Scientists have developed a new technology that may allow orally administered drugs to bypass the liver and get absorbed directly and quickly into the blood stream.
For years, scientists and dietitians have argued over the health benefits of dietary fat. Researchers have now shown that piggybacking onto natural fat absorption pathways can dramatically enhance the utility of some drugs.
One of the key goals of drug development has been to produce a therapy that can be taken orally (therefore cheap and easy to deliver) and is absorbed as directly and quickly into the blood stream as possible, according to researchers from ARC Centre of Excellence in Convergent Bio-Nano Science (CBNS) in Australia.
Many medications, however, 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.
Researchers have now developed a new technology that allows orally administered drugs to by-pass the liver.
This technology makes use of a natural nano-scale lipid transport system that delivers drug from the gut through the lymphatic system, and straight into the blood stream.
According to Professor Chris Porter from CBNS, the technology has 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.
He said that 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.
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 bloodstream) and to avoid this first pass metabolism in order to get to the general circulation where it acts," said Porter.
Researchers have been fine tuning what is called a pro-drug technology. Aimed specifically at targeting drug absorption to the lymphatic system (rather than the hepatic portal blood) 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 lymphatics drain directly into the blood and do not pass through the liver. This can dramatically enhance the efficiency of drugs with first pass metabolism problems like testosterone," said Porter.
"Drug delivery directly into the lymph may enhance the utility of drugs that are designed to stimulate the immune system to eg fight cancer, or to suppress the immune system to fight autoimmune diseases such as Crohn's Disease," he said.
The findings were published in the journal Angewandte Chemie.
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