Qualitative and quantitative analysis of glutathione and related impurities in pharmaceuticals by qNMR.

In this study, an alternative method to compendial analytical procedures with enhanced detection and separation capabilities was validated for the quality assessment of glutathione (GSH) drug substance. The related impurities A, B, C, and D present in GSH drug substance were characterized using a one-dimension proton nuclear magnetic resonance (1D 1H NMR) method on a 600 MHz spectrometer equipped with a liquid nitrogen cryoprobe. Two sample preparations at different pH were optimized to ensure the unambiguous identification of different impurities in the GSH samples. Specifically, impurities A and C in a GSH sample can be tested at pH 3.0, while pH 7.4 is more suitable for testing impurities B and D. The quantitative NMR (qNMR) method was validated following International Council for Harmonisation (ICH) guidelines. The limit of detection (LOD) was less than 0.1% wt for an individual impurity, and the limit of quantitation (LOQ) ranged from 0.14 to 0.24% wt, using about 14 min experimental time per spectrum. Following validation, the qNMR method was applied to assess different commercial GSH bulk substance samples, an in-house compounded GSH drug product, and a GSH dietary supplement product. The method was also applied to monitor GSH degradation (hydrolysis and oxidation) over time to provide quantitative information on GSH degradation and stability. The results suggest that the qNMR method can serve as a highly specific and efficient orthogonal tool for assessing the quality of GSH pharmaceuticals, providing both qualitative and quantitative information on GSH and its related impurities A-D.

Decoding Complexity in Synthetic Oligonucleotides: Unraveling Coeluting Isobaric Impurity Ions by High Resolution Mass Spectrometry.

Analyzing coeluting impurities with similar masses in synthetic oligonucleotides by liquid chromatography-mass spectrometry (LC-MS) poses challenges due to inadequate separation in either dimension. Herein, we present a direct method employing fully resolved isotopic envelopes, enabled by high resolution mass spectrometry (HRMS), to identify and quantify isobaric impurity ions resulting from the deletion or addition of a uracil (U) or cytosine (C) nucleotide from or to the full-length sequence. These impurities may each encompass multiple sequence variants arising from various deletion or addition sites. The method utilizes a full or targeted MS analysis to measure accurate isotopic distributions that are chemical formula dependent but nucleotide sequence independent. This characteristic enables the quantification of isobaric impurity ions involving sequence variants, a capability typically unavailable in sequence-dependent MS/MS methods. Notably, this approach does not rely on standard curves to determine isobaric impurity compositions in test samples; instead, it utilizes the individual isotopic distributions measured for each impurity standard. Moreover, in cases where specific impurity standards are unavailable, the measured isotopic distributions can be adequately replaced with the theoretical distributions (calculated based on chemical formulas of standards) adjusted using experiment-specific correction factors. In summary, this streamlined approach overcomes the limitations of LC-MS analysis for coeluting isobaric impurity ions, offering a promising solution for the in-depth profiling of complex impurity mixtures in synthetic oligonucleotide therapeutics.

Old Polymorph, New Technique: Assessing Ritonavir Crystallinity Using Low-Frequency Raman Spectroscopy.

Two decades ago, postmarket discovery of a second crystal form of ritonavir with lower solubility had major implications for drug manufacturers and patients. Since then, ritonavir has been reformulated via the hot-melt-extrusion process in an amorphous form. Here, quantitative low- and mid-frequency Raman spectroscopy methods were developed to characterize polymorphs, form I and form II, in commercial ritonavir 100 mg oral tablets as an alternate analysis approach compared to X-ray powder diffraction (XRPD). Crystallization in three lots of ritonavir products obtained from four separate manufacturers was assessed after storage under accelerated conditions at 40 °C and 75% relative humidity (RH). Results were compared with quantitative XRPD methods developed and validated according to ICH Q2 (R1) guidelines. In a four-week open-dish study, form I crystallization occurred in two of the four products and form II crystallization was detected in another ritonavir product. The limits of detection for XRPD, low-frequency Raman (LFR), and mid-frequency Raman (MFR) were determined to be 0.7, 0.8, and 0.5% for form I and 0.6, 0.6, and 1% for form II, respectively. Root-mean-squared-error of predictions were 0.6-1.0 and 0.6-2.5% for LFR- and MFR-based partial least-squares models. Further, ritonavir polymorphs could also be identified and detected directly from ritonavir tablets using transmission LFR. In summary, LFR was applied for the assessment of polymorphism in real-world samples. While providing analytical performance similar to conventional techniques, LFR reduced the single measurement time from 66 min (XRPD) to 10 s (LFR) without the need for tedious sample preparation procedures.

Scanning Electron-Raman Cryomicroscopy for Characterization of Nanoparticle-Albumin Drug Products.

Nanomaterials have expanded the use of active pharmaceutical ingredients by improving efficacy, decreasing toxicity, and facilitating targeted delivery. To systematically achieve this goal, nanomaterial-containing drugs need to be manufactured with precision in attributes such as size, morphology, surface chemistry, and composition. Their physicochemical characterization is essential as their attributes govern pharmacokinetics yet can be challenging due to the nature of many nanomaterial-based formulations unless advanced sample fixation and in vitro characterization methods are utilized. Here, different cryogenic and other fixation strategies were assessed, and a novel physicochemical characterization method was developed using scanning electron Raman cryo-microscopy (SERCM). A complex nanoparticle albumin bound paclitaxel (nab-paclitaxel) formulation was chosen as a model drug. Plunge freezing (PF), high pressure freezing (HPF), freeze substitution (FS), and membrane filtration were compared for their influence on size and morphology measurements, and formulation-based variations were quantified. SERCM was introduced as a multiattribute physicochemical characterization platform, and the composition of nanoparticles was confirmed as albumin-paclitaxel complexes. By coupling image-based quantitative analysis with chemical analysis, SERCM has the potential to pave the way for the development of comprehensive tools for assessing injectable and ophthalmic nanomaterial-containing drugs in their native-like state.

A top-down spectroscopic approach for correlating coating thickness distributions with the dissolution profiles of enterically coated pellets.

Pharmaceutical dosage forms such as tablets and capsules are often coated with a functional polymer to modify the drug release. To obtain the drug release profiles, ensure quality control and predict in-vivo performance, dissolution studies are performed. However, dissolution tests are time-consuming, sample destructive and do not readily allow for at-line or in-line characterization. Rapid assessment of functional coatings is essential for products where a single capsule is comprised of hundreds of functionally-coated pellets and the collective drug release kinetics of the entire capsule depends on contributions from each pellet. Here, single Raman measurements were used to evaluate the coating thickness distributions of a dosage form comprised of small, functionally-coated pellets in capsules. First, the composition and physicochemical properties of pellets were characterized by multivariate analysis assisted Raman mapping of pellet cross-sections. Second, a method of collecting single Raman spectrum with spectral contributions from the coating and API layers was developed and optimized to estimate the thickness of coatings. The coating thicknesses obtained from single Raman measurements of pellets in each capsule revealed thickness distributions that correlated with the dissolution profiles (capsules with one distribution had single stage release and capsules with two distributions had a two-stage release). Finally, an unsupervised multivariate analysis method was demonstrated as a rapid and efficient way to correlate dissolution profiles of enterically coated pellets. In summary, this study presents a non-destructive and rapid characterization method for assessing coating thickness and has the potential to be applied in process analytical technologies to ensure coating uniformity and predict product dissolution rate performance.

Development and validation of a quantitative proton NMR method for the analysis of pregnenolone.

Pregnenolone (PREG) is an endogenous steroid frequently sold as an over-the-counter dietary supplement touted to promote neurological and immunological health. While the PREG dietary supplement is added to the diet for health benefits, there are no FDA approved PREG drugs. However, compounded PREG drug products are available to U.S. patients. The FDA works with state regulatory authorities on the oversight of compounding activities, including developing 503A and 503B lists of bulk substances that compounders are permitted to use. PREG is one of the substances publicly nominated to be included on the 503B list. Compounded hormone therapies such as those using PREG are of interest given the lack of standardization in compounded drug products which may increase the possibility of underdosing, overdosing, or contamination. However, no USP monograph currently exists to evaluate the quality of PREG drug substance or product. To address knowledge gaps and assist in quality control, a simple and rapid quantitative proton nuclear magnetic resonance spectroscopy (qNMR) method for the identification and assay of PREG in different types of PREG products was developed and validated. PREG samples were characterized using 1D 1H and 2D 1H-13C HSQC NMR spectra. The qNMR assay method (taking approximately 10 min per NMR spectrum) was validated for precision, accuracy, specificity, robustness and linearity per ICH Q2(R1) guidance. The method was validated in a range from 0.032 to 3.2 mg/mL. As a proof of concept, seven PREG bulk substance samples, three tablet and two capsule PREG dietary supplements were assessed by the qNMR analytical procedure. NMR data from all tested samples met the expected criteria for identification and assay. The results demonstrate the potential of qNMR for the quality assessment of different types of PREG samples.

Tandem mass spectrometric sequence characterization of synthetic thymidine-rich oligonucleotides.

Tandem mass spectrometry (MS/MS) can provide direct and accurate sequence characterization of synthetic oligonucleotide drugs, including modified oligonucleotides. Multiple factors can affect oligonucleotide MS/MS sequencing, including the intrinsic properties of oligonucleotides (i.e., nucleotide composition and structural modifications) and instrument parameters associated with the ion activation for fragmentation. In this study, MS/MS sequencing of a thymidine (T)-rich and phosphorothioate (PS)-modified DNA oligonucleotide was investigated using two fragmentation techniques: trap-type collision-induced dissociation ("CID") and beam-type CID also termed as higher-energy collisional dissociation ("HCD"), preceded by a hydrophilic interaction liquid chromatography (HILIC) separation. A low to moderate charge state (-4), which predominated under the optimized HILIC-MS conditions, was selected as the precursor ion for MS/MS analysis. Comparison of the two distinctive ion activation mechanisms on the same precursor demonstrated that HCD was superior to CID in promoting higher sequence coverage and analytical sensitivity in sequence elucidation of T-rich DNA oligonucleotides. Specifically, HCD provided more sequence-defining fragments with higher fragment intensities than CID. Furthermore, the direct comparison between unmodified and PS-modified DNA oligonucleotides demonstrated a loss of MS/MS fragmentation efficiency by PS modification in both CID and HCD approaches, and a resultant reduction in sequence coverage. The deficiency in PS DNA sequence coverage observed with single collision energy HCD, however, was partially recovered by applying HCD with multiple collision energies. Collectively, this work demonstrated that HCD is advantageous to MS/MS sequencing of T-rich PS-modified DNA oligonucleotides.

Development of In Vitro Dissolution Testing Methods to Simulate Fed Conditions for Immediate Release Solid Oral Dosage Forms.

In vitro dissolution testing is widely used to mimic and predict in vivo performance of oral drug products in the gastrointestinal (GI) tract. This literature review assesses the current in vitro dissolution methodologies being employed to simulate and predict in vivo drug dissolution under fasted and fed conditions, with emphasis on immediate release (IR) solid oral dosage forms. Notable human GI physiological conditions under fasted and fed states have been reviewed and summarized. Literature results showed that dissolution media, mechanical forces, and transit times are key dissolution test parameters for simulating specific postprandial conditions. A number of biorelevant systems, including the fed stomach model (FSM), GastroDuo device, dynamic gastric model (DGM), simulated gastrointestinal tract models (TIM), and the human gastric simulator (HGS), have been developed to mimic the postprandial state of the stomach. While these models have assisted in expanding physiological relevance of in vitro dissolution tests, in general, these models lack the ability to fully replicate physiological conditions/processes. Furthermore, the translatability of in vitro data to an in vivo system remains challenging. Additionally, physiologically based pharmacokinetic (PBPK) modeling has been employed to evaluate the effect of food on drug bioavailability and bioequivalence. Here, we assess the current status of in vitro dissolution methodologies and absorption PBPK modeling approaches to identify knowledge gaps and facilitate further development of in vitro dissolution methods that factor in fasted and fed states. Prediction of in vivo drug performance under fasted and fed conditions via in vitro dissolution testing and modeling may potentially help efforts in harmonizing global regulatory recommendations regarding in vivo fasted and fed bioequivalence studies for solid oral IR products.

An In Vitro Dissolution Method for Testing Extended-Release Tablets Under Mechanical Compression and Sample Friction.

The release and dissolution of an active pharmaceutical ingredient (API) from the solid oral formulation into the gastrointestinal (GI) tract is critical for the drug's absorption into systemic circulation. Extended-release (ER) solid oral dosage forms are normally subjected to physical shear and grinding forces as well as pressure exerted by peristaltic movements when passing through the GI tract. The complex physical contraction and sample friction exerted by the GI tract are not simulated well by compendial dissolution methods. These limitations render traditional in vitro dissolution testing unable to discriminate and predict a product's in vivo performance. The objective of this study was to develop a dissolution method that better simulates the GI environment that products are subject to when taken by patients. A newly designed Mechanical Apparatus under GI Conditions (MAGIC) was assembled with a dissolution platform and mechanical capabilities to allow in vitro dissolution testing under sample contractions and friction. The dissolution platform, with medium flow-through configuration, was manufactured by 3D printing. A 60 mg polymer matrix-based ER nifedipine product was tested. To simulate GI physiological conditions during the dissolution testing, the flow rate of the medium, and a combination of mechanical compression with rotation induced sample friction at various rotation frequencies were explored. The polymer matrix-based nifedipine ER formulation used here failed its controlled release functionality in the simulated GI environment under mechanical compression and sample friction. The results showed that the MAGIC system, with flow-through configuration under compression and sample friction, has advantages over compendial methods in testing ER solid oral formulations.

In Vitro Analysis of N-Nitrosodimethylamine (NDMA) Formation From Ranitidine Under Simulated Gastrointestinal Conditions.

Importance: A publication reported that N-nitrosodimethylamine (NDMA), a probable human carcinogen, was formed when ranitidine and nitrite were added to simulated gastric fluid. However, the nitrite concentrations used were greater than the range detected in acidic gastric fluid in prior clinical studies. Objective: To characterize NDMA formation following the addition of ranitidine to simulated gastric fluid using combinations of fluid volume, pH levels, and nitrite concentrations, including physiologic levels. Design, Setting, and Participants: One 150-mg ranitidine tablet was added to 50 or 250 mL of simulated gastric fluid with a range of nitrite concentrations from the upper range of physiologic (100 µmol/L) to higher concentrations (10 000 µmol/L) with a range of pH levels. NDMA amounts were assessed with a liquid chromatography-mass spectrometry method. Main Outcomes and Measures: NDMA detected in simulated gastric fluid 2 hours after adding ranitidine. Results: At a supraphysiologic nitrite concentration (ie, 10 000 µmol/L), the mean (SD) amount of NDMA detected in 50 mL simulated gastric fluid 2 hours after adding ranitidine increased from 222 (12) ng at pH 5 to 11 822 (434) ng at pH 1.2. Subsequent experiments with 50 mL of simulated gastric fluid at pH 1.2 with no added nitrite detected a mean (SD) of 22 (2) ng of NDMA, which is the background amount present in the ranitidine tablets. Similarly, at the upper range of physiologic nitrite (ie, 100 µmol/L) or at nitrite concentrations as much as 50-fold greater (1000 or 5000 µmol/L) only background mean (SD) amounts of NDMA were observed (21 [3] ng, 24 [2] ng, or 24 [3] ng, respectively). With 250 mL of simulated gastric fluid, no NDMA was detected at the upper physiologic range (100 µmol/L) or 10-fold physiologic (1000 µmol/L) nitrite concentrations, while NDMA was detected (mean [SD] level, 7353 [183] ng) at a 50-fold physiologic nitrite concentration (5000 µmol/L). Conclusions and Relevance: In this in vitro study of ranitidine tablets added to simulated gastric fluid with different nitrite concentrations, ranitidine conversion to NDMA was not detected until nitrite was 5000 µmol/L, which is 50-fold greater than the upper range of physiologic gastric nitrite concentrations at acidic pH. These findings suggest that ranitidine is not converted to NDMA in gastric fluid at physiologic conditions.

Evaluation of the Physicochemical Properties of the Iron Nanoparticle Drug Products: Brand and Generic Sodium Ferric Gluconate.

Complex iron nanoparticle-based drugs are one of the oldest and most frequently administered classes of nanomedicines. In the US, there are seven FDA-approved iron nanoparticle reference drug products, of which one also has an approved generic drug product (i.e., sodium ferric gluconate (SFG)). These products are indicated for the treatment of iron deficiency anemia and are administered intravenously. On the molecular level, iron nanomedicines are colloids composed of an iron oxide core with a carbohydrate coating. This formulation makes nanomedicines more complex than conventional small molecule drugs. As such, these products are often referred to as nonbiological complex drugs (e.g., by the nonbiological complex drugs (NBCD) working group) or complex drug products (e.g., by the FDA). Herein, we report a comprehensive study of the physiochemical properties of the iron nanoparticle product SFG. SFG is the single drug for which both an innovator (Ferrlecit) and generic product are available in the US, allowing for comparative studies to be performed. Measurements focused on the iron core of SFG included optical spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), X-ray powder diffraction (XRPD), 57Fe Mössbauer spectroscopy, and X-ray absorbance spectroscopy (XAS). The analysis revealed similar ferric-iron-oxide structures. Measurements focused on the carbohydrate shell comprised of the gluconate ligands included forced acid degradation, dynamic light scattering (DLS), analytical ultracentrifugation (AUC), and gel permeation chromatography (GPC). Such analysis revealed differences in composition for the innovator versus the generic SFG. These studies have the potential to contribute to future quality assessment of iron complex products and will inform on a pharmacokinetic study of two therapeutically equivalent iron gluconate products.

Through-container quantitative analysis of hand sanitizers using spatially offset Raman spectroscopy.

The COVID-19 pandemic created an increased demand for hygiene supplies such as hand sanitizers. In response, a large number of new domestic or imported hand sanitizer products entered the US market. Some of these products were later found to be out of specification. Here, to quickly assess the quality of the hand sanitizer products, a quantitative, through-container screening method was developed for rapid and non-destructive screening. Using spatially offset Raman spectroscopy (SORS) and support vector regression (SVR), active ingredients (e.g., type of alcohol) of 173 commercial and in-house products were identified and quantified regardless of the container material or opacity. Alcohol content in hand sanitizer formulations were predicted with high accuracy [Formula: see text] using SVR and [Formula: see text] of the substandard test samples were identified. In sum, a SORS-SVR method was developed and used for testing medical countermeasures used against COVID-19, demonstrating a potential for high-volume testing during public health threats.

QCM Sensor Arrays, Electroanalytical Techniques and NIR Spectroscopy Coupled to Multivariate Analysis for Quality Assessment of Food Products, Raw Materials, Ingredients and Foodborne Pathogen Detection: Challenges and Breakthroughs.

Quality checks, assessments, and the assurance of food products, raw materials, and food ingredients is critically important to ensure the safeguard of foods of high quality for safety and public health. Nevertheless, quality checks, assessments, and the assurance of food products along distribution and supply chains is impacted by various challenges. For instance, the development of portable, sensitive, low-cost, and robust instrumentation that is capable of real-time, accurate, and sensitive analysis, quality checks, assessments, and the assurance of food products in the field and/or in the production line in a food manufacturing industry is a major technological and analytical challenge. Other significant challenges include analytical method development, method validation strategies, and the non-availability of reference materials and/or standards for emerging food contaminants. The simplicity, portability, non-invasive, non-destructive properties, and low-cost of NIR spectrometers, make them appealing and desirable instruments of choice for rapid quality checks, assessments and assurances of food products, raw materials, and ingredients. This review article surveys literature and examines current challenges and breakthroughs in quality checks and the assessment of a variety of food products, raw materials, and ingredients. Specifically, recent technological innovations and notable advances in quartz crystal microbalances (QCM), electroanalytical techniques, and near infrared (NIR) spectroscopic instrument development in the quality assessment of selected food products, and the analysis of food raw materials and ingredients for foodborne pathogen detection between January 2019 and July 2020 are highlighted. In addition, chemometric approaches and multivariate analyses of spectral data for NIR instrumental calibration and sample analyses for quality assessments and assurances of selected food products and electrochemical methods for foodborne pathogen detection are discussed. Moreover, this review provides insight into the future trajectory of innovative technological developments in QCM, electroanalytical techniques, NIR spectroscopy, and multivariate analyses relating to general applications for the quality assessment of food products.

A Cautionary Tale: Quantitative LC-HRMS Analytical Procedures for the Analysis of N-Nitrosodimethylamine in Metformin.

A private testing laboratory reported in a Citizen Petition (CP) to FDA that 16 of 38 metformin drug products they tested had N-nitrosodimethyl amine (NDMA) amounts above the allowable intake (AI) of 96 ng/day. Because the FDA had been monitoring drugs for nitrosamines, orthogonal analytical procedures had been developed, validated and applied to detect the following nitrosamines in metformin drug products (if present): (i) NDMA (with a dedicated method) or (ii) NDMA (with a second confirmatory method), N-nitroso-diethylamine (NDEA), N-ethyl-N-nitroso-2-propanamine (NEIPA), N-nitroso-diisopropylamine (NDIPA), N-nitroso-di-n-propylamine (NDPA), N-nitroso-methylphenylamine (NMPA), N-nitroso-di-n-butylamine (NDBA) and N-nitroso-N-methyl-4-aminobutyric acid (NMBA). In contrast to the private laboratory results, FDA testing on the same set of 38 samples with orthogonal procedures observed amounts over the AI in only 8 of the 38 products and generally observed lower values than reported by the private testing laboratory. As described here, the investigation into the cause of the discrepancy revealed that N,N-dimethylformamide (DMF) can interfere with NDMA measurements. The data showed that the use of sufficient mass accuracy in the data acquisition and appropriate mass tolerance setting in the data processing to assure the selectivity of mass spectrometry measurements of NDMA in the presence of co-eluting DMF was necessary to prevent overestimation of the level of NDMA in metformin drug products. Overall, care should be taken to assure the necessary specificity in analytical procedures for adequate assessment of the nitrosamine level in drug products that also contain DMF or other potential interfering substances.

An NMR Protocol for In Vitro Paclitaxel Release from an Albumin-Bound Nanoparticle Formulation.

The paclitaxel protein-bound particles for injectable suspension (marketed under the brand name Abraxane®) contains nanosized complexes of paclitaxel and albumin. The molecular interaction between paclitaxel and albumin within the higher-order nanostructure is analytically challenging to assess, as is any correlation of differences to differences in therapeutic effect. However, because the higher-order nanostructures may affect the paclitaxel release, a suitable in vitro assay to detect potential differences in paclitaxel release between comparator lots and products is desirable. Herein, solution NMR spectroscopy with a T2-filtering technique was developed to detect paclitaxel signal while suppressing albumin signals to follow the released paclitaxel in the NMR tube upon dilution. The non-invasive nature of NMR allows for precise measurement of a full range of dilution-induced drug release percentage from 14 to 92% without any sample extraction. The critical concentration of the drug product (DP) at 50% of release was 0.63 ± 0.04 mg/mL in PBS buffer. In addition, 2D diffusion ordered NMR spectroscopy (DOSY) results revealed that the released paclitaxel experiencing slightly slowed diffusion rates than free paclitaxel, which was attributed to paclitaxel in equilibrium with albumin-bound states. Collectively, the dilution-based NMR method offered an analytical approach to investigate physicochemical attributes of complex injectable products with minimal needed sample preparation and perturbation to nanoparticle formulation.

Nifedipine Release From Extended-Release Solid Oral Formulations Using In Vitro Dissolution Testing Under Simulated Gastrointestinal Compression.

Drug release plays a critical role in defining bioavailability for an extended release solid oral drug products and predictive dissolution tests are desired to establish clinically relevant quality standards for batch release. The objective of this study focuses on exploring the possible impacts of 1 gastrointestinal (GI) parameter for 1 drug: simulated GI contractions on nifedipine release (in 2 extended release solid oral formulations). The 60 mg nifedipine osmotic pump product A, and polymer matrix-based products B and C were examined in the study. An in-house dissolution system was used to simulate various levels of GI contractions on tested samples, and to monitor changes of sample mechanical properties during dissolution testing. The results show that the polymer matrix-based formulation failed to provide controlled release when simulated GI contraction was above 100 g of force. The method may be useful for polymer matrix-based products to assess potential formulation-related interactions with the GI tract during in vivo drug dissolution.

Raman mapping of fentanyl transdermal delivery systems with off-label modifications.

Raman mapping is a powerful and emerging tool in characterization of pharmaceuticals and provides non-destructive chemical and structural identification with minimal sample preparation. One pharmaceutical form that is suitable but has not been studied in-depth with Raman mapping is transdermal delivery systems (TDS). TDS are dosage forms designed to deliver a therapeutically effective amount of active pharmaceutical ingredient (API) across a patient's skin. To enhance drug delivery through the skin, the API in the formulation is often close to a saturated or supersaturated state. Thus, improper use or off-label modifications can lead to occurrence of unwanted API changes, specifically, crystallization over time. Here, off-label modifications were mimicked on a set of fentanyl drug-in-adhesive TDS sold on the U.S. market by four different manufacturers via die cutting, and then the die cut TDS were investigated through confocal Raman mapping for structural and chemical changes. Using Multivariate Curve Resolution (MCR), not only was morphological and chemical characterization of transdermal systems provided, but also fentanyl crystals in certain products due to off-label modifications were identified. The chemometric model used in analysis of Raman maps allowed precise identification of fentanyl as the crystalline material as confirmed by the hit-quality-index correlation of component spectra from the chemometric model with library spectra of a fentanyl reference standard. The results show that confocal Raman mapping with MCR can be utilized in assessing pharmaceutical quality of TDS. This method has the potential to be widely used in characterization of such systems as an alternative to existing techniques.

Effects of Dissolution Medium pH and Simulated Gastrointestinal Contraction on Drug Release From Nifedipine Extended-Release Tablets.

In contrast to nifedipine matrix-based extended-release dosage forms, the osmotic pump drug delivery systems have a zero-order drug release independent of external variables such as pH, agitation rate, and dissolution media. The objective of this study focuses on the in vitro evaluation of the mechanical properties of osmotic pump and polymer matrix-based formulations in dissolution media, and the potential impacts that media pH and simulated gastrointestinal contraction have on drug release. Two strengths of osmotic pump product A and polymer matrix-based product B were used in this study. An in-house system was developed with the capability of applying mechanical compression and monitoring mechanical properties of sample during dissolution testing. A United States Pharmacopeia or an in-house apparatus was used for dissolution testing under various conditions. Compared to the product A, the mechanical properties of the product B change significantly at various pHs and mechanical compressions. The results suggest that polymer matrix-based products bear a risk of formulation-related interactions with the gastrointestinal tract during in vivo drug dissolution, especially in the case of concomitant pH and gastric contractile changes. Modified dissolution testing devices may help formulation scientists in product development and provide regulatory agencies with an additional metric for quality assurance of drug products.

Quantitative Raman assays for on-site analysis of stockpiled drugs.

We present a rapid Raman assay for on-site analysis of stockpiled drugs in aqueous solution. This approach was tested on Tamiflu (oseltamivir phosphate). Tamiflu is a drug approved by the FDA for treatment of influenza and is the most common antiviral included in stockpiles for use in the event of a national emergency. Rapid assays were performed on three concentrations (30, 45, and 75 mg) of oseltamivir using three different portable & handheld Raman instruments. PLS regression models were developed to establish a calibration curve and applied to the Tamiflu samples. Raman assay values were compared against the standard HPLC assay to demonstrate the viability of this approach, yielding an average assay value within 0.3% of that obtained from the HPLC analysis for the 35 different capsules analyzed. The Raman method demonstrates the potential for rapid screening of stockpiled pharmaceuticals on-site using portable Raman instrumentation and readily available consumables for sample preparation. In addition to routine screening to ensure product quality past the expiration date, this approach could also be used to assist in rapid deployment of such medications in the case of a national emergency.

Screening of unapproved drugs using portable Raman spectroscopy.

We present a four-step screening approach for unapproved drugs. The screening approach is both qualitative and quantitative in design in order to determine if the sample under study contains the correct and acceptable amount of the declared active pharmaceutical ingredient. Four commercially-available unapproved antibiotic and antiviral drugs were used in this study. Out of the 40 individual samples tested, 100% of the samples matched for the declared active pharmaceutical ingredient with no false positives. Following this qualitative identification step, a quantitative assay was used to determine the potency of the product. The assay involves dissolving the sample in water and using a partial least squares model to predict the potency of the product. The average Raman potency results for the four products tested were compared with chromatographic reference methods and the spectroscopic data were found to be within ∼1-6% of those obtained with the reference method for the four products tested. The results indicate that aqueous-based Raman assays may be a suitable field-deployable alternative to traditional techniques run in a laboratory environment.