title: Application of halloysite clay nanotubes as a pharmaceutical excipient.
abstract: Halloysite nanotubes, a biocompatible nanomaterial of 50-60nm diameter and ca. 15nm lumen, can be used for loading, storage and sustained release of drugs either in its pristine form or with additional polymer complexation for extended release time. This study reports the development composite tablets based on 50wt.% of the drug loaded halloysite mixed with 45wt.% of microcrystalline cellulose. Powder flow and compressibility properties of halloysite (angle of repose, Carr's index, Hausner ratio, Brittle Fracture Index, tensile strength) indicate that halloysite is an excellent tablet excipient. Halloysite tubes can also be filled with nifedipine with ca. 6wt.% loading efficiency and sustained release from the nanotubes. Tablets prepared with drug loaded halloysite allowed for almost zero order nifedipine release for up to 20h. Nifedipine trapped in the nanotubes also protect the drug against light and significantly increased the photostability of the drug. All of these demonstrate that halloysite has the potential to be an excellent pharmaceutical excipient that is also an inexpensive, natural and abundantly available material.
authors.affiliation: Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA 71272, USA.
authors.forename: Raghuvara
authors.initials: R
authors.lastname: Yendluri
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Otto
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, USA. Electronic address: melgardt.devilliers@wisc.edu.
authors.forename: Melgardt M
authors.initials: MM
authors.lastname: De Villiers
authors.affiliation: I. Gubkin Russian State University of Oil and Gas, Moscow 119991, Russia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Vinokurov
authors.affiliation: Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA 71272, USA; I. Gubkin Russian State University of Oil and Gas, Moscow 119991, Russia.
authors.forename: Yuri M
authors.initials: YM
authors.lastname: Lvov
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D000077215:Clay; D004355:Drug Stability; D005079:Excipients / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*; D009543:Nifedipine / Q000737:chemistry; D013607:Tablets
chemical_list: D000538:Aluminum Silicates; D005079:Excipients; D013607:Tablets; D009543:Nifedipine; D000077215:Clay
keywords: Excipients; Halloysite; Nifedipine; Sustained release; Tablets