Regular pill-taking is soon to become a thing of the past according to scientists in an EU consortium who have developed a new prosthesis that releases the correct dosage of the required medicine on a continuous basis. It is designed to help to avoid the peak concentrations that occur on taking pills, aggravating side effects.

The Intellidrug prosthesis is small enough to fit into two artificial molars, unlike existing drug prostheses and implants. Inside the patient's mouth, it is readily accessible and can easily be maintained and refilled.

The dental prosthesis consists of a drug-filled reservoir, a valve, two sensors and several electronic components, explains Dr Oliver Scholz of the Fraunhofer Institute for Biomedical Engineering (IBMT) in St Ingbert, Germany, where the sensors and electronics were developed.

Saliva enters the reservoir via a membrane, dissolves part of the solid drug and flows through a small duct into the mouth cavity, where it is absorbed by the mucous membranes in the patient's cheeks.

The duct is fitted with two sensors that monitor the amount of medicine being released into the body. One is a flow sensor that measures the volume of liquid entering the mouth via the duct, while the other measures the concentration of the agent contained in the liquid. Based on the measurement results, the electronic circuit either opens or closes a valve at the end of the duct to control the dosage. If the agent has been used up, the electronic system alerts the patient via a remote control, which was also developed at the IBMT. This control permits wireless operation of Intellidrug, and can be used by the patient or doctor to set the dosage required.

The patient has to have the agent refilled every few weeks. This could be done using a deposit system whereby the patient swaps the empty prosthesis for a newly refilled one. At the same time, the battery could be replaced and the device could be serviced, says Dr Scholz. Intellidrug is to undergo clinical testing this year – filled with a drug called Naltrexon, which is taken by drug addicts undergoing withdrawal therapy.