Metal oxide encapsulated drug compositions and methods of preparing the same

A method of preparing a pharmaceutical composition comprising a drug- containing core enclosed by one or more metal oxide materials, the method comprising the sequential steps of:

• (a) loading particles comprising the drug into a reactor, wherein the particles have a median particle size, on a volume average basis between 0.1 μm and 1000 μm;
• (b) applying a vaporous or gaseous metal precursor to the particles in the reactor;
• (c) performing one or more pump-purge cycles of the reactor using an inert gas;
• (d) applying vaporous or gaseous water as an oxidant to the particles in the reactor;
• (e) performing one or more pump-purge cycles of the reactor using the inert gas;
• and
• (f) repeating steps (b)-(e) one or more times to increase the total thickness of the one or more metal oxide materials that enclose the core, wherein the particles remain in the reactor during the repeated steps, each pump-purge cycle comprises flowing the inert gas into the reactor chamber to a desired pressure and after a delay time pumping the inert gas out of the reactor until the pressure of the inert gas is below 1 torr and repeating the steps of flowing the inert gas into the reactor chamber to a desired pressure and after a delay time pumping the inert gas out of the reactor until the pressure of the inert gas is below 1 torr, the temperature of the particles does not exceed 35° C., thereby producing a pharmaceutical composition comprising a drug containing core enclosed by one or more metal oxide materials,
• wherein the one or more metal oxide materials are selected from the group consisting of:
• aluminum oxide, titanium oxide, iron oxide, gallium oxide, magnesium oxide, zinc oxide, niobium oxide, hafnium oxide, tantalum oxide, lanthanum oxide, and zirconium dioxide.