Ibuprofen crystals

Potential recovery. The objective is to maximize the potential recovery of ibuprofen crystals and this is posed as the objective function. The potential recovery for cooling crystallization is estimated using Eqn 12. 

Figure 8 Ibuprofen crystallized from 2-ethoxy ethyl acetate...

Fig. 11 (a) Optical microscopy images of the release from ibuprofen crystals covered with a (CHI/dextran sulfate)is shell 1 before dissolution 2 during dissolution and 3 after removal of the crystal cores. The mean size of the encapsulated ibuprofen microcrystals is 15.3 am. Reproduced from [112]. (b) Fluorescence increases with time, obtained by dissolving fluorescein crystals covered with shells of different thicknesses (9, 13, 15, and 18 polyelectrolyte-deposited PSS/PAH layers). The release from the native (uncovered) fluorescein crystals is shown as 0. Reproduced from [122]... 

The nature of solvent has been found to have a profound effect on crystal habit of ibuprofen. Ibuprofen crystals precipitated from ethanol and acetone (solvents having high surface tension, dielectric constant, and less specific gravity) were thin, platy, and nearly circular-shaped, whereas those obtained from propylene... 

Rasenack, N. Muller, B.W. Properties of ibuprofen crystallized under various conditions a comparative study. Drug Dev. Ind. Pharm. 2002, 28 (9), 1077-1089. 

Table 20. Adsorption parameters of cellulose derivatives on ibuprofen crystals and zeta potentials of the suspensions [117, [ 8]...

Ibuprofen crystals observed under SEM are in total disorder (Figure 15.2.3.8). This disordered arrangement of mieroerystallites inside the polycrystalUne partieles gives fliem a high isotropy of partieles arrangement that should improve their compression eapacity. 

FIGURE 5.5 Ibuprofen crystal habit predicted via (a) the BFDH model, (b) the attachment energy model, (c) and (d) as grown from hexane and ethanol, respectively. (From Win, D. and Doherty, M. F., AIChE J. 46 1348, 2000. With permission.)... 

How much of a crystallizable material X can I blend uniformly into a polymer until it starts to form crystals A series of blends with increasing amount of X is prepared. The samples are studied by WAXS (cf. Sect. 8.2) using laboratory equipment. Crystalline reflections of X are observed, as X starts to crystallize. Peak areas can be plotted vs. the known concentration in order to determine the saturation limit. Think of X being Ibuprofen and Y a polystyrene-(7 )-polyisoprene copolymer, and you have an anti-rheumatism plaster. 

Lot to lot variations of several drugs and excipients are shown in Table 9. Specially crystallized lots of ibuprofen, for example, show substantial changes in Brittle Fracture and Bonding Indices. Phenacetin shows a significant increase in brittleness at higher relative humidity. It was observed by Hiestand and Smith [31] that compacts of dried phenacetin did not fracture, while the lot equilibrated at 40% relative humidity did, consistent with the Brittle Fracture Index change. 

Fig. 13 Compaction profile of five specially crystallized lots of ibuprofen. See Table 12 for description.

Since the separated enantiomers of a dissymmetric compound must crystallize in a different space group than does the racemic mixture, it should not be unanticipated that quantitative XRPD would be useful in the determination of enantiomeric composition. For instance, the differing XRPD characteristics of (S)-(+)-ibuprofen relative to the (-RS)-racemate have been exploited to develop a sound method for the determination of the enantiomeric purity of ibuprofen samples [53]. 

A suitable amount of ibuprofen was dissolved in 5 ml of solvent at 40° C. Excess ibuprofen was added after saturation was reached at that temperature. Then the temperature was raised to 60° C. Precipitation was reached by cooling to 20° C over a period of 120 minutes, and then kept at that temperature overnight to allow maximum recovery of crystals. The obtained crystals were collected by filtration under vacuum condition and dried in a desiccator under vacuum. The solvents used were 2-ethoxy ethyl acetate (modeling result) and n-hexane. n-hexane was used for the purpose of comparison. 

Taking advantage of the ready availability of racemic ibuprofen, the resolution approach for production of (S)-(+)-ibuprofen becomes an attractive alternative. Merck s resolution process involves the formation of a diastereomeric salt of ibuprofen with (S)-lysine, an inexpensive and readily available natural amino acid.45 The racemic ibuprofen is mixed with 1.0 equivalent of (5)-lysine in aqueous ethanol. The slurry is agitated to allow full dissolution. The supernatant, which is a supersaturated solution of ibuprofen-lysine salt, is separated from the solid and seeded with (.S )-ibuprofcn-(.S )-lysine to induce crystallization. The precipitated solid is collected by filtration, and the mother liquor is recycled to the slurry of racemic ibuprofen and (S)-lysine. This process is continued until essentially all (S)-ibuprofen in the original slurry is recovered, resulting in the... 

To illustrate how a racemate system can be turned into a conglomerate system, and to demonstrate how one may recognize the existence of a conglomerate system, we will consider the example of ibuprofen, or 2-(4-isobutylphenyl)propanoic acid. The single crystal structures of enantio-merically pure [44] and racemic [45] ibuprofen have been published, and the powder diffraction patterns of the enantiomerically pure and racemic forms are shown in Fig. 9.3. The existence of a conglomerate system is indicated if the diffraction patterns of enantiomerically pure and racemic... 

It is important to note that unlike in precipitation method, both polar solvent, such as acetone, and nonpolar solvents, such as diethyl ether and hexane, produced needlelike crystals of ibuprofen when saturated solutions were cooled to 5°C over 120 min. Dichloromethane produced cubic, whereas acetonitrile produced spherical agglomerated crystals by this method. Solvent evaporation of ethanol gave platy... 

Fig. 4 SEM micrographs of ibuprofen commercial sample (A) crystals prepared by solvent change method using isopropyl alcohol (B) sodium hydroxide (C) acetonitrile (D). (From RefJ, p. 1083, by courtesy of Marcel Dekker, Inc.)...

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