Authors:Bogdan Tiţa, Adriana Fuliaş, Zoltan Szabadai, Gerlinde Rusu, Geza Bandur, and Dumitru Tiţa
It is well known that the majority of anti-inflammatory drugs are carboxylic acids.
Ibuprofen, α-methyl-4-(2-methylpropyl)benzeneacetic acid, which structural formula is shown in Fig. 1 , is a non
Authors:Mohamed A. Zayed, M. F. Hawash, M. A. Fahmey, and Ali M. M. El-Gizouli
Ibuprofen (IB, C 15 H 18 O 2 , MW = 206) drug, has an IUPAC name (R.S.-2-4-isobutylphenyl) propionic acid, as a derivative of 2-arylpropionic acid. It is a chiral non-steroidal anti-inflammatory drug [ 1 ]. It is
Ibuprofen has been subjected to a TG/DTA study over the temperature range of 30 to 350°C in a flowing atmosphere of nitrogen.
The heating rate and the flow rate were varied. The DTA shows a melting at around 80°C and boiling point range from 212 to
251°C depending upon the heating rate. The mass loss in the TG data confirms the evaporation of Ibuprofen between them.p. and the normalb.p. Evaporation is limited to the surface area, which is a constant in the crucible holding the sample. The DTG plot shows clearly
a zero order process which is consistent with the process of evaporation. The enthalpy of vaporization (ΔvapH) calculated by Trouton's rule is found to be in the range of 42.7–46.1 kJ mol−1. TheEact for the zero order reaction is in the range of 81.8–87.0 kJ mol−1 and is calculated by use of the derivative method. The value ofEact is about twice that for ΔHvap in Ibuprofen and differs from other compounds, whereEact≈Δ Hvap. It is suggested that the Ibuprofen molecule is existing as a dimer in the liquid state and dissociates to a monomer in the
Ibuprofen is one of the most common nonsteroidal anti-inflammatory and analgesic drugs. It is marked as a racemic mixture though it is known that the pharmacological activity resides in the (+)-(S)-enantiomer only. The process of conversion of (+)-(S)-ibuprofen enantiomer into (−)-(R)-enantiomer, inactive to cyclooxygenase, in methanol and cyclohexane using a chiral selector in TLC separation was investigated. Based on the values of k, t0.1, and t0.5, it is shown that the interconversion of (+)-(S) into (−)-(R)-enantiomer runs 10 times faster in polar methanol than in lipophilic cyclohexane.
The stability of Novozym® 435 in the esterification of ibuprofen using ethanol as reactant and solvent was investigated. Additionally, the surface
interaction of the isomers of ibuprofen and ethanol with the biocatalyst was screened through conventional adsorption isotherms
and temperature programmed surface reaction (TPSR). These investigations evidenced strong alcohol adsorption and dissolution
of the biocatalyst, which explains its deactivation upon reuses in the esterification reaction.
Authors:Mieczysław Sajewicz, Robert Piętka, and Teresa Kowalska
Chiral separations by gas and liquid chromatography (thin-layer chromatography included) remain an analytical challenge, hence even moderate success in this field is very likely to be regarded as a valuable separation achievement. There has been only one literature report of chiral separation of
-(−)-ibuprofen by TLC. The original procedure was performed with laboratory-coated glass plates and resolution of the two enantiomers in one-dimensional mode was incomplete. In an attempt to enhance the resolution the authors made use of less convenient and considerably more time-consuming two-dimensional TLC and the final result was not very impressive (Δ
= 0.03). These chromatograms were visualized by exposure of the developed plates to iodine vapor and no direct confirmation of the identity of the two chromatographic bands was produced.The goals of this study were: (i) to adapt the experimental conditions used for this separation to commercial chromatographic glass plates; (ii) to enhance the resolution of the two antipodes; and (iii) to produce up-to-date UV spectroscopic evidence of successful separation.
Authors:Nitin Dubey, Dinesh Jain, and Subhash Jadhawani
A stability-indicating high-performance thin-layer chromatographic (HPTLC) method has been developed for the determination of simultaneous determination of famotidine (FAMO), paracetamol (PCM), and ibuprofen (IBU) in tablet dosage forms. The separation was achieved on TLC aluminum plates precoated with silica gel 60F-254 using chloroform-methanol-ethyl acetate-acetic acid (21.5:16.1:59.1:3.2%, v/v/v/v) as the mobile phase. The densitometric analysis was carried out at 256 nm. Compact spots appeared at RF 0.21 ± 0.01, 0.80 ± 0.02, and 0.89 ± 0.01 for FAMO, PCM, and IBU, respectively. Linear regression analysis revealed linearity in the range of 160–960 ng per spot for FAMO, 400–2400 ng per spot for PCM, and 600–3600 ng per spot for IBU. Drugs were subjected to acid and alkali hydrolyses, forced oxidation, thermal and photodegradation treatments. The degraded products were well separated from the pure drugs. Statistical analysis proved that the method is precise, accurate, selective, and economical and may be used for routine analysis of FAMO, PCM, and IBU in tablet dosage forms.
Authors:Y. A. Ribeiro, J. D. S. de Oliveira, M. I. G. Leles, S. A. Juiz, and M. Ionashiro
Thermogravimetry, derivative thermogravimetry (TG, DTG) and differential scanning calorimetry (DSC), were used to study the thermal behaviour of mefenamic acid, ibuprofen, acetaminophen, sodium diclofenac, phenylbutazone, dipyrone and salicylamide. The results led to thermal stability data and also to the interpretation concerning the thermal decomposition.