A new class of ''targeted'' drugs which tackle harmful effects of the menopause without the problems associated with hormone replacement patches could be on sale in Britain within a year.

Known as Serms - Selective oEstrogen Receptor Modulators - they work by targeting selected cells in the body while ignoring others, and were discussed during conference of gynaecologists and osteoporosis experts in Copenhagen, last week.

Hormone replacement therapy involves restoring the hormone oestrogen to the body, but carries the risk of side effects at best unpleasant, at worst dangerous.

Post-menopausal women on HRT often find they return to having monthly periods and suffer breast pain. It has also been claimed it can increase the chances of breast cancer.

But it offers major benefits in preventing osteoporosis - brittle bone disease - and reducing heart disease risks.

The new drugs are designed to stimulate receptors, points of molecular interaction on cells, in the same way as oestrogen. But while oestrogen is indiscriminate, Serms target specific receptors in specific places.

They stimulate receptors in the bone to stop oesteoporosis, and also target the cardio-vascular system to lower the level of fats in the bloodstream.

But, unlike oestrogen, they do not stimulate the uterus to resume bleeding, and they also ignore the cells of the breast.

The drugs were developed by American giant Lilly Industries, which has submitted licence applications in Europe and the US, and hopes to get the go-ahead to market them within a year.

Serms are not expected to replace HRT altogether, as they are not as effective at preventing some of the most common symptoms of the menopause, like flushes and hot sweats.