The quest for the holy grail of insulin therapy – an oral formulation that will eliminate the need for injections – has taken a “significant step forward”, report researchers from the School of Pharmacy at Robert Gordon University in Aberdeen, Scotland.

At this week’s British Pharmaceutical Conference in Manchester, UK, Dr Colin Thompson and Dr Woei Ping Cheng are presenting evidence that novel amphiphilic graft polymers can successfully form nano-complexes with insulin, potentially guarding against gastrointestinal degradation and improving the insulin’s oral bioavailabilty.

The researchers synthesised the polymers by grafting polyallylamine with differing amounts of aliphatic moieties. The polymers were subsequently quaternised (i.e., converted into a compound with four elements) and their ability to form nano-complexes with insulin was investigated.

The resulting data suggested that non-quaternised and quaternised polymers behaved differently, the researchers noted. In the laboratory experiment, higher levels of complexation were achieved at lower non-quaternised polymer concentrations. However, complexation efficiency increased when higher concentrations of quaternised polymer were used, “possibly due to an increased level of positive charge of polymers forming compact nano-complexes with insulin”, Thompson and Cheng commented.

The researchers will now subject the polymers to further in vitro and in vivo testing to determine their suitability as insulin delivery systems – a goal that “is some years away”, according to Thompson, who added: “However, our research is taking us a significant step towards this important goal and offering hope to people who are living with diabetes.”

As Thompson pointed out, one of the key hurdles in developing an oral insulin formulation is that, swallowed without any kind of protection from enzymes in the gut, the insulin will be broken down before it has a chance to circulate in the blood and exert the desired effect on glucose levels.

Studies indicate that “a great many” people with diabetes fear injections, he said. Research also shows that some general practitioners delay initiating treatment for patients with type 2 diabetes because they wrongly assume the patient will be put off by a fear or dislike of injections.