3D printing - solid dosage forms Flashcards
what are the advantages and disadvantages of additive manufacturing
ad:
- can make complex structures at no additional cost
- can fit individual needs
- minimal waste
dis:
- slow
- lower quality products
- Quality insurance can be challenging due to customisation
how were some 3d printed tablets made to be fast-melting
gaps between granules = high surface area = water enters gaps and it melts quicker
how does powder based 3d printing work with a binder solution
spreading bar lays down a thin layer of powder containing all materials - evenly distributed
a printhead moves over the powder and sprays binder droplets onto selected areas
when binder touches the powder, it forms the desired shape.
what is in the binder solution in powder based 3d printing
solvent- helps carry the binder and surfactants ensuring it is spread evenly, surfactant - help liquid spread properly
why is a combination of water and ethanol used as the binder solution solvent rather than just water - powder based 3d printing
good wetting
it gives good spreading (thanks to water) but also faster drying (thanks to ethanol), making the printed layers cleaner and more precise.
the binder solution will evaporate after some time leaving the solid dosage form
how does powder based 3d printing work with a laser
thin layer of powder present on fabrication piston by a roller - even surface
high energy laser shone upon selected locations - causes partial melting of powders and consequently the fusion of them
what is a polypill
a pill containing different drugs
what is the benefit of a polypill
complex medicine regimes are contained in one personalised tablet. This can improve adherence
what is the compostion of the polypill
immediate release compartment (contains immediate release meds), extended release compartments (containing extended release meds), walls separating the compartments (made with cellulose, d-mannitol, plasticizer and DMSO)
how does inkjet printing work
the ink (medicine solution) is pushed out of a nozzle. The droplet size and spacing is determined by pressure. This is controlled by a piezoelectric actuator - changes volume under pulsed voltage = pressure wave
multiple drops can form a line
these are solidified using UV exposure that ensures links are made within the molecules in the ink
another layer can then be printed on-top
how is targetted delivery achieved using 3d printed drug delivery devices
the device is a 3d printed sphere containing the drug. The seal of the sphere is broken using infrared = this can be conducted at a specific time and location = targetted drug release.
what are the 4 steps to how drug delivery devices are 3d printed
Step i (two-photon microfabrication) — makes the basic hollow shell.
Step ii (magnetic decoration) — adds magnetism so they can be controlled later.
Step iii (centrifugal drug loading) — fills the hollow spheres with drug.
Step iv (automated sealing) — seals the drug inside with a smart, NIR-responsive layer.
(in more detail…)
Step i: Two-photon microfabrication
A laser beam writes tiny 3D structures (hollow spheres) inside a special resin by using two-photon absorption.
Basically, the laser hardens the resin only at precise points, creating a tiny 3D printed hollow shell.
Step ii: Magnetic decoration (Ni/Ti sputtering)
A thin layer of nickel/titanium is sprayed onto the surface using sputtering (a type of coating technique).
This gives the spheres magnetic properties, meaning they can later be steered with magnets.
Step iii: Centrifugation-based loading
The spheres are spun at high speed (centrifugal force) while being exposed to a drug solution.
The force pushes the drug solution inside the hollow spheres, filling them.
Step iv: Automated sealing
A sealing layer that responds to near-infrared (NIR) light is placed on top of the filled spheres.
This sealing layer locks in the drug — and later, NIR light can trigger it to open and release the drug when needed!
describe stereolithography
Laser shines onto liquid resin.
resin hardens where the laser touches
layer by layer drawno
how are micromirrors used in sterolithography
tilt to shine night in certain positions. where light hits, resin hardens
how does hot melt extrusion work for 3d printing solid dosage forms
-Mix poorly soluble drug and polymer together
-Mixture is melted and pushed through extruder- drug-polymer dispersion
-Extruded material- cut into pellets- 3D printed into specific dosage form
-Final product- drug is amorphous form inside polymer- better dissolution.
