Controlled release of alendronate from nitrogen-doped mesoporous carbon

We have synthesized a nitrogen doped mesoporous carbon with the BET surface area of 1066 m(2)/g, total pore volume 0.6 cm(3)/g and nitrogen content of 0.5%. Total alendronate adsorption in this carbon was similar to 5%. The release experiments were designed in four different media with sequential pH values of 1.2, 4.5, 6.8 and 7.4 for 3, 1, 3 and 5 h, respectively and at 37 degrees C to imitate the physiological conditions of stomach, duodenum, small intestine and colon, respectively. Release of the drug demonstrated a controlled fashion; only 20% of the drug was released in the media with pH = 1.2, whereas 64% of the drug was released in pH = 7.4. This is in contrary to pure alendronate that was completely dissolved within 30 min in the first release media (pH = 1.2) only. The relatively larger uptake of alendronate in this carbon and its sustained fashion of release can be attributed to the hydrogen bonding between the drug and the nitrogen functionalities on carbon surface. Based on this result, it can be inferred that this formulation may lower the side effects of oral delivery of alendronate. (C) 2016 Elsevier Inc. All rights reserved.