The objective of this work was to evaluate the biological properties of a new series of nitric oxide-releasing nonsteroidal anti-inflammatory drugs (NO-NSAIDs) possessing a tyrosol linker between the NSAID and the NO-releasing moiety (PROLI/NO); however, initial screening of ester intermediates without the PROLI/NO group showed the required (desirable) efficacy/safety ratio, which questioned the need for NO in the design. In this regard, NSAID ester intermediates were potent and selective COX-2 inhibitors in vitro, showed equipotent anti-inflammatory activity compared to the corresponding parent NSAID, but showed a markedly reduced gastric toxicity when administered orally. These results provide complementary evidence to challenge the currently accepted notion that hybrid NO-NSAIDs exert their cytoprotective effects by releasing NO. Results obtained in this work constitute a good body of evidence to initiate a debate about the future replacement of NSAID prodrugs for unprotected NSAIDs (possessing a free carboxylic acid group) currently in clinical use.

To study the behavior of the d- and l-isomers of ibuprofen in humans, a method for the determination of the individual enantiomers in plasma and urine was required. A specific procedure was developed based on (a) benzene extraction of the acidified specimens,(b) TLC of the benzene extract residue,(c) formation of the l-alpha-methylbenzylamides of the materials eluted from the chromatograms, and (d) quantification of the resulting diastereoisomeric amides by GLC in conjunction with flame-ionization detection. When using a 1-ml aliquot of the specimen, the method is sensitive to 1 mug of each enantiomer/ml of plasma or urine. As compared to simple aqueous solutions, the average recoveries of the enantiomers from plasma and urine ranged from 94 to96%. Mass spectrometric analyses, in conjunction with GLC, confirmed the specificity of the method for the intact enantiomers. The procedure was applied successfully to drug absorption studies in humans. After oral administration of the racemic mixture, the predominant enantiomer in peripheral circulation and excreted in urine was of the d-configuration.

A novel quasi-emulsion solvent diffusion method to prepare the controlled-release microspheres of ibuprofen with acrylic polymers has been developed. An ethanol solution of ibuprofen and acrylic resin was poured into aqueous medium with stirring. The finely dispersed ethanolic droplet-like coacervates formed in aqueous medium were gradually solidified and transformed into microspheres during agitation. The size of microspheres was determined by the concentrations of drug and polymer and the agitation speed of the system. The flowability, the packability, and the compressibility of the resultant microspheres were much improved compared with the raw crystals of the drug. The drug release rate from the microspheres could be controlled by the type and the concentration of polymer formulated. A unique principle of the present method and the resultant microspheres, having a matrix- or sponge-like texture, can provide characteristic advantages compared with a conventional reservoir-type device drug, like a microcapsule.

In this work we use both model dependent and independent techniques to assess the difference between dissolution profiles in which ibuprofen, in the form of uncoated pellets, is used as a model drug. The choice of a proper regression function, the relevance of the estimated parameters and the influence of the choice of dissolution points in the assessment of differences is discussed. The results obtained via mean dissolution times (MDT) and fit-factors (f(1) and f(2)) are also discussed and a non-quantitative method based on profiles correlation with graphical representation (concentration vs. concentration and rate vs. rate) presented. The tested methods discriminate similarly between curves, although not in all cases, but those based on modeling, MDT and fit-factors have shown to be less informative than the correlation approach.

A new series of nonsteroidal antiinflammatory drugs (NSAIDs) obtained by linking ibuprofen to selected furoxan moieties and to related furazans were synthesized and tested for their antiinflammatory, antiaggregatory, and ulcerogenic properties. All the derivatives are endowed with antiinflammatory activity comparable to that of ibuprofen, but, unlike this drug, they display reduced acute gastrotoxicity. The masking of the ibuprofen-free carboxylic group seems to be principally at the basis of this reduced topical irritant action. The two furoxan derivatives 8 and 9 also trigger potent antiaggregatory effects, principally as a consequence of their NO-donor ability.

Phospholipid micoremulsions have been suggested as a drug-delivery system for hydrophobic compounds. In this study hydrophobicity was achieved by derivatizing with cholesterol. Cholesteryl ibuprofen (3) and cholesteryl flufenamate (4) were synthesized. 3 was isolated as an amorphous, white solid with a melting range of 114-120 degrees C. 4 was isolated as a crystalline, white solid with a melting range of 145-148 degrees C. The proposed structures of 3 and 4 were supported by IR, NMR, MS, and organic microanalysis. Phospholipid:cholesteryl ester microemulsions were prepared by the addition of a 1-propanol solution of the cholesteryl ester, other lipids, and phospholipid to a rapidly mixing KCl/KBr solution. The hydrophobic phase was modified by the addition of cholesteryl oleate or triolein to study the effect of the fluidity of the hydrophobic core on the formation of the microemulsions. The results indicated that a molar ratio of 75:25 and a total lipid concentration of 60 mg/mL consistently gave microemulsions with a mean size of 100-150 nm. In addition, the formation of eutectic mixtures of 3 and 4 with cholesteryl oleate were determined to be 16%(w/w) for 3 and 12%(w/w) for 4; melting points were 35.2 and 45.2 degrees C, respectively. The solubilities of 3 and 4 in triolein were determined to be 13.2%(w/w) and 11.5%(w/w), respectively. Other investigators have shown that if the core of a phospholipid:cholesteryl estermicroemulsion exists in a liquid state at physiologic temperature, the turnover of the cholesteryl esters from these microemulsions occurs at a faster rate.(ABSTRACT TRUNCATED AT 250 WORDS)

The chromatographic resolution of the four stereoisomers of carboxy-ibuprofen, a major metabolite of ibuprofen in man, was achieved using a Chiralpak AD chiral stationary phase (CSP)(J.T. Baker, Milton, Keynes, UK). The elution order of the stereoisomers was determined to be 2'S,2R;2'R,2R;2'R,2S;2'S,2S by a combination of stereoselective synthesis of diastereoisomeric mixtures and analysis of the two diastereoisomers isolated from human urine following the administration of (S)-ibuprofen. The individual stereoisomers were isolated by semipreparative chiral phase chromatography and characterized by circular dichroism spectroscopy.

Fast dispersible tablets disintegrate either rapidly in water, to form a stabilized suspension, or disperse instantaneously in the mouth to be swallowed without the aid of water. A direct compression method was used to prepare these two types of tablets containing coated ibuprofen as a high dosed model drug. The properties of the water dispersible tablet, such as porosity, hardness, disintegration time and increase in viscosity after dispersion, were investigated. The selected tablet formulation, containing 26% galactomannan and 5% crospovidone, disintegrates before the galactomannan starts to swell. These tablets disperse in water within 40 s and show a crushing strength of 95 N. To develop an orodispersible tablet, a rotatable central composite design was applied to predict the effects of the quantitative factors mannitol and crospovidone as well as compression force on the characteristics of the tablet. Special emphasis was paid to the development of a wetting test, replacing the normal disintegration method. An optimum tablet formulation, containing 34% mannitol and 13% crospovidone, provides a short wetting time of 17 s and a sufficient crushing strength of 40 N. In conclusion, fast dispersible tablets with acceptable hardness and desirable taste could be prepared within the optimum region.

The synthesis of three oligomeric derivatives of 4-isobutylphenyl-2-propionic acid (ibuprofen), namely, the monoester of tetraethylene glycol (I) and the diesters of poly(oxyethylene) samples having molecular weights of 1000 (+/- 50) and 2000 (+/- 150)(II and III), has been performed via the imidazolide method. The antiinflammatory activity of I-III, and of equivalent amounts of free drug, was determined in the carrageenan-induced rat paw edema assay at different times after oral administration and found to be considerably prolonged in the case of the three derivatives. The lowest molecular weight derivative (I) also had an enhanced initial activity with regard to 4-isobutylphenyl-2-propionic acid. These results were confirmed by measuring the plasma levels of 4-isobutylphenyl-2-propionic acid in rats at different times after oral administration.

In order to reduce the ulcerogenic effect of ibuprofen, its carboxylic group has been converted into 5-membered heterocyclic rings. Various 1,3,4-oxadiazoles (3-8, 16-21), 1,2,4-triazoles (22-27), 1,3,4-thiadiazoles (28-30), and 1,2,4-triazine (9) derivatives of ibuprofen were prepared by cyclization of 2-(4-i-butylphenyl) propionic acid hydrazide (2) and N1-[2-(4-i-butylphenyl)-propionyl]-N4-alkyl/aryl-thiosemicarbazides (10-15) under various reaction conditions. The cyclized derivatives were screened for their anti-inflammatory activity by the carrageenan induced rat paw edema method and showed 50 to 86% inhibition, whereas the standard drug ibuprofen showed 92% inhibition at the same oral dose. Five compounds, 7, 16, 18, 22 and 30 that showed more than 80% anti-inflammatory activity were selected to study their analgesic, ulcerogenic and lipid peroxidation activities. All the tested compounds showed a significant reduction in ulcerogenic activity compared to ibuprofen through the severity index 0.5 to 0.8, vs. ibuprofen 1.8. The compounds, that showed less ulcerogenic effect also produced less malondialdehyde content in gastric mucosa, which is one of the end products of lipid peroxidation. The results of biological studies showed that oxadiazole derivative 16 as the lead molecule with maximum anti-inflammatory, analgesic and minimum ulcerogenic and lipid peroxidation activities.

An enantioselective esterification process was developed for the synthesis of 2-N-morpholinoethyl (S)-ibuprofen ester prodrug from racemic ibuprofen by using Candida rugosa lipase immobilized on Accurel MP1000 in cyclohexane. Compared with the performance of Lipase MY, the immobilized lipase possesses a higher enzyme activity and thermal stability, but with a slightly suppressed enantioselectivity. A kinetic model was proposed and confirmed from experiments, for the simulation of time-course conversions of both enantiomers at various combinations of substrate concentrations in a batch reactor. Preliminary results of employing the proposed model and the immobilized lipase in a continuous packed-bed reactor were also reported and discussed.