IF you have ever found yourself worried about whether or not an elderly relative has taken his pill, researchers may have found the answer.

A team from Oxford University has been working on pills that send a text message to say they have been swallowed.

They hope the so-called texting pill could save the NHS millions of pounds.

The development comes after a study showed that £300m is spent each year on medicines that end up being thrown away.

The pill includes a tiny silicon sensor that emits a signal when it is swallowed which, via a patch on the body, sends a text message.

Prof Lionel Tarassenko, from the university’s institute of biomedical engineering, has been working with colleagues from the medical sciences division on the project.

He hopes to start a trial in Oxford next year using the texting pills with heart failure patients.

He told BBC Radio Oxford: “It’s a very simple idea and very difficult to make in practice. The idea is like a potato battery or a lemon battery, which sometimes you do as an experiment in school.

“If you stick two electrodes in a lemon or in a potato you get a battery, and effectively this is what is happening.

“On each pill you put a tiny, tiny silicon chip with two electrodes, and as it goes through your stomach the stomach is effectively acting like the potato or lemon battery and it activates a signal which is then picked up by a patch that you wear on your body telling you that the pill has actually reached the stomach.

“What happens next is the patch on your stomach picks up a signal and communicates via Bluetooth to a mobile phone or wi-fi in the home and texts the carer or a relative who may be concerned whether you have taken the pills.”

Prof Tarassenko said the pill, which is about the size of a grain of sand, was “harmless” and contained about a seventh of the amount of silicone in a banana.

He said: “Elderly people sometimes have to take six, seven or eight pills a day. If you have an elderly parent who is not taking their pills you might want to know.”

But Prof Tarassenko said it could be five to 10 years before the texting pills, which cost about 1p each to produce, would be regularly applied.

The technology is being developed by US firm Proteus Digital Health, in Silicon Valley, and UK pilots are being led by Lloyds Pharmacy and Oxford University.

The pharmacy company has completed a UK pilot with patients who have high blood pressure, who often need to take several medicines a day. The trials, like others in the US, have involved patients taking an extra dummy pill containing just the sensor, in addition to their medication.

Proteus hopes soon to embed the sensors in pills containing active drugs.

Proteus Digital Health chief executive officer Andrew Thomson said: “When you swallow one of our digital drugs it will say, ‘Hello I’m here, I’m Novartis, I’m Diovan, 1.2mg, I’m from plant number 76, I’m batch number 12 and I’m pill number two’.

“The invention could save the NHS hundreds of millions of pounds”.