US team develops hydrogel capsule for multi-drug delivery

11-Jul-2011 - Last updated on 12-Jul-2011 at 09:14 GMT

Researchers at the Georgia Institute of Technology have pioneered a multi-compartment gel capsule that could be used to simultaneously deliver drugs of different types.

The hollow hydrogel capsules - which measure less than one micron - have been fitted with polymer chains, providing separate compartments.

The team –L. Andrew Lyon, a professor in the School of Chemistry and Biochemistry at Georgia Tech, and former visiting scholar Xiaobo Hu – carried out the two-step, one-pot synthesis using core particles formed from temperature –sensitive polymer, poly (N- isopropylacrylamide).

The dissolvable core was then formed using polymer chains from the particles with a cross-linking agent, resulting in a collection of polymer chains with temperature-dependent stability.

In effect, if the next round of tests proves successful, the technology could be used to deliver distinct medication by filling the core of the capsule with hydrophilic drugs and trapping hydrophobic drugs within nanoparticles assembled from the polymer chains.

Lyon said: "The polymer comprising the core particles is known for undergoing chain transfer reactions that add cross-linking points without the presence of a cross-linking agent, so we initiated the polymerization using a redox method with ammonium persulfate and N,N,N’,N’-tetramethylethylenediamine.

“This ensured those side chain transfer reactions did not occur, which allowed us to create a truly dissolvable core.”

Hu and Lyon then added a cross-linking agent to a polymer called poly (N-isopropylmethacrylamide) to create a shell around the aggregated polymer chains.

Lyon said: "We have demonstrated that we can make a fairly complex multi-component delivery vehicle using a relatively straightforward and scalable synthesis.

“Additional research will need to be conducted to determine how they would best be loaded, delivered and triggered to release the drugs.”

The more the merrier

Simultaneous delivery of drugs has several potential advantages, including the ability to accurately control the relative dosage of various drugs, suppressed drug resistance, and synergistic effects.

This could be particularly beneficial in the field of oncology, where often combination chemotherapy has proven successful.

Lyon told In-PharmaTechnologist: "We have not determined the specific industry demand, but some potential clinical applications would be in co-administration of enzymes and an associated pro-drug, genes and drugs for enhanced transfection, and siRNA and drugs for combination chemotherapy to drug resistant tumors."

And though the team have yet to secure partners, Lyon nodded towards a potential relationship with companies who want a way to extend patent on a drug.

"This might be especially relevant when without such a carrier the scope of use of that drug is limited. The use of a novel carrier that permits a new mode of administration or efficacy in a different disease state could be used to extend a patent for a new scope of use."

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