A drug delivery technology developed by Emisphere Technologies has been shown to provide effective oral administration of protein-based drugs in three studies presented at the Controlled Release Society's annual meeting in Glasgow, Scotland.
The system, called eligen , is based on the use of proprietary, synthetic chemical compounds that facilitate the transport of the large therapeutic molecules across biological membranes such as the small intestine without altering its chemical form or biological integrity.
The first study explored the mechanism behind the eligen technology and, using insulin as a model, demonstrated that the lipophilicity (solubility in lipids) of the protein was increased. The more lipophilic a molecule is, the more amenable it is to crossing a cell membrane. Importantly, the study showed that insulin delivered using this system was taken up by well-recognised transcellular pathways and did not damage the epithelial cells lining the intestine.
In a second study, Emisphere was able to demonstrate that oral dosing of an oral insulin prototype was able to have an effect on glucose levels in type 2 diabetes patients. This measured glucose clamping, a method to assess insulin secretion and resistance based on measuring the rate of glucose infusion required to maintain constant glucose levels after insulin administration.
The open-label study compared the pharmacokinetic and pharmacodynamic profiles of Emisphere's insulin (2 capsules containing 300 International Units) with a subcutaneous 15 IU dose of the hormone.
"The data demonstrated an appropriate reduction in blood sugar following the oral insulin administration of each of the two treatments, as well as a tight range of time to maximum insulin concentrations," said Emisphere. The relative potency of the oral insulin compared to the injection was 20 per cent in the first hour after administration, the time period of greatest importance, it added.
A third study looked at liquid and capsule formulations of recombinant human growth hormone in primates, a project partnered with Eli Lilly, which markets the Humatrope (somatropin) brand of rhGH.
This study found that the capsule formulation achieved acceptable blood levels of rhGH within 30-60 minutes of administration, opening the way for a first clinical trial of the approach in humans. To date, rhGH is the largest protein to be orally delivered in humans using the eligen technology.