Researchers have developed a new technology that makes use of a natural fat absorption system to deliver drugs from the gut straight into the blood stream by by-passing the liver.

Many medications are broken down in the liver before even making it into the blood stream.

This is called "first past metabolism" whereby the drugs we swallow go via the gut and the liver (where breakdown occurs) before even entering the blood.

Scientists have long tried to bypass this process since it can prevent enough drug getting to the site of action to be useful.

The new technology makes use of a natural nano-scale lipid transport system that delivers drugs from the gut through the lymphatic system, and straight into the blood stream.

Tested on testosterone in animal models, the technology has the potential to be used for a range of drugs that struggle to get through the liver and into the circulation, as well as for drugs targeted to the lymphatic system, said Chris Porter from ARC Centre of Excellence in Convergent Bio-Nano Science (CBNS) in Melbourne, Australia.

The liver is a marvellous organ for filtering and protecting the body from materials it regards as foreign and breaking them down before they can be toxic, Porter said.

While this is a great advantage when protecting the body from dangerous toxins, it can severely limit the amount of a drug that reaches the site of action after oral administration.

"No matter how good the drug is, it needs to be absorbed (into the blood stream) and to avoid this first pass metabolism in order to get to the general circulation where it acts," he said.

Aimed specifically at targeting drug absorption to the lymphatic system this technology modifies drugs so that they chemically mimic dietary lipids.

Unlike most nutrients, after absorption lipids are assembled into nano-sized lipid droplets or lipoproteins and transported to the circulation via the lymph.

The findings were reported in the journal Angewandte Chemie International Edition.