Ibuprofen description

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

Metastability and induction time can play an interesting role in the kinetic resolution of optical isomers, such as of resolution of ibuprofen lysinate (see Example 7.4). On the one hand in order to maintain the optical purity of the desired isomer, it is necessary to keep the (undesired) isomer in its supersaturated state for the entire crystallization period. If the undesired isomer crystallizes out from the solution, the optical purity of the desired isomer will decrease. On the other hand, it is important to release the supersaturation of the desired isomer, which starts at the same initial level of supersaturation as the undesirable isomer. These are two conflicting requirements. To overcome this dilemma, it is critical to maintain a large amount of seed bed of the desired isomer to accelerate the release of super-saturation of the desired isomer, whereas the undesired isomer remains supersaturated. As mentioned, a detailed description of the resolution process of optical isomers is given in Example 7-4. 

Naproxen toxicity can occur at very high doses (150-500 mg/kg). Naproxen toxicity is relatively uncommon compared to other NSAIDs such as aspirin and ibuprofen. See below for description of signs and symptoms of naproxen toxicity. 

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