Study on the structure and vibrational spectra of efavirenz conformers using DFT: Comparison to experimental data

Mishra, Soni; Tandon, Poonam; Ayala, A. P.

doi:10.1016/j.saa.2011.12.010

Cited by 16 publications

(10 citation statements)

References 39 publications

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“…These are the characteristic bands of n N-H and n C¼O , which are involved in the hydrogen bonding formation. Because these hydrogen bonding sites are driving forces for different crystal packing behaviors on recrystallization, the FTIR, XRPD, DSC, and TGA data support that EFZ/HEPT is a distinct polymorph, which was also described by Deshmukh et al 19 and Mishra et al 20 Using NMR, it was possible to identify self-aggregation and polymorphism in EFZ samples. In NMR solution, the single molecules and aggregate entities are clearly identified and distinguished through 1 H NMR spectra, using some NMR parameters, such as resonance number, shape, shifts, intensities and spinelattice relaxation rates, which are sensitive to changes in concentration, temperature, and solvent.…”

Section: Discussionsupporting

confidence: 64%

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Solution and Solid State Nuclear Magnetic Resonance Spectroscopic Characterization of Efavirenz

Sousa

Carvalho

Gil

et al. 2016

Journal of Pharmaceutical Sciences

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Section: Discussionsupporting

confidence: 64%

“…The n N-H band at 3317 cm À1 was sharp, although it is involved in the H-bond. 19,20 The medium band at 2249 cm À1 is assigned to n C≡C . The strong band at 1749 cm À1 is due to n C¼O , whereas the absorption band at 1317 cm À1 originated from n C-O .…”

Section: Fourier Transform Infraredmentioning

confidence: 99%

Solution and Solid State Nuclear Magnetic Resonance Spectroscopic Characterization of Efavirenz

Sousa

Carvalho

Gil

et al. 2016

Journal of Pharmaceutical Sciences

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“…The presence of drug in crystalline form with uniform distribution in SCS in the images of the hydrophilic regions in SCS described by the width at around 3027 to 3091 cm −1 green area was thought to be the carrier. (Mishra et al, 2012). Green fluorescence is due to polymer matrix and blue related to the drug particles.…”

Section: Raman Analysismentioning

confidence: 99%

Solid crystal suspension of Efavirenz using hot melt extrusion: Exploring the role of crystalline polyols in improving solubility and dissolution rate

Pawar

Fule

Maniruzzaman

et al. 2017

Materials Science and Engineering: C

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Poor aqueous solubility of drugs has emerged as a major issue for pharmaceutical scientists from many decades. The current study explores the manufacture and development of a thermodynamically stabilized solid crystal suspension (SCS) of poorly water soluble drug efavirenz via hot melt extrusion. Efavirenz is a non-nucleoside reverse transcriptase inhibitor and belongs to BCS class II. The SCS was prepared using pearlitol and xylitol as a crystalline carrier. The drug-excipient blend was processed by hot melt extrusion with up to 50% (w/w) drug loading. Physico-chemical characterization of the SCS conducted via a scanning electron microscopy, differential scanning calorimetry and hot stage microscopy confirmed that SCS are in crystalline state. Similarly, X-ray powder diffraction analysis revealed highly crystalline existence of pure drug, crystalline carriers and developed SCS. The FTIR chemical imaging analysis of SCS formulations showed a homogeneous drug distribution within respective crystalline carriers while an advanced chemical analysis via atomic force microscopy and Raman analysis complemented the foregoing findings. The developed SCS1 formulation showed up to 81 fold increase in the solubility and 4.1 fold increase in the dissolution rate of the drug compared to that of the bulk substance. Surprisingly, the developed SCS formulation remained stable for a period of more than one year at accelerated conditions inferred from dissolution studies. It can be concluded that the SCS approach can be used as an alternative contemporary technique to enhance the dissolution rates of many other poorly water-soluble drugs by means of thermal HME processing.

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“…The functional groups for EFV detected using Raman spectroscopy revealed that all expected signals observed for pure efavirenz and blank nanoemulsions were present and were in agreement with previously reported spectra [ 58 ]. The signal for the CH 2 (A) functional group at 3093 cm −1 , the C≡C (B) bond at 2250 cm −1 , the (C=O) (C) bond at 1750 cm −1 and the C–H stretch at approximately 1000 cm −1 reflect the presence of EFV [ 59 ]. A comparison of experimentally determined vibrational wavenumbers for EFV is listed in the Supplementary Materials (Table S8) .…”

Section: Resultsmentioning

confidence: 99%

Design, Optimization, Manufacture and Characterization of Efavirenz-Loaded Flaxseed Oil Nanoemulsions

2020

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The formation, manufacture and characterization of low energy water-in-oil (w/o) nanoemulsions prepared using cold pressed flaxseed oil containing efavirenz was investigated. Pseudo-ternary phase diagrams were constructed to identify the nanoemulsion region(s). Other potential lipid-based drug delivery phases containing flaxseed oil with 1:1 m/m surfactant mixture of Tween® 80, Span® 20 and different amounts of ethanol were tested to characterize the impact of surfactant mixture on emulsion formation. Flaxseed oil was used as the oil phase as efavirenz exhibited high solubility in the vehicle when compared to other vegetable oils tested. Optimization of surfactant mixtures was undertaken using design of experiments, specifically a D-optimal design with the flaxseed oil content set at 10% m/m. Two solutions from the desired optimization function were produced based on desirability and five nanoemulsion formulations were produced and characterized in terms of in vitro release of efavirenz, physical and chemical stability. Metastable nanoemulsions containing 10% m/m flaxseed oil were successfully manufactured and significant isotropic gel (semisolid) and o/w emulsions were observed during phase behavior studies. Droplet sizes ranged between 156 and 225 nm, zeta potential between −24 and −41 mV and all formulations were found to be monodisperse with polydispersity indices ≤ 0.487.

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Study on the structure and vibrational spectra of efavirenz conformers using DFT: Comparison to experimental data

Cited by 16 publications

References 39 publications

Solution and Solid State Nuclear Magnetic Resonance Spectroscopic Characterization of Efavirenz

Solution and Solid State Nuclear Magnetic Resonance Spectroscopic Characterization of Efavirenz

Solid crystal suspension of Efavirenz using hot melt extrusion: Exploring the role of crystalline polyols in improving solubility and dissolution rate

Design, Optimization, Manufacture and Characterization of Efavirenz-Loaded Flaxseed Oil Nanoemulsions

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