Analyses of marketplace tacrolimus drug product quality: Bioactivity, NMR and LC–MS

Combating Alcohol Adduct Impurity in Immunosuppressant Drug Product Manufacturing: A Scientific Investigation for Enhanced Process Control

OBJECTIVE

This research aims to elucidate critical impurities in process validation batches of tacrolimus injection formulations, focusing on identification and characterization of previously unreported impurity at RRT 0.42, identified as the tacrolimus alcohol adduct. The potential root causes for the formation of new impurity was determined using structured risk assessment by cause and effect fishbone diagram. The primary objective was to propose mitigation plan and demonstrate the control of impurities with 6 month accelerated stability results in development batches.

METHODS

The investigation utilizes method validation and characterization studies to affirm the accuracy of quantifying the tacrolimus alcohol adduct. The research methodology employed different characterization techniques like rotational rheometer, ICP‒MS, MALDI-MS, 1H NMR, 13C NMR, and DEPT-135 NMR for structural elucidation. Additionally, the exact mass of the impurity is validated using electrospray ionization mass spectra.

RESULTS

Results indicate successful identification and characterization of the tacrolimus alcohol adduct. The study further explores the transformation of Tacrolimus monohydrate under various conditions, unveiling the formation of Tacrolimus hydroxy acid and proposing the existence of a novel degradation product, the Tacrolimus alcohol adduct. Six-month data from development lots utilizing Manufacturing Process II demonstrate significantly lower levels of alcohol adducts.

CONCLUSIONS

Manufacturing Process II, selectively locates Tacrolimus within the micellar core of HCO-60, this prevent direct contact of ethanol with Tacrolimus which minimizes impurity alcohol adduct formation. This research contributes to the understanding of tacrolimus formulations, offering ways to safeguard product integrity and stability during manufacturing and storage.

The Impact of Human Microbiotas in Hematopoietic Stem Cell and Organ Transplantation

The human microbiota heavily influences most vital aspects of human physiology including organ transplantation outcomes and transplant rejection risk. A variety of organ transplantation scenarios such as lung and heart transplantation as well as hematopoietic stem cell transplantation is heavily influenced by the human microbiotas. The human microbiota refers to a rich, diverse, and complex ecosystem of bacteria, fungi, archaea, helminths, protozoans, parasites, and viruses. Research accumulating over the past decade has established the existence of complex cross-species, cross-kingdom interactions between the residents of the various human microbiotas and the human body. Since the gut microbiota is the densest, most popular, and most studied human microbiota, the impact of other human microbiotas such as the oral, lung, urinary, and genital microbiotas is often overshadowed. However, these microbiotas also provide critical and unique insights pertaining to transplantation success, rejection risk, and overall host health, across multiple different transplantation scenarios. Organ transplantation as well as the pre-, peri-, and post-transplant pharmacological regimens patients undergo is known to adversely impact the microbiotas, thereby increasing the risk of adverse patient outcomes. Over the past decade, holistic approaches to post-transplant patient care such as the administration of clinical and dietary interventions aiming at restoring deranged microbiota community structures have been gaining momentum. Examples of these include prebiotic and probiotic administration, fecal microbial transplantation, and bacteriophage-mediated multidrug-resistant bacterial decolonization. This review will discuss these perspectives and explore the role of different human microbiotas in the context of various transplantation scenarios.

Precision Dosing Priority Criteria: Drug, Disease, and Patient Population Variables

The administered dose of a drug modulates whether patients will experience optimal effectiveness, toxicity including death, or no effect at all. Dosing is particularly important for diseases and/or drugs where the drug can decrease severe morbidity or prolong life. Likewise, dosing is important where the drug can cause death or severe morbidity. Since we believe there are many examples where more precise dosing could benefit patients, it is worthwhile to consider how to prioritize drug–disease targets. One key consideration is the quality of information available from which more precise dosing recommendations can be constructed. When a new more precise dosing scheme is created and differs significantly from the approved label, it is important to consider the level of proof necessary to either change the label and/or change clinical practice. The cost and effort needed to provide this proof should also be considered in prioritizing drug–disease precision dosing targets. Although precision dosing is being promoted and has great promise, it is underutilized in many drugs and disease states. Therefore, we believe it is important to consider how more precise dosing is going to be delivered to high priority patients in a timely manner. If better dosing schemes do not change clinical practice resulting in better patient outcomes, then what is the use? This review paper discusses variables to consider when prioritizing precision dosing candidates while highlighting key examples of precision dosing that have been successfully used to improve patient care.

Forced degradation of tacrolimus and the development of a UHPLC method for impurities determination

An ultra-high performance liquid chromatography method for simultaneous determination of tacrolimus impurities in pharmaceutical dosage forms has been developed. Appropriate chromatographic separation was achieved on a BEH C18 column using gradient elution with a total run time of 14 min. The method was applied to analyses of commercial samples and was validated in terms of linearity, precision, accuracy, sensitivity and specificity. It was found to be linear, precise and accurate in the range of 0.05 to 0.6 % of the impurities level in pharmaceutical dosage forms. Stability indicating power of the method was demonstrated by the results of forced degradation studies. The forced degradation study in solution revealed tacrolimus instability under stress alkaline, thermal, light and photolytic conditions and in the presence of a radical initiator or metal ions. The drug was stable at pH 3-5. Solid-state degradation studies conducted on amorphous tacrolimus demonstrated its sensitivity to light, elevated temperature, humidity and oxidation.

The Association of Tacrolimus Formulation Switching with Trough Concentration Variability: A Retrospective Cohort Study of Tacrolimus Use Post-Kidney Transplantation Based on National Drug Code (NDC) Numbers

INTRODUCTION

It was hypothesized that patients experiencing at least one tacrolimus formulation switch may require more frequent therapeutic drug monitoring, subsequent dose adjustments, and a potential for untoward clinical outcomes than patients who remain on a single formulation.

METHODS

Eligible patients were adult kidney transplant recipients with stable renal function at month 3 post-transplant and no evidence of acute rejection, receiving an oral, tacrolimus-based regimen. Patients were categorized into two groups (fixed or variable formulation) using the US National Drug Code (NDC) on the basis of tacrolimus formulation usage over the 12-month period.

RESULTS

A total of 305 patients were enrolled from four US transplant centers; 44 (14.4%) received multiple formulations and 261 (85.6%) received a single formulation. Mean number of tacrolimus dose adjustments and mean cumulative milligram dose change were not statistically different between the two groups. Mean trough-to-dose ratio, frequency of trough level measurements, and mean number of excursions above 120% or below 80% of the patient's mean trough concentration were significantly higher in the variable compared to the fixed formulation group.

CONCLUSION

A variable tacrolimus formulation regimen was associated with a higher frequency of trough level measurements and a greater number of excursions in trough levels compared with continuing on a fixed formulation regimen of tacrolimus in this retrospective chart review study.

FUNDING

Astellas Pharma Global Development, Inc. Plain language summary available for this article.

Dissolution Test of Tacrolimus Capsule: Effects of Filtration and Glass Adsorption

Tacrolimus is a potent, narrow therapeutic index, immunosuppressive drug used to avoid organ rejection in patients that have undergone organ transplantation. Dissolution tests are widely used to evaluate drug product quality and performance. Analysis of tacrolimus during dissolution testing is sensitive to several factors, such as sample solution storage time and container material. The filtration process, tacrolimus glass adsorption, and sample solution storage time are found to impact the tacrolimus dissolution results. Based on observations in this work, the use of G4 or equivalent filter flush before collection and polypropylene test tubes or vials instead of glass test tubes or vials are recommended for tacrolimus drug product dissolution test.

Limustin®, a non-innovator tacrolimus formulation, yields reduced drug exposure in pediatric renal transplant recipients

The aim of this study was to evaluate the bioavailability of two oral tacrolimus formulations, the innovator Prograf(®) and a formulation commercialized in Mexico with the brand name Limustin(®), in children. Stable Mexican pediatric renal transplant recipients received the product authorized by their social security provider, being either Prograf(®) or Limustin(®). At steady state, blood samples were drawn and tacrolimus blood concentration against time curves was constructed. CYP3A5 genotype was also determined. There was no significant difference in dose or in trough concentrations between formulations. However, AUC and Cmax were significantly higher with Prograf(®). The lower tacrolimus bioavailability with Limustin(®) was observed in both expressers and non-expressers of the functional CYP3A5 protein. Dose-normalized AUC values in expressers were 12.7 ± 11.9 and 48.7 ± 20.4 ng·h/mL/mg for Limustin(®) and Prograf(®), whereas in non-expressers, dose-normalized AUC was 54.4 ± 49.1 and 110.4 ± 42.9 ng·h/mL/mg for Limustin(®) and Prograf(®), respectively (p < 0.05). Pharmaceutical quality analysis showed that Limustin(®) dissolution at 120 min was 31.1 ± 6.2% while Prograf(®) dissolution was 100 ± 4.8%. Furthermore, the mean percentage of labeled amount of Limustin(®) and Prograf(®) was 91.0 ± 3.1% and 100.0 ± 0.7%, respectively. Hence, Limustin(®) exhibits pharmaceutical characteristics dissimilar to the innovator that likely explain the reduced tacrolimus exposure in children. We consider Limustin(®) is not adequate for pediatric use.

Pharmaceutical impurities and degradation products: uses and applications of NMR techniques

Current standards and regulations demand the pharmaceutical industry not only to produce highly pure drug substances, but to achieve a thorough understanding of the impurities accompanying their manufactured drug substances and products. These challenges have become important goals of process chemistry and have steadily stimulated the search of impurities after accelerated or forced degradation procedures. As a result, impurity profiling is one of the most attractive, active and relevant fields of modern pharmaceutical analysis. This activity includes the identification, structural elucidation and quantitative determination of impurities and degradation products in bulk drugs and their pharmaceutical formulations. Nuclear magnetic resonance (NMR) spectroscopy has evolved into an irreplaceable approach for pharmaceutical quality assessment, currently playing a critical role in unequivocal structure identification as well as structural confirmation (qualitative detection), enabling the understanding of the underlying mechanisms of the formation of process and/or degradation impurities. NMR is able to provide qualitative information without the need of standards of the unknown compounds and multiple components can be quantified in a complex sample without previous separation. When coupled to separative techniques, the resulting hyphenated methodologies enhance the analytical power of this spectroscopy to previously unknown levels. As a result, and by enabling the implementation of rational decisions regarding the identity and level of impurities, NMR contributes to the goal of making better and safer medicines. Herein are discussed the applications of NMR spectroscopy and its hyphenated derivate techniques to the study of a wide range pharmaceutical impurities. Details on the advantages and disadvantages of the methodology and well as specific challenges with regards to the different analytical problems are also presented.