Doctor Nose best

Forget painful injections, hard-to-swallow pills and nasty-tasting medicines, and get ready to start sniffing.

The nose is the up-and-coming route for delivering medication, and increasing numbers of drugs are being squirted, snorted and sprayed into the nasal passages for diseases as diverse as seasickness, diabetes, migraines and osteoporosis.

Some medication is already being delivered in this way, but around 120 clinical trials are under way worldwide where intranasal delivery of drugs is under investigation for more than two dozen conditions.

Nasal gels and fluids to prevent bacterial and vital infections as varied as MRSA, flu, Sars, and Ebola, as well as therapies for cancer symptoms, and new forms of vaccine, are also being tested.

Taking a drug orally has traditionally been the most common and the easiest way to take medication, but there are a number of drawbacks. A key disadvantage in many cases is that metabolism in the liver means only a proportion of the drug may get into the blood circulation.

As a result, larger doses have to be given in order to ensure the therapeutic amount gets to the right place, and that can increase the risk of side effects. Research on antihistamines and hay fever shows that while an oral dose can lead to drowsiness, no such side effect occurs when it is given intranasally because the required dose is much smaller. Stomach upsets associated with some oral drugs are also less likely.

A big advantage of nasal dosing is that it is a direct route into the circulation. Its inner surfaces, all 150 or so square centimetres of them, are rich in tiny veins which offer a direct and rapid way for drugs to get into the circulation.

And once in circulation they seem to become active much more quickly. Research on zolmitriptan nasal spray used for migraines shows that beneficial effects on symptoms were seen within 10 minutes far faster than with oral medication.

Acute pain is a key target for the new nasal drugs, largely because of the speed of action. Morphine is being used to combat cancer pain, while other drugs are tackling cluster headache, post-operative pain, and dental pain. A daily nasal spray has been shown to make bones stronger in patients with osteoporosis.

Nasal insulin is used for a number of conditions, including depression. At the University of Turku in Finland, children at risk of Type 1 diabetes are being given intranasal insulin, which doctors believe may delay or prevent development of the disease.

The nasal route is also being investigated as a way of preventing infections. A trial has begun in America where an experimental medication known as Poly-ICLC is being squirted into the noses of volunteers to investigate its potential for preventing or reducing the severity of infections from influenza and other viruses acquired through the nose, mouth and lungs. Animal studies have already shown that the drug is effective against mortality from influenza, Sars, smallpox and Ebola.

In one trial, a brain chemical involved in emotion is being used to treat symptoms of autism. A daily nasal spray based on the hormone oxytocin has been used by adults with autism in a trial at Mount Sinai School of Medicine in New York.

Oxytocin is produced in the areas of the brain that govern emotion and social skills. Autism is a developmental disorder with symptoms that include poor social functioning and repetitive behaviours; some research has suggested that low levels of oxytocin may be involved in the development of autism. Animal studies have found that oxytocin plays a role in a variety of behaviours, including social bonding, memory, anxiety reduction and repetitive behaviours.

In another trial, sponsored by the US National Institutes of Health, researchers are looking at the effects of an insulin nasal spray on memory and forgetfulness in patients with Alzheimer's disease. They say there is growing evidence to suggest that insulin plays a role in normal memory processes and that insulin abnormalities may contribute to brain changes associated with Alzheimer's.

Earlier studies have shown that nasal insulin can boost memory in both healthy older people and those with Alzheimer's. Both the healthy and the Alzheimer's patients performed significantly better on memory tests after getting insulin than getting a placebo. A study in Germany with healthy men found that after six weeks of treatment, they could recall more words from a list.

Nasal delivery may even be an unlikely route for boosting libido in women, with research showing that a nose spray based on testosterone, currently in development, increases libido and improves arousal in women over 40. Levels of the hormone decline with age and by the age of 40 a woman has about half her early adulthood levels. In brain-scanning research at Radboud University in the Netherlands, middle-aged women average age: 42 were given a nasal dose, which rapidly increased activity in an area of the brain associated with behaviour to a level comparable to that of a group of younger women whose average age was 23.

Women who had the nasal testosterone also had a greater emotional response when they were shown test pictures. The researchers say the effects were seen very quickly, within 45 minutes. And that kind of result is not to be sniffed at.

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