The British drug maker GlaxoSmithKline will no longer pay doctors to promote its products and will stop tying compensation of sales representatives to the number of prescriptions doctors write, its chief executive said ..., effectively ending two common industry practices that critics have long assailed as troublesome conflicts of interest. The announcement appears to be a first for a major drug company - although others may be considering similar moves - and it comes at a particularly sensitive time for Glaxo. It is the subject of a bribery investigation in China, where authorities contend the company funneled illegal payments to doctors and government officials in an effort to lift drug sales. For decades, pharmaceutical companies have paid doctors to speak on their behalf at conferences and other meetings of medical professionals, on the assumption that the doctors are most likely to value the advice of trusted peers. But the practice has also been criticized by those who question whether it unduly influences the information doctors give each other and can lead them to prescribe drugs inappropriately to patients. Under the plan, which Glaxo said would be completed worldwide by 2016, the company will no longer pay health care professionals to speak on its behalf about its products or the diseases they treat to audiences who can prescribe or influence prescribing." It will also stop providing financial support directly to doctors to attend medical conferences, a practice that is prohibited in the United States through an industry-imposed ethics code but that still occurs in other countries.