Fabrication and Lyophilization of Micro-Tablets
Sometimes drugs need to be delivered in very small quantities via implants. A company I work for, On Demand (a spin out of MicroChips Biotech and MIT), has just received the patent on an amazing new micro-tablet technology. As Head of Development on this project, I helped devise a method for lyophilizing medicines into cylinders that were made into micro-tablets for implantable, slow-release drug delivery.
These tiny tablets are only 1/2 mm in diameter. They’re useful for micro-implant eye devices that have control-release drugs. The method used to fill these micro-tablets is extremely efficient and allows us to fill them to a precise quantity.
Lyophilization and Hermetic Seal
These medicines cannot be in liquid form because they degrade easily. So we needed to lyophilize the drugs to take all the water out. The lyophilization process is done in a lab in California. The medicine then needs to be transported safely to Boston. So, our team designed a method for hermetically sealing the capsule for safe travel.
We built a unique holder that allowed for good thermal and vapor transfer. With precise tube lengths, we used capillary action to wicks an exact volume of the liquid medicine into the tube via capillary action. A custom chamber then evenly cools the drug cylinder for controlled lyophilization. All the air is removed from the freezer, creating a vacuum. The ice sublimes, leaving only a powder cake of the drug. The carrier is then hermetically sealed and transported to our clean room in Boston where the drugs are compressed into tablets.
Compression into Micro-Tablets
To tabletize the drug, a very small piston compresses down the capillary bore. The drug is compressed into a 1/2 mm by 1 mm tablet. Once formed, the product can be dispensed to other capsules or carriers. These drugs can be used in micro-implants to deliver very small quantities of drugs for controlled release. This method is for an implantable eye device, and there may be many other applications of these micro-tablets in the future.