Strong performances in Hikma Pharmaceuticals' injectable drug business drove the company's annual pre-tax higher by over 20%, though a warning about the impact of the US dollar on 2015 revenues was perhaps behind an initial fall in the shares.The Jordanian drugmaker reported a 21% year-on-year increase in pre-tax profit to $362m (£240.3m), while revenue rose 9% to $1.49bn, exceeding management's guidance of revenue growth of around 7% for the year.A 51% increase in revenue in the US, drove revenue in the group's injectable drug business higher by 33% to $713m, having raised its full-year revenue growth forecast for the unit to 25% late in 2014 , with adjusted operating margins of above 35%.The injectable drug business accounted for 48% of total sales at the FTSE 250 group, a 9% increase year-on-year.Hikma, which is set to join the FTSE 100 index later in March, reported adjusted operating margin of 37.2% and said that it was confident of delivering a similar performance in 2015, forecasting adjusted operating margins to be around 35%.But it cautioned that the storming US dollar looked like it could dent 2015 revenues by around 3%."Hikma should now be in a better position to weather the eventual resolution of current drug shortages and continue to grow the sterile injectables business albeit at a slower pace near term," analysts at Shore Markets said in a note on Wednesday.However, the broker warned that a stronger-than-expected performance in 2014 made it for a tougher comparator in 2015.Hikma shares were down 2.76% to 2,250.00 at 08:41 on Wednesday.