COPIES of drugs are expected to have dented profits at GlaxoSmithKline (GSK).

The pharmaceuticals company will unveil its second-quarter results to the City today, which will reveal the extent of the damage caused by cheap rival products.

Like all medicine developers, GSK has a constant battle protecting the rights to its treatments.

But it has suffered a number of rulings on patents that have exposed it to the pressures of lower-cost generic competition.

Sales of its best-selling anti-depressants Wellbutrin and Paxil, as well as its antibiotic Augmentin, are expected to have been affected.

Analysts have predicted GSK will report that pre-tax profits have fallen to £1.54bn, a drop of more than 20 per cent.

The performance of GSK's best-selling asthma treatment, Advair, will also be of particular interest to investors.