* FTSE 100 index drops 0.3 pct in early trading
* GlaxoSmithKline leads drugmakers lower
* Vodafone down on weaker organic service revenue
By Atul Prakash
LONDON, Nov 12 (Reuters) - Britain's top share index dipped in early trading on Tuesday, with GlaxoSmithKline leading pharmaceutical companies lower after one of its experimental heart drugs failed to meet targets in a first study.
The market was also pressured by weaker mining stocks as metals prices fell on caution ahead of an announcement from top consumer China on reforms for the next decade. The UK mining index dropped 0.7 percent, while Anglo American fell 1.8 percent.
The FTSE 100 was down 22.98 points, or 0.3 percent, at 6,705.39 points by 0843 GMT, while GlaxoSmithKline dropped 1.2 percent after an experimental drug, designed to fight heart disease in a new way, failed to meet its main goal in the first of two big late-stage clinical studies.
The FTSE 100 has slipped from a five-month high scaled in late October. Analysts, however, said the blue-chip index was not pointing towards the start of a downward trend and they remained positive on the outlook for the market, which is still up about 14 percent this year.
"The key fundamental drivers are still looking supportive for equities," Robert Parkes, equity strategist at HSBC Securities, said.
"The growth outlook is improving, monetary policy is still accommodative and there is potential for earnings to surprise on the upside as we head into 2014."
An improving housing market is also a sign of rising optimism. A survey on Tuesday showed that government incentives to support the housing market boosted the number of people wanting to buy homes last month and helped to push prices to an 11-year high.
"The UK index is still within striking distance of its recent high and there is little in the current technical picture to suggest that it is about to fall away," Bill McNamara, technical analyst at Charles Stanley, said in a note.
"Last week's trading low, at 6,643, is probably the level to watch in terms of support."
Among individual movers, Vodafone fell 0.4 percent after the world's second-largest mobile operator posted a record fall in quarterly organic service revenue and said it planned to spend 7 billion pounds ($11.2 billion) on its networks.
"Nearer term, there are some issues under the bonnet ... regulatory concerns are still overhanging, the performance of its Indian unit is debatable and, of course, the industry as a whole is famously competitive," Richard Hunter, head of equities at Hargreaves Lansdown Stockbrokers, said.
"Nonetheless, the outlook over the horizon is bright." (Editing by Susan Fenton)