Characterization of tenofovir, tenofovir disoproxil fumarate and emtricitabine in aqueous solutions containing sodium ions using ESI-MS, NMR and Ab initio calculations

Abstract

14We have discerned some characteristics of protonated and sodiated forms of emtricitabine 15 tenofovir and tenofovir disoproxil fumarate in aqueous solutions using mass spectrometry/mass 16 spectrometry (MS/MS), nuclear magnetic resonancespectroscopy (NMR) and Ab 17 initiocalculations. Protonated species exhibited different mass spectral characteristics from 18 sodiated species for the three antiretroviral drugs. Sodiation of the three compounds yields 19 extremely stable conformers which require high excitation energies to detach the sodium cation 20 using MS/MS. In the case of emtricitabine (FTC), collision induced dissociation (CID) of the 21 protonated species with m/z 248 yieldedm/z 130 as the major product ion by losing 2-ethyl-1,3-22 oxathiolane. MS/MS of the sodiated molecular ion [M+Na] + with m/z 270 would be expected to 23 yield [M+H] + i.e. m/z 248 by losing the Na + cation but instead lost 2-ethyl-1,3-oxathiolane and 24 left the Na + cation well sequestered within the ionic complex.Similar observations were made 25with tenofovir disoproxil fumarate (TDF) and tenofovir (TFV). Ab initio calculations showed in 26 the case of sodiated TDF and TFV that, the sodium could only be cleaved when a nucleophilic 27 species i.e. PO 2 to which it was coordinated to, fragmented requiring activation energy of 1.5 eV. 28 The potential energy barrier to remove the Na + cation alone was too high to allow the cleavage to 29 proceed. NMR data showed that when TFV or TDF coordinates with Na + ions at one of the 30 nitrogens at position 1 in the purine moiety of the molecule, it also interacts with oxygens of the 31 phospho group to form an ionic complex and perturbs the chemical environments of several 32 atoms in the periphery. The abundance of sodium cations and their strong interactions with the 33 core structures of FTC, TDF and TFV make sodiated species as the best candidates for their 34 quantitationusing MS/MSespecially in biological fluids. Evidence for improved sensitivity when 35 sodiated species of some of the antiretroviral (ARV) drugs were used for quantitation exists in 36 the literature. 37 2 1 1. Introduction 2Truvada® is a combination of emtricitabine (FTC) and tenofovirdisoproxil fumarate (TDF) 3 and is a nucleoside analog reverse transcriptase inhibitor (NRTI) used for treating HIV-1 in 4 adults and children of age 12 years and above. It contains two drugs and thus can be classified as 5 combination therapy. Dueto its widespread use, it is important to understand the behavior of the 6 individual components of the drug in vitro for purposes of following their fate in humans, the 7 environment in general and also for unravelling critical information necessary to develop 8 accurate and sensitive methods for their detection. Toxicologists in areas such as forensic and 9 analytical sciences may also derive interest in the behavior of thedrugs in humans and the 10 environment. Many analytical methods for the determination of the individual drug components 11 of Truvada® i.e. FTC and TDF have been de...

Tenofovir Disoproxil Fumarate Release From Glutaraldehyde Cross-Linked Chitosan/Β-Cyclodextrin Hydrogel

“…The NMR spectrum of the TDF showed strong and split peaks around 1.4 ppm, multiple multi-proton signals between 3.8 and 6 ppm, strong single proton signals at 7.2 ppm, and weak double and triple signals at 8.4 ppm. In the 1 H-NMR spectra of the TDF, Sichilongo et al [59] recorded doublet signals at 1 ppm, 1.2 ppm, 3.9 ppm, 4 ppm, and 4.2 ppm, multiple signals at 4.8 ppm, and singlet signals at 5.5 ppm, 6.6 ppm, 7.2 ppm, 8 ppm and 8.1 ppm.…”

Purification, characterization, and hypoglycemic properties of eurocristatine from Eurotium cristatum spores in Fuzhuan brick tea

“…The spray voltage of the electrospray ion source was set to 4 kV, the ion source temperature was set to 300 C, and nitrogen was used as the drying gas at a ow rate of 10 mL min À1 . 23,24 Nuclear magnetic resonance ( 1 H and 13 C NMR) spectra were obtained on a Swiss Bruker AVANCE AV 400 superconducting pulse Fourier transform nuclear magnetic resonance spectrometer. The chemical shis of the protons and carbons were recorded on the d scale of ppm.…”