Shares in Reckitt Benckiser sank to the bottom of the FTSE 100 despite the household goods maker posting a rise in earnings and sales for the first quarter.The firmsaid operating profits rose by 14% to £461m. Revenues were up 5% to £2bn.Reckitt said its strong performance was helped by a focus on 17 'Powerbrands' which include Finish dishwasher tablets and Harpic toilet cleaner.'This result was supported by successful new product initiatives, and significant investment in media and marketing across our Powerbrand portfolio' chief executive Bart Becht said.However, while confident on 2010, he warned that the company, 7% of whose revenues come from the heroin dependency treatment Suboxone, could come under pressure.'These results reinforce our confidence in achieving continued good growth in 2010, notwithstanding potential generic competition to Suboxone in the US,' he said.