How ‘dynamite patches’ blow away hot f lushes

PATCHES laced with the dynamite ingredient nitroglycerine are being used to treat menopausal hot flushes, offering a possible alternative to hormonereplacement therapy.

The compound, which is also found in medication for the heart condition angina, can reduce the frequency of hot-flush episodes in women by up to 70 per cent, according to new research.

Up to eight out of ten women in the UK experience symptoms leading up to the menopause, and almost half – 45 per cent – find symptoms difficult to deal with.

Hot flushes, one of the most common symptoms, involve a sudden feeling of heat in the upper body, which may start in the face, neck or chest, where the skin may become red and patchy, before spreading elsewhere.

It results in a rise in skin temperature in the face and upper body, which causes blood vessels just under the skin to get bigger. This leads to the reddening of the skin.

The exact cause is not known, but one theory is that the heat control centres in the brain send out faulty signals, possibly as a result of the changes in hormone levels, especially oestrogen, that occur around the time of the menopause.

In the new study, doctors used skin patches containing the nitroglycerin-type chemical glyceryl trinitrate (GTN) – found in angina patches called Ministran.

GTN works by being converted in the body to a chemical called nitric oxide, a substance made naturally by cells to relax and widen the veins and arteries, regulating blood flow.

By triggering the blood vessels to dilate, it becomes easier for the heart to pump blood around the body. Intriguingly, one side effect of the angina-type medication – taken only intermittently when symptoms such as chest pain occur – is facial flushing caused by the sudden rush of circulation.

However, continuous use leads to a tolerance which means that naturally occurring nitric oxide no longer works as well to widen blood vessels.

Although this tolerance limits the usefulness of GTN for chest pain, the researchers say that it offers a potentially innovative approach to treating hot flushes. Women who develop tolerance should experience a big reduction in hot flushes due to their own nitric oxide being less active.

The new study at the University of California involved women around the time of the menopause who had at least seven moderateto-severe hot flushes a day at the start of the four-week trial.

The women wore the daily patches continuously until the last week of the study. While high doses of GTN are associated with causing flushing, the trial volunteers were given a very low dose, which was gradually increased over four weeks.

Among the 17 women, the average daily frequency of hot flushes dropped by 54 per cent, and the average frequency of moderate-to-severe symptoms decreased by 69 per cent. After discontinuing nitroglycerin, there was an average 23 per cent increase in frequency.

‘Continuous nitroglycerin may substantially decrease hot-flush frequency and severity, and may offer a new nonhormonal hot-flush treatment,’ say researchers.

Other treatments include hormone-replacement therapy – tablets or patches that deliver synthetic oestrogen, progesterone or both – and clonidine, a medicine which was originally designed to treat high blood pressure but which has been found to reduce hot flushes and night sweats in some menopausal women.

Clonidine can cause unpleasant side effects, however, including drowsiness and depression.