Controlled release of alendronate from nitrogen-doped mesoporous carbon

• Nitrogen-doped carbon was synthesized with BET surface area 1066 m2/g.
• Alendronate was release in pH = 1.2, 4.5, 6.8 and 7.4 at 37 °C.
• Only 20% of alendronate from carbon was released in pH = 1.2.
• All alendronate was released in pH = 1.2 in 30 min only.

We have synthesized a nitrogen doped mesoporous carbon with the BET surface area of 1066 m2/g, total pore volume 0.6 cm3/g and nitrogen content of 0.5%. Total alendronate adsorption in this carbon was ∼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 °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.

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