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Mohan S, Li Y, Chu K, De La Paz L, Sperger D, Shi B, Foti C, Rucker V, Lai C. Integrative Salt Selection and Formulation Optimization: Perspectives of Disproportionation and Microenvironmental pH Modulation. Mol Pharm 2024; 21:2590-2605. [PMID: 38656981 DOI: 10.1021/acs.molpharmaceut.4c00166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
We report a novel utilization of a pH modifier as a disproportionation retardant in a tablet formulation. The drug molecule of interest has significant bioavailability challenges that require solubility enhancement. In addition to limited salt/cocrystal options, disproportionation of the potential salt(s) was identified as a substantial risk. Using a combination of Raman spectroscopy with chemometrics and quantitative X-ray diffraction in specially designed stress testing, we investigated the disproportionation phenomena. The learnings and insight drawn from crystallography drove the selection of the maleate form as the target API. Inspired by the fumarate form's unique stability and solubility characteristics, we used fumaric acid as the microenvironmental pH modulator. Proof-of-concept experiments with high-risk (HCl) and moderate-risk (maleate) scenarios confirmed the synergistic advantage of fumaric acid, which interacts with the freebase released by disproportionation to form a more soluble species. The resultant hemifumarate helps maintain the solubility at an elevated level. This work demonstrates an innovative technique to mediate the solubility drop during the "parachute" phase of drug absorption using compendial excipients, and this approach can potentially serve as an effective risk-mitigating strategy for salt disproportionation.
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Affiliation(s)
- Shikhar Mohan
- Gilead Sciences, Inc., Foster City, California 94404, United States
| | - Yi Li
- Gilead Sciences, Inc., Foster City, California 94404, United States
| | - Kevin Chu
- Velexi Corporation, Burlingame, California 94010, United States
| | | | - Diana Sperger
- Gilead Sciences, Inc., Foster City, California 94404, United States
| | - Bing Shi
- Gilead Sciences, Inc., Foster City, California 94404, United States
| | - Chris Foti
- Gilead Sciences, Inc., Foster City, California 94404, United States
| | - Victor Rucker
- Gilead Sciences, Inc., Foster City, California 94404, United States
| | - Chiajen Lai
- Gilead Sciences, Inc., Foster City, California 94404, United States
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Li J, Wang Y, Yu D. Effects of Additives on the Physical Stability and Dissolution of Polymeric Amorphous Solid Dispersions: a Review. AAPS PharmSciTech 2023; 24:175. [PMID: 37603110 DOI: 10.1208/s12249-023-02622-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 07/20/2023] [Indexed: 08/22/2023] Open
Abstract
Polymeric amorphous solid dispersion (ASD) is a popular approach for enhancing the solubility of poorly water-soluble drugs. However, achieving both physical stability and dissolution performance in an ASD prepared with a single polymer can be challenging. Therefore, a secondary excipient can be added. In this paper, we review three classes of additives that can be added internally to ASDs: (i) a second polymer, to form a ternary drug-polymer-polymer ASD, (ii) counterions, to facilitate in situ salt formation, and (iii) surfactants. In an ASD prepared with a combination of polymers, each polymer exerts a unique function, such as a stabilizer in the solid state and a crystallization inhibitor during dissolution. In situ salt formation in ASD usually leads to substantial increases in the glass transition temperature, contributing to improved physical stability. Surfactants can enhance the wettability of ASD particles, thereby promoting rapid drug release. However, their potential adverse effects on physical stability and dissolution, resulting from enhanced molecular mobility and competitive molecular interaction with the polymer, respectively, warrant careful consideration. Finally, we discuss the impact of magnesium stearate and inorganic salts, excipients added externally upon downstream processing, on the solid-state stability as well as the dissolution of ASD tablets.
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Affiliation(s)
- Jinghan Li
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota, 55455, USA
| | - Yihan Wang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, 20 North Pine Street, Baltimore, Maryland, 21201, USA
| | - Dongyue Yu
- Pharmaceutical Candidate Optimization, Bristol Myers Squibb, Route 206 and Province Line Road, Princeton, New Jersey, 08540, USA.
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Van Duong T, Diab S, Hodnett NS, Taylor LS. Kinetic Barriers to Disproportionation of Salts of Weakly Basic Drugs. Mol Pharm 2023; 20:3886-3894. [PMID: 37494545 DOI: 10.1021/acs.molpharmaceut.2c01034] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Disproportionation is a major issue in formulations containing salts of weakly basic drugs. Despite considerable interest in risk assessment approaches for disproportionation, the prediction of salt-to-base conversion remains challenging. Recent studies have highlighted several confounding factors other than pHmax that appear to play an important role in salt disproportionation and have suggested that kinetic barriers need to be considered in addition to the thermodynamic driving force when assessing the risk of a salt to undergo conversion to parent free base. Herein, we describe the concurrent application of in situ Raman spectroscopy and pH monitoring to investigate the disproportionation kinetics of three model salts, pioglitazone hydrochloride, sorafenib tosylate, and atazanavir sulfate, in aqueous slurries. We found that even for favorable thermodynamic conditions (i.e., pH ≫ pHmax), disproportionation kinetics of the salts were very different despite each system having a similar pHmax. The importance of free base nucleation kinetics was highlighted by the observation that the disproportionation conversion time in the slurries showed the same trend as the free base nucleation induction time. Pioglitazone hydrochloride, with a free base induction time of <1 min, rapidly converted to the free base in slurry experiments. In contrast, atazanavir sulfate, where the free base induction time was much longer, took several hours to undergo disproportionation in the slurry for pH ≫ pHmax. Additionally, we altered an established thermodynamically based modeling framework to account for kinetic effects (representing the nucleation kinetic barrier) to estimate the solid-state stability of salt formulations. In conclusion, a solution-based thermodynamic model is mechanistically appropriate to predict salt disproportionation in a solid-state formulation, when kinetic barriers are also taken into consideration.
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Affiliation(s)
- Tu Van Duong
- Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, Indiana47907, United States
| | - Samir Diab
- GlaxoSmithKline, Park Road, Ware, SG12 0DP, U.K
| | - Neil S Hodnett
- GlaxoSmithKline, Gunnels Wood Road, Stevenage, SG1 2NY, U.K
| | - Lynne S Taylor
- Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, Indiana47907, United States
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Weldeab AO, McElderry JD, Lin Y. The Effect of In-Situ-Generated Moisture on Disproportionation of Pharmaceutical Salt. Mol Pharm 2023; 20:561-571. [PMID: 36524757 DOI: 10.1021/acs.molpharmaceut.2c00765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Pharmaceutical salts are ubiquitously present in the market given their benefits in optimizing the critical properties of an active pharmaceutical ingredient (API). Achieving these benefits requires careful selection and understanding of the salt form of choice. Stability is especially critical here, as salts are susceptible to disproportionation. Several studies have shown the impact of moisture on disproportionation, with more focus on external humidity (moisture coming from outside the system). This work, on the other hand, is systematically designed to study the impact of moisture generated in situ (moisture produced within the system). To that end, an in-house developed compound 1 was selected as our salt API, and its disproportionation was studied in blends (binary and prototype) with hydrated model excipient─trisodium phosphate dodecahydrate (TSPD). TSPD possesses 12 water molecules, which could get released when triggered with enough energy (confirmed by thermogravimetric analysis and humidity studies). As a control for this study, similar blends were prepared with anhydrous trisodium phosphate (TSP), which has comparable properties to TSPD but lacks water. Overall, significant disproportionation was observed in TSPD blends exposed to 40 °C or 70 °C in a closed system; while no disproportionation was observed when the system was left open due to the escape of the moisture generated in situ. The API also remained intact for the blends with anhydrous TSP, as expected. Meanwhile, stressing at 40 °C/75%RH condition resulted in significant disproportionation for both TSPD and TSP blends due to the exposure to external humidity. Hydrated excipients are normally used in drug development, and this work stresses the need for probing the impact from within the system when such excipients are utilized with salt API. This will help fully unravel the overall effect of moisture on the drug, which is relevant downstream when selecting processing conditions, packaging, and so forth.
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Affiliation(s)
- Asmerom O Weldeab
- Small Molecule Drug Product Development, Biogen, 115 Broadway, Cambridge, Massachusetts02142, United States
| | - John-David McElderry
- Analytical Development, Biogen, 115 Broadway, Cambridge, Massachusetts02142, United States
| | - Yiqing Lin
- Small Molecule Drug Product Development, Biogen, 115 Broadway, Cambridge, Massachusetts02142, United States
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Pu YE, Menger R, Tong Z, Gaebele T. Development of an enhanced formulation to minimize pharmacokinetic variabilities of a weakly basic drug compound. Pharm Dev Technol 2022; 27:406-413. [PMID: 35502986 DOI: 10.1080/10837450.2022.2070206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Formulating poorly water soluble, weakly basic drugs with consistent exposure is often a challenge due to pH dependent solubility. When the oral formulation is exposed to different pH ranges in the gastrointestinal (GI) tract, drug precipitation or incomplete dissolution may occur resulting in decreased drug absorption and higher intra-and inter-patient pharmacokinetic variabilities.In the present study, a series of enhanced formulations containing organic acids and/or surfactants were developed and compared with conventional formulations with respect to their in vitro dissolution performance. The formulation containing 5% citric acid and 1% sodium lauryl sulfate (SLS) showed much less variations in dissolution performance at different pH conditions than a conventional formulation. The combination of citric acid and SLS demonstrated a synergistic effect as compared to use of citric acid alone or in combination with PEG4000 as a precipitation inhibitor.When compared with a conventional formulation and a spray-dried amorphous solid dispersion (ASD) formulation in a dog pharmacokinetics study, the enhanced formulation demonstrated the least AUC and Cmax variability between the two gastric pH-controlled groups. In conclusion, an enhanced formulation using a combination of organic acid and surfactant is recommended for weakly basic drug compounds to minimize drug pharmacokinetic variabilities in clinical studies.
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Affiliation(s)
- Yu Elaine Pu
- Oral Product Development, Global Pharmaceutical Sciences, Bristol-Myers Squibb
| | - Robert Menger
- Analytical Chemistry, Chemical Process Development, Bristol-Myers Squibb
| | - Zeen Tong
- Drug Metabolism and Pharmacokinetics, Nonclinical Disposition Assessment, Bristol-Myers Squibb
| | - Tracy Gaebele
- Material Science and Engineering, Global Pharmaceutical Sciences, Bristol-Myers Squibb
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Nie H, Klinzing G, Xu W. A Comparative Study of Applying Backscattering and Transmission Raman Spectroscopy to Quantify Solid-State Form Conversion in Pharmaceutical Tablets. Int J Pharm 2022; 617:121608. [PMID: 35202722 DOI: 10.1016/j.ijpharm.2022.121608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/05/2022] [Accepted: 02/18/2022] [Indexed: 11/18/2022]
Abstract
Selecting appropriate Raman measurement and data processing method are of importance to enable effective quantification of solid form conversions upon processing or storage. Therefore, a comparative evaluation is presented herein on using backscattering and transmission Raman spectroscopy to quantify salt disproportionation in tablet matrices. The second part focuses on different spectra processing approaches and calibration models for quantifications. Finally, samples under different mechanical stresses were comprehensively analyzed using different Raman measurements. Much as transmission Raman spectrometry may provide accuracy on bulk measurements by having large sampling volume, it has the drawback of signal attenuation and may overlook process-induced phase transitions occurring on local regions of tablet surface. To overcome this limitation, backscattering Raman with deliberate subsampling can be used as an orthogonal method to probe the existence of low-level form conversion distributed over a tablet's surface. In the present case, different levels of the form conversions were found at the edge and the center of tablets due to the uneven shear stress distribution invoked during tablet compression. In such a scenario, it would be beneficial to apply deliberate-focused backscattering and transmission Raman spectrometry together as complementary techniques to capture chemical information both locally and within the bulk of the tablet.
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Affiliation(s)
- Haichen Nie
- Center for Materials Science and Engineering, Merck & Co., Inc., 770 Sumneytown Pike, West Point, PA 19486, United States.
| | - Gerard Klinzing
- Pharmaceutical Sciences, Merck & Co., Inc., 126 E. Lincoln Ave, Rahway, NJ 07065, USA
| | - Wei Xu
- Pharmaceutical Sciences, Merck & Co., Inc., 126 E. Lincoln Ave, Rahway, NJ 07065, USA
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Abouselo A, Rance GA, Tres F, Taylor LS, Kwokal A, Renou L, Scurr DJ, Burley JC, Aylott JW. Effect of Excipients on Salt Disproportionation during Dissolution: A Novel Application of In Situ Raman Imaging. Mol Pharm 2021; 18:3247-3259. [PMID: 34399050 DOI: 10.1021/acs.molpharmaceut.1c00119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have employed a bespoke setup combining confocal Raman microscopy and an ultraviolet-visible (UV-Vis) spectroscopy flow cell to investigate the effect of excipients on the disproportionation kinetics of Pioglitazone HCl (PioHCl) in tablets during dissolution. Three binary formulations of PioHCl, containing citric acid monohydrate (CA), lactose monohydrate (LM), or magnesium stearate (MgSt), respectively, were used as models to study the influence of excipients' physicochemical properties on the rate of salt disproportionation kinetics and dissolution performance in different aqueous pH environments. It was found that formulation excipients can induce or prevent salt disproportionation by modulating the microenvironmental pH regardless of the pH of the dissolution media. Incorporating CA in PioHCl tablets preserves the salt form and enhances the dissolution performance of the salt in the acidic medium (pH = 1.2). In contrast, LM and MgSt had a detrimental effect on in vitro drug performance by inducing salt disproportionation in the tablet during dissolution in the same acidic medium. Dissolution in the neutral medium (pH = 6.8) showed rapid formation of the free base upon contact with the dissolution medium. The Raman maps of the cross-sectioned tablets revealed the formation of a shell consisting of the free base around the edge of the tablet. This shell decreased the rate of penetration of the dissolution medium into the tablet, which had significant implications on the release of the API into the surrounding solution, as shown by the UV-vis absorption spectroscopy drug release data. Our findings highlight the utility of the Raman/UV-vis flow cell analytical platform as an advanced analytical technique to investigate the effect of excipients and dissolution media on salt disproportionation in real time. This methodology will be used to enhance our understanding of salt stability studies that may pave the way for more stable multicomponent formulations.
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Affiliation(s)
- Amjad Abouselo
- School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K
| | | | - Francesco Tres
- Department of Industrial and Physical Pharmacy, College of Pharmacy, Purdue University, West Lafayette, Indiana 4790, United States
| | - Lynne S Taylor
- Department of Industrial and Physical Pharmacy, College of Pharmacy, Purdue University, West Lafayette, Indiana 4790, United States
| | - Ana Kwokal
- Platform Technology & Science, GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, U.K
| | - Ludovic Renou
- Platform Technology & Science, GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, U.K
| | - David J Scurr
- School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K
| | - Jonathan C Burley
- School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K
| | - Jonathan W Aylott
- School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K
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How to stop disproportionation of a hydrochloride salt of a very weakly basic compound in a non-clinical suspension formulation. Int J Pharm 2021; 606:120875. [PMID: 34273425 DOI: 10.1016/j.ijpharm.2021.120875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 06/30/2021] [Accepted: 07/07/2021] [Indexed: 11/21/2022]
Abstract
Our objectives were to stabilize a non-clinical suspension for use in toxicological studies and to develop methods to investigate the stability of the formulation in terms of salt disproportionation. The compound under research was a hydrochloride salt of a practically insoluble discovery compound ODM-203. The first of the three formulation approaches was a suspension prepared and stored at room temperature. The second formulation was stabilized by pH adjustment. In the third approach cooling was used to prevent salt disproportionation. 5 mg/mL aqueous suspension consisting of 20 mg/mL PVP/VA and 5 mg/mL Tween 80 was prepared for each of the approaches. The polymer was used as precipitation inhibitor to provide prolonged supersaturation while Tween 80 was used to enhance dissolution and homogeneity of the suspension. The consequences of salt disproportionation were studied by a small-scale in vitro dissolution method and by an in vivo pharmacokinetic study in rats. Our results show that disproportionation was successfully suppressed by applying cooling of the suspension in an ice bath at 2-8 °C. This procedure enabled us to proceed to the toxicological studies in rats. The in vivo study results obtained for the practically insoluble compound showed adequate exposures with acceptable variation at each dose level.
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Kaur N, Suryanarayanan R. Investigating the Influence of Excipients on the Stability of Levothyroxine Sodium Pentahydrate. Mol Pharm 2021; 18:2683-2693. [PMID: 34061524 DOI: 10.1021/acs.molpharmaceut.1c00217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A range of tablet excipients were evaluated for their influence on the physical form and chemical stability of levothyroxine sodium pentahydrate (LSP; C15H10I4NNaO4·5H2O). LSP-excipient binary powder blends were stored under two conditions: (a) in hermetically sealed containers at 40 °C and (b) at 40 °C/75% RH. By use of synchrotron X-ray diffractometry, the disappearance of LSP could be quantified and the appearance of crystalline levothyroxine (free acid) could be identified. Under hermetically sealed conditions (40 °C) hygroscopic excipients such as povidone induced partial dehydration of LSP to form levothyroxine sodium monohydrate. When stored at 40 °C/75% RH, acidic excipients induced measurable disproportionation of LSP resulting in the formation of levothyroxine (free acid). HPLC analyses of drug-excipient mixtures revealed that lactose monohydrate, microcrystalline cellulose, and croscarmellose sodium caused pronounced chemical decomposition of LSP. On the other hand, magnesium stearate, sodium stearyl fumarate, and alkaline pH modifiers did not affect the physical and chemical stability of the API following storage at 40 °C/75% RH. HPLC, being a solution based technique, revealed chemical decomposition of the API, but the technique was insensitive to physical transformations. Excipient properties such as hygroscopicity and microenvironmental acidity were identified to be critical determinants of both physical and chemical stability of LSP in a drug product. For drugs exhibiting both physical and chemical transformations, simultaneous solid-state and solution based analyses will enable comprehensive stability evaluation.
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Affiliation(s)
- Navpreet Kaur
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Raj Suryanarayanan
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455, United States
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