The parameters of the distribution were derived for crossover and parallel-group study designs. Simulated BE studies of HV and NTI drugs compared the power and consumer risk of the proposed Exact method with those recommended by FDA and EMA. The Exact method had generally slightly higher power than the FDA approach. The consumer risks of the Exact and FDA procedures were generally below the nominal error risk with both methods except for the partial replicate design under certain heteroscedastic conditions. The estimator of RSABE was biased; simulations demonstrated the appropriateness of Hedges' correction. The FDA approach had another, small but meaningful bias. The confidence intervals of RSABE, based on the derived exact, analytical formulas, are uniformly most powerful. Their computation requires in standard cases only a single-line program script. The algorithm assumes that the estimates of the within-subject variances of both formulations are available. With each algorithm, the consumer risk is higher than 5% when the partial replicate design is applied. [ABSTRACT FROM AUTHOR]

Ink-jet printing is a versatile, precise and relatively inexpensive method of depositing small volumes of solutions with remarkable accuracy and repeatability. Although developed primarily as a technology for image reproduction, its areas of application have expanded significantly in recent years. It is particularly suited to the manufacture of low dose medicines or to short production runs and so offers a potential manufacturing solution for the paradigm of personalised medicines. This review discusses the technical and clinical aspects of ink-jet printing that must be considered in order for the technology to become widely adopted in the pharmaceutical arena and considers applications in the literature. [ABSTRACT FROM AUTHOR]

Background: Warfarin is widely used for the prevention and treatment of cardiac, thromboembolic and hypercoagulable diseases. Since warfarin is a narrow therapeutic index medicine, it requires close monitoring when used in the outpatient setting and on long term basis. Warfarin has been found to be associated with a number of complications especially bleeding. Patients' knowledge on warfarin can improve anticoagulation control with decrease in adverse drug reaction and other associated complications. The objective was to assess knowledge level of warfarin therapy among its users and to provide adequate education and counseling to the patients. Methods: In the present cross sectional study, 34 patients on warfarin were interviewed. Patients' knowledge on warfarin was assessed using a validated Anticoagulation Knowledge Assessment (AKA) questionnaire comprising 29 questions. Each correct answer scored 3.45 points whereas an incorrect answer scored zero point. Patient who answered at least 21 questions correctly or scored (21 × 3.45 = 72.4 %) was considered to have adequate level of knowledge or have obtained a passing score. Association between independent variables and AKA score was assessed using Pearson Chi square test or Fisher's exact test for categorical variables. Patients were counseled regarding proper warfarin use by the researcher pharmacists at the end of each data collection schedule. Results: Of the 34 patients, only 5.8 % (n = 2) achieved a passing score whereas 94.1 % (n = 32) failed to achieve the passing score. 67.6 % of the patients (n = 23) achieved a score below 50 %. More than 50 % of the patients incorrectly answered 15 questions in the questionnaire. None of the patients scored 100 %. No significant association was found between age, gender of patients and total warfarin score. A significant association (p < 0.05) was found between duration of warfarin therapy and total warfarin score. Conclusions: Warfarin knowledge was poor among the patients. Hence, regular counseling with timely assessment of their understanding was felt necessary. [ABSTRACT FROM AUTHOR]

Objective To test the current U.S. Food and Drug Administration ( FDA) bioequivalence standard in a comparison of generic and brand-name drug pharmacokinetic ( PK) performance in 'generic-brittle' patients with epilepsy under clinical use conditions. Methods This randomized, double-blind, multiple-dose, steady-state, fully replicated bioequivalence study compared generic lamotrigine to brand-name Lamictal in 'generic-brittle' patients with epilepsy (n = 34) who were already taking lamotrigine. Patients were repeatedly switched between masked Lamictal and generic lamotrigine. Intensive PK blood sampling at the end of each 2-week treatment period yielded two 12-h PK profiles for brand-name and generic forms for each patient. Steady-state area under the curve ( AUC), peak plasma concentration (Cmax), and minimum plasma concentration (Cmin) data were subjected to conventional average bioequivalence ( ABE) analysis, reference-scaled ABE analysis, and within-subject variability ( WSV) comparisons. In addition, generic-versus-brand comparisons in individual patients were performed. Secondary clinical outcomes included seizure frequency and adverse events. Results Generic demonstrated bioequivalence to brand. The 90% confidence intervals of the mean for steady-state AUC, Cmax, and Cmin for generic-versus-brand were 97.2-101.6%, 98.8-104.5%, and 93.4-101.0%, respectively. The WSV of generic and brand were also similar. Individual patient PK ratios for generic-versus-brand were similar but not identical, in part because brand-versus-brand profiles were not identical, even though subjects were rechallenged with the same product. Few subjects had seizure exacerbations or tolerability issues with product switching. One subject, however, reported 267 focal motor seizures, primarily on generic, although his brand and generic PK profiles were practically identical. Significance Some neurologists question whether bioequivalence in healthy volunteers ensures therapeutic equivalence of brand and generic antiepileptic drugs in patients with epilepsy, who may be at increased risk for problems with brand-to-generic switching. Bioequivalence results in 'generic-brittle' patients with epilepsy under clinical conditions support the soundness of the FDA bioequivalence standards. Adverse events on generic were not related to the small, allowable PK differences between generic and brand. [ABSTRACT FROM AUTHOR]

Purpose: The therapeutic index (TI) is the range of doses at which a medication is effective without unacceptable adverse events. Drugs with a narrow TI (NTIDs) have a narrow window between their effective doses and those at which they produce adverse toxic effects. Generic drugs may be substituted for brand-name drugs provided that they meet the recommended bioequivalence (BE) limits. However, an appropriate range of BE for NTIDs is essential to define due to the potential for ineffectiveness or adverse events. Flecainide is an antiarrhythmic agent that has the potential to be considered an NTID. This review aims to evaluate the literature surrounding guidelines on generic substitution for NTIDs and to evaluate the evidence for flecainide to be considered an NTID. Methods: A review of recommendations from various regulatory authorities regarding BE and NTIDs, and publications regarding the NTID characteristics of flecainide, was carried out. Results: Regulatory authorities generally recommend reduced BE limits for NTIDs. Some, but not all, regulatory authorities specify flecainide as an NTID. The literature review demonstrated that flecainide displays NTID characteristics including a steep drug dose-response relationship for safety and efficacy, a need for therapeutic drug monitoring of pharmacokinetic (PK) or pharmacodynamics measures and intra-subject variability in its PK properties. Conclusions: There is much evidence for flecainide to be considered an NTID based on both preclinical and clinical data. A clear understanding of the potential of proarrhythmic effects or lack of efficacy, careful patient selection and regular monitoring are essential for the safe and rational administration of flecainide. [ABSTRACT FROM AUTHOR]

The principles for assessing therapeutic equivalence based on bioequivalence studies as accepted in Russia are significantly different from those adopted abroad, in particular with respect to drugs with narrow therapeutic indices (NTI). Certification of these drugs based on bioequivalence studies with commonly recognized limits is unacceptable in practice because drugs in this concentration range can cause serious adverse side effects and be more dangerous than the reference drug. The situation becomes especially critical when the reference drug is replaced by a generic. This circumstance creates the need to develop stricter regulations for NTI drugs. This article analyzes possible approaches to planning bioequivalence investigations for NTI drugs as adopted by leading world regulatory institutions in order to harmonize them with bioequivalence studies of NTI drugs in the Russian Federation. General recommendations for planning bioequivalence studies of NTI drugs were formulated based on the analysis. [ABSTRACT FROM AUTHOR]

Levothyroxine is a narrow therapeutic index, and to avoid adverse effect associated with under or excessive dosage, the dose response is carefully titrated. The tablets are marketed with a score providing an option to split. However, there are no systematic studies evaluating the effect of splitting on dose accuracy, and current study was undertaken to evaluate effects of splitting and potential causes for uniformity failures by measuring assay and content uniformity in whole and split tablets. Stability was evaluated by assaying drug for a period of 8 weeks. Effect of formulation factors on splittability was evaluated by a systematic investigation of formulation factors by preparing levothyroxine tablets in house by varying the type of excipients (binder, diluent, disintegrant, glidant) or by varying the processing factors (granulating liquid, mixing type, compression pressure). The tablets were analyzed using novel analytical tool such as near infrared chemical imaging to visualize the distribution of levothyroxine. Assay was not significantly different for whole versus split tablets irrespective of method of splitting (hand or splitter), and splitting also had no measurable impact on the stability. Split tablets either by hand or splitter showed higher rate of content uniformity failures as compared to whole tablets. Tablet splitter produced more fragmentation and, hence, more content uniformity and friability failures. Chemical imaging data revealed that the distribution of levothyroxine was heterogeneous and was dependent on type of binder and the process used in the manufacture of tablets. Splitting such tablets could prove detrimental if sub- or super-potency becomes an issue. [ABSTRACT FROM AUTHOR]

Immunosuppressants are considered critical dose/narrow therapeutic index drugs and there is the lingering suspicion among physicians and patients that generic versions may differ in quality and therapeutic efficacy from the brand name drug. The innovator's and the generic active drug molecule are exactly the same and are produced following exactly the same tight rules of good manufacturing practice. Upon oral administration, the drug molecule separates from the formulation and passes the membranes of gut mucosa cells; from this point on, the formulation has no influence on the kinetics of a drug and its biological effects. As formulations may differ, bioequivalence testing in healthy volunteer studies establishes equal relative oral bioavailability. Due to the number of patients required to achieve sufficient statistical power, to test the therapeutic equivalence of two formulations of the same drug with the same bioavailability is an unrealistic goal. An often overlooked fact is that the approval by drug regulatory agencies of several post-approval versions of the innovators’ immunosuppressants is based on the identical guidelines used for approval of generics. The FDA has issued specific guidelines describing the requirements for approval of generic versions of tacrolimus, sirolimus, and mycophenolic acid. The standard average bioequivalence approach is recommended and in the cases of tacrolimus and sirolimus, the effect of food should also be tested. No studies in the patient population are requested. Immunosuppressants are not regarded as drugs that require a special status to establish bioequivalence between generic and the innovator's versions. [ABSTRACT FROM AUTHOR]

Theophylline is a medicine with narrow therapeutic index. This implies that a small change in dosage would cause side effects. Theophylline is metabolized by CYP1A2 and CYP2E1. The aim of this review is to know the impact of CYP1A2 and CYP2E1 genes polymorphism on theophylline response. The review was done by searching literature in Pubmed and Science Direct databases with keywords 'polymorphism', 'pharmacogenetic', 'CYP1A2', 'CYP2E1' and 'theophylline'. There were 5 research articles from Pubmed and 65 articles (21 research articles, 23 review articles and 21 book chapters) from Science Direct. The exclusion criteria were - articles discussing about polymorphism but not CYP1A2 or CYP2E1, the ones with a mention of theophylline but not about its metabolism, articles on CYP1A2 and/or 2E1 polymorphism but not on the effect on theophylline. Thus, 33 articles were reviewed due to their suitability. The review discusses the influence of polymorphism of CYP1A2 and CYP2E1 genes on theophylline response. [ABSTRACT FROM AUTHOR]

Abstract: Switching between bioequivalent antiepileptic drugs (AEDs) in patients with epilepsy remains a concern because of possible untoward effects owing to a narrow therapeutic range. We investigated the association between switching A-rated AEDs and epilepsy-related events. We conducted a case–control study using claims from the MarketScan database. Cases were defined by an emergently treated epilepsy-related event with the primary diagnosis of epilepsy. Controls had an epilepsy outpatient office visit. Eighty-four of 757 (11.1%) cases and 147 of 2271 (6.5%) controls experienced an A-rated switch. The odds of an epilepsy-related event were 1.78-fold higher for switchers (95% CI 1.35 to 2.36) and, when adjusted for gender and total number of AED prescriptions filled, 1.57-fold higher (95% CI=1.17–2.10). Switching between A-rated formulations of AEDs is associated with an increased risk of emergently treated epilepsy-related events. These findings suggest that care should be taken when considering a switch between A-rated AEDs in patients with epilepsy. [Copyright &y& Elsevier]

Study Objectives. To determine the odds of antiepileptic drug substitution among patients who had an epileptic event requiring acute care--ambulance service, emergency department visit, or hospitalization--relative to patients who did not have an event, and to compare these results with those from a recent study involving a similar method but different patients. Design. Case-control analysis. Data Source. United States health care claims from the PharMetrics database. Patients. A cohort of patients aged 12-64 years with a primary diagnosis of epilepsy between October 1, 2005, and December 31, 2006; 991 cases (patients who experienced an epileptic event requiring acute care) and 2973 controls (patients who did not have an event) were matched in a 1:3 ratio for sex, age, and type of epilepsy. Measurements and Main Results. Using discordant pairs analysis, we calculated the odds ratio of an epileptic event that required acute care occurring in patients whose antiepileptic drug underwent substitution to an A-rated (therapeutically equivalent) alternative (switch from branded product to generic, generic to branded, or generic to generic) versus those whose drugs were not substituted. For matched data, 109 (11.0%) of 991 cases had an A-rated antiepileptic drug substitution in the 6 months before the event, whereas only 186 (6.3%) of 2973 controls had a substitution (odds ratio 1.84, 95% confidence interval 1.44-2.36). Our results were similar to those of a previous study involving a different patient database, which showed substitution rates of 11.3% for cases versus 6.5% for controls (odds ratio 1.81, 95% confidence interval 1.25-2.63). Our sensitivity analyses were robust, and we found a temporal relationship in that numerous substitutions occurred in the month before the acute event. Conclusion. Patients who had an epileptic event requiring acute care were about 80% more likely than matched controls without an acute event to have recently had an antiepileptic drug substitution. Our replication of a previously published case-control analysis revealed a similar association between substitution involving A-rated antiepileptic drugs and subsequent epileptic events requiring acute care, thereby lending credibility to the findings. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the bioequivalence of three marketed formulations of sodium valproate 500mg enteric-coated tablets at steady-state in healthy, adult male human subjects in a multiple-dose cross-over study. Sodium valproate tablets were administered twice daily for four days and only the morning dose was administered on the fifth day during each period. Blood samples were collected pre-dose on days 1-5, and post-dose on day 5 over 12 hours in each period. Plasma concentrations were determined using a validated high performance liquid chromatography method. Both Encorate and Epilex (generic products) were bioequivalent to Vaparin (reference product) and all three products were well tolerated by all subjects. [ABSTRACT FROM AUTHOR]

For four decades, warfarin has been used extensively to treat thromboembolic disorders. Major advances in monitoring have been achieved through recognition of thromboplastin variability and implementation of the international normalized ratio (INR). Recommended INR ranges have shifted to lower intensity, and new clinical information has led to the potential for increased use of warfarin to prevent venous thromboembolism, to treat patients with prosthetic heart valves to prevent stroke in patients with atrial fibrillation, and to prevent death and recurrent events after myocardial infarction. Optimal management of the patient who requires a drug that has a narrow therapeutic index such as warfarin, remains challenging. Strategies to enhance patient outcomes with these drugs attempt to improve the risk-benefit ratio of such therapies, which requires optimizing the agent's effectiveness, improving its safety profile, or both. [ABSTRACT FROM AUTHOR]

Precise detection of important pharmaceuticals with narrow therapeutic index (NTI) is very critical as there is a small window between their effective dose and the doses at which the adverse reactions are very likely to appear. Regarding the fact that various pharmacokinetics will be plausible while considering pharmacogenetic factors and also differences between generic and brand name drugs, accurate detection of NTI will be more important. Current routine analytical techniques suffer from many drawbacks while using novel biosensors can bring up many advantages including fast detection, accuracy, low cost with simple and repeatable measurements. Recently the well-known carbon Nano-allotropes including carbon nanotubes and graphenes have been widely used for development of different Nano-biosensors for a diverse list of analytes because of their great physiochemical features such as high tensile strength, ultra-light weight, unique electronic construction, high thermo-chemical stability, and an appropriate capacity for electron transfer. Because of these exceptional properties, scientists have developed an immense interest in these nanomaterials. In this case, there are important reports to show the effective Nano-carbon based biosensors in the detection of NTI drugs and the present review will critically summarize the available data in this field. Therapeutic Index, Dose response curve for wide and narrow therapeutic index medications. Image 1 [ABSTRACT FROM AUTHOR]