BTG shares hit as medical product outlook disappoints

(Adds product details, latest shares)

LONDON, May 16 (Reuters) - British healthcare group BTG disappointed investors on Tuesday with a slower-than-expected forecast for growth in its interventional medicine business, sending the shares nearly 10 percent lower.

Despite reporting full-year sales that were slightly ahead of forecasts, helped by strong demand for DigiFab, an antidote for overdose of heart drug digoxin, prospects were weighed down by the cautious outlook for 2017/18, which analysts said put estimates at risk.

BTG - previously best known for drugs to treat overdoses and rattlesnake bites - has been reinventing itself in recent years by focusing on interventional medicine, in which image-guided devices are used to treat a range of diseases.

While established products in this division are selling well, growth has been slower for two newer products that are seen as pivotal for long-term success, Varithena for varicose veins and PneumRx for propping open diseased lungs.

For the current year, BTG (Frankfurt: 908827 - news) said interventional medicine would deliver mid-to-high teens percentage sales growth, at constant exchange rates (CER), well below the 26 percent that analysts at Jefferies said they had been forecasting.

Adjusted operating profit in the year to end-March was up 13 percent at CER at 129.6 million pounds ($168 million).

BTG shares, which have performed strongly this year on hopes for the company's shift to interventional medicine, were 9.5 lower at 653.5 pence by 1030 GMT. That is still up on the end-2016 level of 590p.

($1 = 0.7735 pounds)

(Reporting by Ben Hirschler; editing by Jason Neely and Susan Thomas)