Controlled-release product extraction

Sonication using ultrasonic cleaner baths remains a popular extraction approach particularly for controlled-release products. In sonication, an ultrasonic wave of 20-40 kHz generated by a piezoelectric transducer is used to produce the formation and collapse of thousands of microscopic bubbles (cavitations) in the water bath to facilitate the break up of the solid particles and the subsequent dissolution of the API. Note that parameters such as the wattage power of the sonicator, presence of the perforated tray, depth of the water level, bath temperature and the number of sample flasks sonicated might all affect the extraction rate. For... 

This case study illustrates the SP method development of an assay method for a controlled-release analgesic tablet with a single API. Certain considerations were taken into account. First, the analyte within the tablet matrice core had to be extracted quantitatively. Second, the analyte was diluted into a final solution that was compatible with the HPLC mobile phase. Third, short SP time was required (i.e., 30 min) to maximize productivity of the work scheme for processing a large number of samples. 

Natural products can be used as plant extracts with pharmacological activity (e.g., Mangifera indica L., vallerian, aloe, Cratoxylum pruniflorum, microporous zeolite), excipient for direct compression or granulation (chitin, chitosan, and dextran), and controlled-release systems (cellulose and native dextran). For natural products the most important factor is the standardization of the extract because properties such as the amount of active substance can be changed from batch to batch. Factors such as the origin of the extract, geographic zone, and age of the tree could affect the properties of natural extracts. 

Controlling mercury releases through end-ofpipe techniques, such as exhaust gas filtering, may be especially appropriate to processes using raw materials with trace mercury contamination - fossil-fueled power plants, cement production, extraction and processing of primary raw materials such as zinc, gold and other metals, and processing of secondary raw materials... 

Sah H. Microencapsulation techniques using ethyl acetate as a dispersed solvent Effect of its extraction rate on the characteristics of PLGA microspheres. Journal of Controlled Release. 1997 47 233-245. Nagai A, Ohtani S, Takechi N. Production of microspheres. EU patent 1142567, 2002. 

Yeh MK, Coombes AG, Jenkins PG, Davis SS. A novel emulsification-solvent extraction technique for production of protein loaded biodegradable microparticles for vaccine and drug delivery. Journal of Controlled Release. 1995 33 437-445. 

Citric acid esters are discussed in the review papers, patents, and conunercial litera-ture. ° " " Citric acid based plasticizers are one of the major contenders to replace phtha-lates (especially targeted to replace DOP). ° Some properties of materials plasticized with citrates can match those of DOP plasticized PVC but the cost of their production is substantially higher. Citrates are extracted from flexible PVC at a higher rate than DOP and trimellitates." Eudragit, which is a choice polymer in pharmaceutical coatings, having controlled release or sustained release properties, performs its functions very well when plasticized with triethyl citrate.The concentration of plasticizer can be used as the parameter that regulates the release rate. 

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