Pfizer, the world's largest drugmaker, said Wednesday that it paid about $20 million to 4,500 doctors and other medical professionals for consulting and speaking on its behalf in the last six months of 2009, its first public accounting of payments to the people who decide which drugs to recommend. Pfizer also paid $15.3 million to 250 academic medical centers and other research groups for clinical trials in the same period. While other pharmaceutical companies have disclosed payments to doctors, Pfizer is the first to disclose payments for the clinical trials. A spokeswoman for Pfizer, Kristen Neese, said most of the disclosures were required by an integrity agreement that the company signed in August to settle a federal investigation into the illegal promotion of drugs for off-label uses. Dr. Freda C. Lewis-Hall, Pfizer's chief medical officer, characterized the disclosure and Web site as part of 'a march to disclosure' that the company started in 2002. Pfizer is the fourth major drug company to make such disclosures, following Eli Lilly, Merck and GlaxoSmithKline. 'All of them are welcome, but none of them is a replacement for a single national database,' said Allan Coukell, director of the Pew Prescription Project, an initiative of the Pew Charitable Trust. Beginning in 2012, drug and medical device companies will be required to disclose payments to doctors of more than $10, with the first report available in 2013. The Physician Payment Sunshine Act was passed as part of health care reform. 