3-Methylglutaric acid as a 13C solid-state NMR standard

Barich, Dewey H.; Gorman, Eric M.; Zell, Mark T.; Munson, Eric J.

doi:10.1016/j.ssnmr.2006.06.001

Cited by 61 publications

(57 citation statements)

References 11 publications

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“…Each sample was packed under ambient conditions in a 7-mm zirconia rotor (Revolution NMR, Fort Collins, Colorado). 3-Methylglutaric acid was used as an external standard, with methyl peak referenced to 18.84 ppm (11). All spectra were acquired using ramp cross polarization and magic angle spinning (CP/ MAS) (12)(13)(14).…”

Section: Ssnmr Spectroscopymentioning

confidence: 99%

Investigating Gabapentin Polymorphism Using Solid-State NMR Spectroscopy

et al. 2012

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Abstract. Solid-state NMR spectroscopy (SSNMR), coupled with powder X-ray diffraction (PXRD), was used to identify the physical forms of gabapentin in samples prepared by recrystallization, spray drying, dehydration, and milling. Four different crystalline forms of gabapentin were observed: form I, a monohydrate, form II, the most stable at ambient conditions, form III, produced by either recrystallization or milling, and an isomorphous desolvate produced from desolvating the monohydrate. As-received gabapentin (form II) was ball-milled for 45 min in both the presence and absence of hydroxypropylcellulose (HPC). The samples were then stored for 2 days at 50°C under 0% relative humidity and analyzed by 13 C SSNMR and PXRD. High-performance liquid chromatography was run on the samples to determine the amount of degradation product formed before and after storage. The 1 H T 1 values measured for the sample varied from 130 s for the as-received unstressed material without HPC to 11 s for the material that had been ball-milled in the presence of HPC. Samples with longer 1 H T 1 values were substantially more stable than samples that had shorter T 1 values. Samples milled with HPC had detectable form III crystals as well. These results suggest that SSNMR can be used to predict gabapentin stability in formulated products.

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Section: Ssnmr Spectroscopymentioning

confidence: 99%

Investigating Gabapentin Polymorphism Using Solid-State NMR Spectroscopy

et al. 2012

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“…The free induction decays consisted of 1,024 data points with a dwell time of 33.3 μs. The spectra were externally referenced to tetramethylsilane using the methyl peak of 3-methylglutaric acid at 18.84 ppm [27].…”

Section: Solid-state Nmr Spectroscopymentioning

confidence: 99%

NanoCipro encapsulation in monodisperse large porous PLGA microparticles

Arnold

Gorman

Schieber

et al. 2007

Journal of Controlled Release

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Pulmonary drug delivery of controlled release formulations may provide an effective adjunct approach to orally delivered antibiotics for clearing persistent lung infections. Dry powder formulations for this indication should possess characteristics including; effective deposition to infected lung compartments, persistence at the infection site, and steady release of antibiotic. Large porous particles (∼10-15 μm) have demonstrated effective lung deposition and enhanced lung residence as a result of their large diameter and reduced clearance by macrophages in comparison to small microparticles (∼1-5 μm). In this report, Precision Particle Fabrication technology was used to create monodisperse large porous particles of poly(D,L-lactic-co-glycolic acid) (PLGA) utilizing oils as extractable porogens. After extraction, the resulting large porous PLGA particles exhibited a low density and a web-like or hollow interior depending on porogen concentration and type, respectively. Ciprofloxacin nanoparticles (nanoCipro) created by homogenization in dichloromethane, possessed a polymorph with a decreased melting temperature. Encapsulating nanoCipro in large porous PLGA particles resulted in a steady release of ciprofloxacin that was extended for larger particle diameters and for the solid particle morphology in comparison to large porous particles. The encapsulation efficiency of nanoCipro was quite low and factors impacting the entrapment of nanoparticles during particle formation were elucidated. A dry powder formulation with the potential to control particle deposition and sustain release to the lung was developed and insight to improve nanoparticle encapsulation is discussed.

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“…All solid-state experiments included ramped-amplitude cross polarization (28,29) and magic angle spinning (30) at a rate of 5 kHz, and SPINAL64 decoupling (31) at a field strength of ∼72 kHz. Spectral acquisitions included total suppression of spinning sidebands (32), and samples were externally referenced with 3-methylglutaric acid (33) Pulse delays of at least 1.5 times the 1 H T 1 (obtained via inversion recovery) were used 400, 65, and 45 s for LMT, CYA, and their salt, respectively. All spectral acquisitions took place at ambient temperature.…”

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Improvement of Physicochemical Properties of an Antiepileptic Drug by Salt Engineering

et al. 2012

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Abstract. The focus of the present investigation was to evaluate the feasibility of using cyclamic salt of lamotrigine in order to improve its solubility and intrinsic dissolution rate (IDR). The salt was prepared by solution crystallization method and characterized chemically by fourier transform infrared spectroscopy (FTIR), proton ( 1 H) and carbon ( 13 C) nuclear magnetic resonance (liquid and solid, NMR) spectroscopy, physically by powder X-ray diffraction (PXRD), thermally by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), physicochemically for solubility, IDR, solution and solid-state stability, and polymorphism by solution recrystallization and slurry conversion studies. The FTIR, NMR, PXRD, DSC, and TGA spectra and thermograms indicated the salt formation. The salt formation increased lamotrigine solubility by 19-fold and IDR by 4.9-fold in water. The solution and solid-state stability were similar to parent molecule and were resistant to polymorphic transformation. In conclusion, cyclamic salt of lamotrigine provides another potential avenue for the pharmaceutical development of lamotrigine with improved physicochemical properties especially for pediatric population. It is also possible that appropriate dosage forms can be formulated with much lower drug amount and better safety profile than existing products.

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3-Methylglutaric acid as a 13C solid-state NMR standard

Cited by 61 publications

References 11 publications

Investigating Gabapentin Polymorphism Using Solid-State NMR Spectroscopy

Investigating Gabapentin Polymorphism Using Solid-State NMR Spectroscopy

NanoCipro encapsulation in monodisperse large porous PLGA microparticles

Improvement of Physicochemical Properties of an Antiepileptic Drug by Salt Engineering

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