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44 September 2015 Tablets & Capsules eye on Use with four APIs Preisig and et alia studied the feasi- bility of using a particular grade of FCC (PSD average of 17.9 microns and SSA of 35.43 m 2 /g) as a carrier for four poorly water-soluble APIs [2]. The authors studied FCC's loading capacity, the percentage of amorphous drug it could carry, and the dissolution performance when it was combined with ibuprofen (IBU), nifedipine (NF), losartan potassium (LP) and metron- idazole benzoate (MB). The four APIs were dissolved in methanol or acetone and mixed with FCC, and the solvents were then removed using a rotary evaporator that controlled the pressure. Next, the FCC-API particles were loaded with 25 to 50 percent (w/w) of each API in increments of 5 percent (w/w). For ref- erence, the authors also created FCC- API mixtures that contained equivalent API fractions but were not subject to a specific loading strategy, and loading efficiency was assessed using a scan- ning electron microscope (SEM). The presence of particle agglomerates or drug crystals outside the FCC particles indicated the maximum loading capac- ity. The authors reported that the par- ticles could accommodate as much as 40 percent (w/w) of API. They also observed a reduction in the interparti- cle porosity of bulk FCC (63 percent for MB, 58 percent for IBU, 50 percent for NP, and 35 percent for LP), which provided evidence of pore filling. API loading was also quantified by HPLC- UV. Furthermore, the dissolution rate of the NF and MB was faster for the API- loaded FCC than it was for API-FCC mixtures. Since only low percentages of amorphous NF (8.9 percent) and MB (12.5 percent) were found using differential scanning calorimetry, the authors concluded that the faster dis- solution was related to the local increased solubility due to the larger surface area and not to the presence of an amorphous API. Also, the authors concluded that FCC particles could be loaded with APIs and thus used as a drug carrier. In addition, it's possible that the FCC could accelerate the release of certain poorly soluble APIs. Carolina Diaz Quijano Omya International excipients This edition of the column describes func- tionalized calcium carbonate, a structured mineral that serves as a multifunctional excipient. It summarizes three studies of the substance that demonstrate applications in formulation of tablets, orally disintegrating tablets, and orally disintegrating granules. New active pharmaceutical ingredi- ents (APIs) are increasingly challeng- ing to formulate using excipients that comply with the regulatory require- ments. It can also be difficult to find multifunctional excipients that do not multiply an already extensive regula- tory burden. But functionalized cal- cium carbonate (FCC) is different. It's a structured mineral comprising cal- cium carbonate and hydroxyapatite, both of which are monographed min- erals [1]. Properties FCC is manufactured from calcium carbonate, which undergoes a process of surface re-crystallization to create a structured mineral with multiple func- tionalities (Figure 1). The excipient's external lamellar structure encloses a core of interconnected pores, giving the particles several desirable proper- ties, including the ability to be used in dry granulations and to accommodate high API loading. Moreover, the sur- face re-crystallization process can be controlled to obtain the desired spe- cific surface area (SSA) over a range of 40 to 120 square meters per gram (m 2 /g); a particle size distribution (PSD) with a mean diameter of 2.5 to 30 microns; and pore sizes of 60 to 80 percent (v/v). Figure 1 Micrographs of natural calcium carbonate and FCC b. FCC, a highly porous structured mineral, is obtained through surface re-crystallization of natural calcium carbonate. a. Natural calcium carbonate