Around 2,000 doctors at 20 hospitals in the national capital today launched an indefinite strike, demanding adequate life saving drugs, security at workplace and timely payment of their salaries. The strike by resident doctors at 20 hospitals run by the central and Delhi governments and civic corporations including Ram Manohar Lohia Hospital, Safdarjung Hospital, Lady Hardinge Medical College, Maulana Azad Medical College affected services at the facilities.