Applying ASTM Standards to Tensile Tests of Musculoskeletal Soft Tissue: Methods to Reduce Grip Failures and Promote Reproducibility.

Tensile testing is an essential experiment to assess the mechanical integrity of musculoskeletal soft tissues, yet standard test methods have not been developed to ensure the quality and reproducibility of these experiments. The ASTM International standards organization has created tensile test standards for common industry materials that specify geometric dimensions of test specimens (coupons) that promote valid failures within the gage section (midsubstance), away from the grips. This study examined whether ASTM test standards for plastics, elastomers, and fiber-reinforced composites are suitable for tensile testing of bovine meniscus along the circumferential fiber direction. We found that dumbbell (DB) shaped coupons based on ASTM standards for elastomers and plastics had an 80% and 60% rate of midsubstance failures, respectively. The rate of midsubstance failures dropped to 20% when using straight (ST) coupons based on ASTM standards for fiber-reinforced composites. The mechanical properties of dumbbell shaped coupons were also significantly greater than straight coupons. Finite element models of the test coupons revealed stress distributions that supported our experimental findings. In addition, we found that a commercial deli-slicer was able to slice meniscus to uniform layer thicknesses that were within ASTM dimensional tolerances. This study provides methods, recommendations, and insights that can advance the standardization of tensile testing in meniscus and other soft fibrous tissues.

Screening for quality with process analytical technology in a health-system pharmacy: A primer.

PURPOSE: The University of Kentucky Drug Quality Study team briefly reviews the growing concerns over pharmaceutical manufacturing quality in the globalized environment, reviews the historical approach by the US Food and Drug Administration (FDA) that prioritizes process over product in enforcing quality with manufacturers, reviews the science of process analytical technology (PAT) such as near-infrared (NIR) spectroscopy, illustrates the use of PAT methods for assessing uniformity and quality in injectable pharmaceuticals, and demonstrates the application of NIR spectroscopy in a health-system pharmacy setting while maintaining current good practice quality guidelines and regulations (cGxP). SUMMARY: Given that the current approach to monitoring quality in pharmaceutical manufacturing was developed in the late 1960s at a time when manufacturing was mostly domestic, the current approach prioritizes process over product, and the global footprint of manufacturing is straining federal resources to fulfill their task of monitoring quality, an approach to augment the quality monitoring process has been developed. PAT methodologies are supported by FDA for monitoring quality and offer a fast, low-cost, nondestructive solution. Given that the Accreditation Council for Pharmacy Education has not required qualitative/quantitative analysis and drug assaying in the pharmacy curriculum for several decades, the authors spend time explaining the science behind one of these PAT methodologies, NIR spectroscopy. This primer reviews the application of this technology in the health-system pharmacy setting and the relevant clinical applications. CONCLUSION: Utilizing PAT methodologies such as NIR spectroscopy, health-system pharmacies can gain insights about whether process controls are in place or lacking in FDA-approved formulations.

Application of Near-Infrared Spectroscopy for Screening of Chlorothiazide Sodium Vials.

Chlorothiazide sodium for injection, USP, is a diuretic and antihypertensive medication in the form of a white or practically white, sterile, lyophilized powder. Each vial contains 500 mg of chlorothiazide sodium, equivalent to 500 mg of chlorothiazide, and 250 mg of mannitol as an inactive ingredient. The pH is adjusted with sodium hydroxide. Chlorothiazide sodium has a molecular weight of 317.71 amu. Since 2020 there have been multiple national shortages of chlorothiazide. Recent studies target chlorothiazide's low bioavailability, aiming to enhance it through nanoparticle production via a supercritical method. The drug's solubility in supercritical carbon dioxide (scCO2) is vital, with measurements ranging from 0.417×10-5 to 1.012×10-5 mole fraction under specific conditions. Adding co-solvents, like ethanol, DMSO, and acetone, to scCO2 boosts solubility, with ethanol proving most effective, enhancing solubility by 2.02-11.75 times. Intra-lot variability was discovered in a sample of a lot of chlorothiazide sodium by the University of Kentucky Drug Quality Task Force. Two vials of six screened in one lot were displaced from the center of the lot by 4.0 and 4.2 SDs, respectively. Inter-lot variability was confirmed in the near-IR spectra of 204 vials obtained from 28 different lots of chlorothiazide sodium. Using full spectrum BEST analysis 13 vials (6.4%) were outliers.

Modeling fatigue failure in soft tissue using a visco-hyperelastic model with discontinuous damage.

Soft tissue is susceptible to injury from single high-magnitude static loads and from repetitive low-magnitude fatigue loads. While many constitutive formulations have been developed and validated to model static failure in soft tissue, a modeling framework is not well-established for fatigue failure. Here we determined the feasibility of using a visco-hyperelastic damage model with discontinuous damage (strain energy-based damage criterion) to simulate low- and high-cycle fatigue failure in soft fibrous tissue. Cyclic creep data from six uniaxial tensile fatigue experiments of human medial meniscus were used to calibrate the specimen-specific material parameters. The model was able to successfully simulate all three characteristic stages of cyclic creep, and predict the number of cycles until tissue rupture. Mathematically, damage propagated under constant cyclic stress due to time-dependent viscoelastic increases in tensile stretch that in turn increased strain energy. Our results implicate solid viscoelasticity as a fundamental regulator of fatigue failure in soft tissue, where tissue with slow stress relaxation times will be more resistant to fatigue injury. In a validation study, the visco-hyperelastic damage model was able to simulate characteristic stress-strain curves of pull to failure experiments (static failure) when using material parameters curve fit to the fatigue experiments. For the first time, we've shown that a visco-hyperelastic discontinuous damage framework can model cyclic creep and predict material rupture in soft tissue, and may enable the reliable simulation of both fatigue and static failure behavior from a single constitutive formulation.

Finite element modeling of meniscal tears using continuum damage mechanics and digital image correlation.

Meniscal tears are a common, painful, and debilitating knee injury with limited treatment options. Computational models that predict meniscal tears may help advance injury prevention and repair, but first these models must be validated using experimental data. Here we simulated meniscal tears with finite element analysis using continuum damage mechanics (CDM) in a transversely isotropic hyperelastic material. Finite element models were built to recreate the coupon geometry and loading conditions of forty uniaxial tensile experiments of human meniscus that were pulled to failure either parallel or perpendicular to the preferred fiber orientation. Two damage criteria were evaluated for all experiments: von Mises stress and maximum normal Lagrange strain. After we successfully fit all models to experimental force-displacement curves (grip-to-grip), we compared model predicted strains in the tear region at ultimate tensile strength to the strains measured experimentally with digital image correlation (DIC). In general, the damage models underpredicted the strains measured in the tear region, but models using von Mises stress damage criterion had better overall predictions and more accurately simulated experimental tear patterns. For the first time, this study has used DIC to expose strengths and weaknesses of using CDM to model failure behavior in soft fibrous tissue.

Spectrometric Analysis of Dantrolene Sodium.

Dantrolene sodium is a direct-acting skeletal muscle relaxant. Dantrolene sodium for injection is indicated, along with suitable supportive measures, for the management of sudden, severe hypermetabolism of skeletal muscle typical of malignant hyperthermia crises in patients of any age. The formulation scanned in this work was designed to be injected intravenously. Intra-lot and inter-lot variability in the spectra of REVONTO™ (dantrolene sodium) was measured in the Drug Quality Study (DQS) using Fourier transform near-infrared spectrometry (FTNIR). Spectra of 69 vials from lot 20REV01A contained two groups (n1=56 vials, n2=13 vials) when scanned with an FTNIR. The two groups of spectra in lot 20REV01A were found to be 66.7 SDs apart using a subcluster detection test, suggesting that the two groups were manufactured differently. As a result, all available samples of dantrolene were examined. A library of spectra of 141 vials of dantrolene from 4 lots were found to contain 3 separate groups, also suggesting that different vials contain different materials.

Quality Variations in Thyrotropin Alfa.

Thyrotropin alfa is a heterodimeric glycoprotein containing human thyroid stimulating hormone (TSH). It is used as an adjunctive diagnostic tool for serum thyroglobulin (Tg) testing with or without radioiodine imaging in the follow-up of patients with well-differentiated thyroid cancer who have previously undergone thyroidectomy. Inter-lot variability in the Fourier transform near-infrared spectra of 30 samples obtained from four separate lots of Thyrogen® was detected in the Drug Quality Study (DQS). The vials fell into two distinct groups (rtst = 0.90, rlim= 0.98, p=0.02). In addition, one vial of the 30 (3%) appeared 4.7 multidimensional SDs from all of the other vials, suggesting that it also represents a different material.

Spectrometric Assessment of Generic and Brand Drug Quality for a Sentinel Screening Network.

The U.S. Food and Drug Administration (FDA) is a worldwide leader among analogous regulatory organizations in other countries. The FDA uses current good manufacturing practices to regulate the processes that produce drugs. Nevertheless, investigative journalists have pointed out problems in the drug supply, and pharmacies are not required to test the drugs they receive. The University of Kentucky Drug Quality Study does perform screening on the sterile injectable drugs that it receives and regularly reports new findings to FDA, practitioners, and the public. A Sentinel Screening Network of academic health systems could provide independent data on drug quality to FDA not available through manufacturers.

Variability in Content of Hydrocortisone Sodium Succinate.

SOLU-CORTEFⓇ Sterile Powder is a type of anti-inflammatory glucocorticoid that contains hydrocortisone sodium succinate as its active ingredient. It can be administered intravenously or intramuscularly, and comes in several packages including 100 mg plain vials without diluent. The diluent, which is part of the ACT-O-VIAL system, contains only Water for Injection and no preservatives. The pH of each formula is adjusted with sodium hydroxide to ensure it falls within the specified range of 7 to 8 after reconstitution. Intralot variability was detected in lot GA6092. Measuring in the PC subspace using just PCs 4, 5 and 6, vial 12 plots 4.2 BEST SDs from the center of the cluster, and vial 7 is 3.7 SDs from the center. Vial 18 appears 3.1 SDS from the center of the cluster (3/18, 17%). Interlot variability was also found in the spectral library (lots GA6092, GK7048, GM6839, GR8925, FL8062, FN6860, FR1914, and FR5098) containing the spectra of 126 hydrocortisone sodium succinate vials.

Spectral Intra-Lot and Inter-Lot Variability in Carfilzomib.

Carfilzomib is a prescription injectable drug approved for use by the FDA as an antineoplastic agent, part of a drug class of medications known as proteasome inhibitors, and used to stop and slow the growth and progression of cancer cells within the body. The drug is approved as an agent to treat multiple myeloma. It is provided as a single-use vial that contains 60 mg of carfilzomib as a sterile, white to off-white lyophilized cake or powder. Intra-lot and inter-lot variability in the spectra of carfilzomib vials was detected in the Drug Quality Study (DQS) using Fourier transform near-infrared spectrometry (FTNIR). One of 12 vials of lot 1143966 manufactured for Onyx Pharmaceuticals, Inc. appeared 4.7 multidimensional standard deviations (SDs) from the other 11 vials in a 3-D space formed by the first 3 principal components, which captured 81% of the total spectral variation. Spectra of 168 vials from 18 lots in the spectral library formed two groups in the 3-D space formed by the first 3 principal components. One group contained 155 vials and the other group contained 13 vials. The 2 groups had different locations and scales using a subcluster detection test at p=0.02.

Assessment of Vecuronium Quality Using Near-Infrared Spectrometry.

This study employed Fourier Transform near-infrared spectrometry to assess the quality of vecuronium bromide, a neuromuscular blocking agent. Spectral data from two lots of vecuronium were collected and analyzed using the BEST metric, principal component analysis (PCA) and other statistical techniques. The results showed that there was variability between the two lots and within each lot. Several outliers in the spectral data suggested potential differences in the chemical composition or sample condition of the vials. The outliers were identified and their spectral features were examined. A total of eight unique outliers were found in the PC space from PCs 1 to 9, so 22% of the total vials were outliers. The study findings suggest that the manufacturing process of vecuronium bromide may have been operating outside of a state of process control. Further investigation is needed to determine the source of these variations and their impact on the safety and efficacy of the drug product.

Tensile fatigue strength and endurance limit of human meniscus.

The knee menisci are prone to mechanical fatigue injury from the cyclic tensile stresses that are generated during daily joint loading. Here we characterize the tensile fatigue behavior of human medial meniscus and investigate the effect of aging on fatigue strength. Test specimens were excised from the medial meniscus of young (under 40 years) and older (over 65 years) fresh-frozen cadaver knees. Cyclic uniaxial tensile loads were applied parallel to the primary circumferential fibers at 70%, 50%, 40%, or 30% of the predicted ultimate tensile strength (UTS) until failure occurred or one million cycles was reached. Equations for fatigue strength (S-N curve) and the probability of fatigue failure (unreliability curves) were created from the measured number of cycles to failure. The mean number of cycles to failure at 70%, 50%, 40%, and 30% of UTS were estimated to be approximately 500, 40000, 340000, and 3 million cycles, respectively. The endurance limit, defined as the tensile stress that can be safely applied for the average lifetime of use (250 million cycles), was estimated to be 10% of UTS (∼1.0 MPa). When cyclic tensile stresses exceeded 30% of UTS (∼3.0 MPa), the probability of fatigue failure rapidly increased. While older menisci were generally weaker and more susceptible to fatigue failures at high-magnitude tensile stresses, both young and older age groups had similar fatigue resistance at low-magnitude tensile stresses. In addition, we found that fatigue failures occurred after the dynamic modulus decreased during cyclic loading by approximately 20%. This experimental study has quantified fundamental fatigue properties that are essential to properly predict and prevent injury in meniscus and other soft fibrous tissues.

Levothyroxine Variations by Process Analytical Technology.

Intra-lot and inter-lot variability in the spectra of levothyroxine was detected in the Drug Quality Study (DQS) using Fourier transform near-infrared spectrometry (FTNIR). Two vials of 12 vials sampled from Athenex lot AFN102 appeared 10.1 and 9.1 SDs from the center of the rest of the vials on the DQS FTNIR screening assay. Spectra of 108 vials from six lots in the library clustered in two groups (p=0.02), suggesting they represent different material.

Variability in Content of Piperacillin and Tazobactam Injection.

Piperacillin and Tazobactam Injection is a combination product consisting of a penicillin-class antibacterial, piperacillin, and a beta-lactamase inhibitor, tazobactam, indicated for the treatment of patients with moderate to severe infections caused by susceptible isolates of bacteria. In the past decade some quality problems have been noted by the US Food and Drug Administration (FDA) with the Apotex Corp. manufacturing. Intra-lot and inter-lot variability in the spectra of Piperacillin and Tazobactam Injection 3.375 g was detected in the Drug Quality Study (DQS) using Fourier transform near-infrared spectrometry (FTNIR). One vial of 6 (17%) sampled from lot AD103008F3 appeared 14.4 multidimensional SDs from the other vials, suggesting that it represents a different material. Spectra of 132 vials from 19 lots in the spectral library contained 4 vials that were outside the group (21.0 SDs using a subcluster detection test), suggesting that the 4 library vials (3%) also contain differing materials.

Spectrometric Results of Process Variations in Dacarbazine.

Intra-lot and inter-lot variability in dacarbazine was detected in the Drug Quality Study (DQS) using Fourier transform near-infrared spectrometry (FTNIR). One vial of six vials sampled from Fresenius Kabi Lot 6125612 appeared 7.8 SDs from the center of the rest of the vials on the DQS FTNIR screening assay. Spectra of 54 vials from six lots in the library clustered in two groups (p=0.02), suggesting they represent different material.

FTNIR Spectrometry of Micafungin Sodium Quality.

Intra-lot and inter-lot variability in the spectra of micafungin was detected in the Drug Quality Study (DQS) using Fourier transform near-infrared spectrometry (FTNIR). Two vials of 6 vials sampled from Fresenius Kabi lot ACP106 appeared 7.9 and 14.0 standard deviations (SDs) from the center of the rest of the vials on the DQS FTNIR screening assay. Spectra of 48 vials from 7 lots in the library showed 2 outliers at 8.3 and 9.8 SDs from the center of the rest of the library, suggesting they represent different material.

Lack of Content Uniformity in MMR Vaccine.

The measles, mumps, and rubella (MMR) vaccine is a vaccine used to prevent measles, mumps, and rubella (German measles). The vaccine is mandated for children to attend public school in nearly all US states. However, measles cases have been increasing in the past decade, and quality problems have recently been noted by the US Food and Drug Administration (FDA) with the vaccine manufacturer. Intra-lot and inter-lot variability in the spectra of MMR (measles, mumps, and rubella) vaccine was detected in the Drug Quality Study (DQS) using Fourier transform near-infrared spectrometry (FTNIR). Six vials of 12 (50%) sampled from Merck lot U006488 appeared 14.5 SDs from the other vials on a subcluster detection test, suggesting that they represent different material. Spectra of 198 vials from 12 lots in the spectral library contained 140 vials in one tight ellipsoidal group, and 58 vials (30%) were outside that group (39.7 SDs using a subcluster detection test), suggesting that the library vials also contain differing materials.

Potential Process Control Issues with Pemetrexed.

Pemetrexed is a folate analog metabolic inhibitor used in treatment of locally advanced or metastatic nonsquamous non-small cell lung cancer and for mesothelioma. Intra-lot and inter-lot variability in the spectra of ALIMTA® was detected in the Drug Quality Study (DQS) using Fourier transform near-infrared spectrometry (FTNIR). One vial of 12 (8%) sampled from lot S20I013A appeared 3.0 multidimensional SDs from the other vials, suggesting that it represents a different material. Consequently, additional spectra from other lots were analyzed. Spectra of 147 vials from 23 lots in the spectral library contained 14 vials that were outside the main group (26.4 SDs using a subcluster detection test), suggesting that the 14 library vials (9.5% of the total) also contain differing materials.

Spectrometric Analysis of Process Variations in Remifentanil.

ULTIVA® (remifentanil hydrochloride) is a sterile, nonpyrogenic, preservative-free, white to off-white lyophilized powder for intravenous (IV) administration after reconstitution and dilution. Each vial contains 1, 2, or 5 mg of remifentanil base; 15 mg glycine; and hydrochloric acid to buffer the solutions to a nominal pH of 3 after reconstitution. ULTIVA® is a µ-opioid agonist with rapid onset and peak effect, and short duration of action. Intra-lot and inter-lot variability in the spectra of ULTIVA® was measured in the Drug Quality Study (DQS) using Fourier transform near-infrared spectrometry (FTNIR). In 6 vials sampled, 1 came from lot 220453F while 5 came from lot 30020BF. The 1 vial sampled from lot 220453F appeared 122 multidimensional SDs from the other vials from lot 30020BF, suggesting that it represents a different formulation or material. Consequently, additional spectra from other lots were analyzed. Spectra of 90 vials from 9 lots in the spectral library contained vials that were outside the main group (50.3 SDs using a subcluster detection test), suggesting that the 35 library vials (39% of the total) contain different materials from the other 55 vials.

FDA Approaches in Monitoring Drug Quality, Forces Impacting the Drug Quality, and Recent Alternative Strategies to Assess Quality in the US Drug Supply.

Since the US Food and Drug Administration (FDA) began monitoring the quality of pharmaceutical manufacturing by enforcing current good manufacturing practices roughly 60 years ago, forces related to the global economy have changed, rendering the task of monitoring quality more difficult. Alternative strategies by groups like Valisure, LLC, and the University of Kentucky Drug Quality Study to monitor the quality of the currently circulated US drug supply through end-product testing and screening have resulted in several concerning findings. Given the successful approaches of identifying quality defects in pharmaceuticals by non-regulatory bodies, and considering the changing landscape and pressures on manufacturing, the FDA, large buying groups, and the US Department of Defense should consider these alternative strategies as a means to augment current regulatory activities.