The pill that reminds you when it's time to take your next dose

A new era of "intelligent medicines" is heralded today with the disclosure that the NHS is about to begin trials of pills that contain a microchip, reminding patients when to take them.

When the pills are swallowed the "edible" microchips react with the acid in the stomach sending a message to a sticking plaster containing a sensor strapped to the shoulder. If the patient has forgotten a dose, the sensor delivers a text message to the patient's phone reminding them to take their pills.

In addition, the sticking-plaster sensor monitors the patient's bodily functions such as heart rate and can recommend adjustments to the dose accordingly, which can also be delivered to the patient via text message. The sensor can also send messages via the internet to carers and, if wanted, other family members, updating them on the patient's condition.

If successful, the system could improve patients' well-being while reducing costs by avoiding unnecessary hospital admissions.

The technology, developed by the US company Proteus in California, is being tested initially on 40 NHS patients with heart failure at Imperial College Healthcare Trust in London and the Royal Berkshire Trust in Reading. If successful, the four-month trial will be followed by a larger year-long trial starting in 2011 to measure the effect of the system on reducing hospital admissions.

Patients in the NHS trial will be given versions of two standard heart drugs – bisoprolol, a beta blocker that slows the heart beat, and furosemide, a diuretic that reduces fluid in the tissues – with the microchips incorporated in them.

The sticking-plaster sensor will measure heart rate, physical activity and whether the patients remain lying down while sleeping. If they are frequently forced to sit up, that is a sign of increasing fluid on the lungs, a common and potentially serious side effect of heart failure which requires urgent adjustment of the dose.

Research suggests that between a third and a half of patients do not take their medicines as instructed, leading to worse health, more hospital admissions and wasting $290bn (£186bn) a year in the US, according to a report by the New England Healthcare Institute published last year.

Unpleasant side effects, confusion over instructions, forgetfulness, language barriers and feeling "too well" to need medicine are among the reasons cited for non-compliance. People with chronic conditions such as diabetes and high blood pressure are least likely to stick to the regime prescribed by their doctor.

Nicholas Peters, professor of cardiology at Imperial College and a consultant to Proteus, said: "The whole idea of this technology is to inform patients about their own well-being, to encourage them to take the tablets and to take responsibility for their own health. It can help them stay stable and prevent them getting on to the slippery slope that leads to hospitalisation."

"People may say, 'Why do you need technology to detect a missed dose? If I feel ill I can adjust the dose.' But, in heart failure, once symptoms worsen it is often already too late. There is a narrow window. The patient can become fluid over-loaded and hospitalisation is the inevitable next step."

The microchip could be placed in almost any medicine. The technology has already been trialled in the US for psychiatric disorders where compliance is a particular problem.

Mobile-phone networks have already developed applications to remind patients to take their medicines, but the Proteus system, called Raisin, takes it a stage further. Networks could offer the application at a discount as an inducement to customers to join.

Dr Jerry Gurwitz, a geriatrician at the University of Massachusetts Medical School and expert on drug errors, said persuading patients to take the drugs they need is a challenging problem, especially among older people who live alone. "I think any person who is practising medicine is going to say it's one of the biggest challenges and frustrations of providing care to patients right now," he said.

The Proteus system has received the EU's consumer and health stamp of approval and the company is expected to seek regulatory approval for widespread use in the EU next year.