cg9b01100_si_001.pdf (2.68 MB)
Engineering a New Access Route to Metastable Polymorphs with Electrical Confinement
journal contribution
posted on 2020-02-24, 20:12 authored by Aneesa
J. Al-Ani, Carmelo Herdes, Chick C. Wilson, Bernardo Castro-DominguezPolymorphism is the
ability of solid materials, including active
pharmaceutical ingredients (APIs), to exist in structurally distinctive
arrangements. The existence of polymorphism and the difference in
molecular packing can cause crystals to have a variety of different
physical properties. Therefore, the ability to experimentally control
and predict polymorph formation is vital to gain consistent access
to desired properties of APIs. In this study, polymorphic control
of the metastable form II of acetaminophen (paracetamol; PCM) was
achieved, coupling the use of electrospraying (a method that uses
electricity to atomize the precursor and create a charge on the surface
of small droplets) and a template component, metacetamol (MCM). Previously,
polymorphic control of APIs has been limited by the lack of ability
to switch between polymorphic forms with the change of a single variable
(such as voltage in electrospray experiments). Also, a single crystallization
method that is transferable between a wide range of APIs to gain polymorphic
control is not generally available. The electrospray technique as
a crystallization method offers a potentially powerful, mechanistically
distinct, and highly solvent-efficient alternative approach that promise
to overcome these limitations. This work shows that polymorph formation
is directly influenced by the thermodynamic conditions that induce
crystallization and that they can be affected by electrospraying,
guiding the crystal’s molecular arrangement via electric field
orientation and confinement. Electrospray has the potential for broad
applications in pharmaceutical crystallization and it can provide
an alternative starting point to transfer polymorphic systems into
continuous manufacturing platforms at an industrial scale.