In controlled-release formulations, the excipients used are biodegradable polymeric compounds, such as PLGA or polyethylene
glycol, that are compatible with the Glide implant manufacturing process. By blending various grades of polymer, changing
the ratio of drug to polymer, and manipulating process conditions, varied release profiles can be created with Glide formulations.
On the other hand, if immediate release is required, the formulation would require quick-dissolving excipients, such as a
single sugar or a blend of sugars that provide the physical strength required, but dissolve within seconds in the tissue.
And although other excipients may be required to increase stability, such as for thermally labile biological macromolecules,
formulations remain relatively simple.
The manufacturing process for the solid dosage form is also simple: the active ingredient and a blend of selected excipients
are mixed together and passed through a standard twin-screw extruder, usually at room temperature to ensure that the active
ingredient is not damaged. The spaghetti-like extrudate is then cut into individual doses that are pointed at one end and
flat at the other. The drug implant is loaded into a sterile cassette and pushed directly into the tissue using a simple,
reusable spring-driven actuator. The rate of degradation of the polymeric matrix within the tissue controls the release of
the drug.
Potent drugs are good candidates for the company's solid-dose injection technology because they are administered in small
doses that can be delivered easily as small implants. Beyond dosage size, Glide's technology does not seem limited by drug
type. "We've got some very exciting vaccine data where we've shown the potential for better efficacy than a needle and syringe,
and we've worked with several peptides and proteins," says Potter.
Looking to the future, Potter sees a potential market in the treatment of Type II diabetes because of Glide SDI's suitability
to self-administered drugs. "Type II diabetics need a basal layer of insulin across the day. We can address Type II diabetes
with our system, but different people need different levels, so we would need several dose levels for our formulations."
Conclusion
Scientists are refining current technologies and developing new means of controlling the release of injectable drugs. Patients
seem likely to benefit from further innovations.
Reference
1. T.J. Merkel et al., Proc. Natl. Acad. Sci. USA
108 (2), 586–591 (2011).
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