Mumbai: The rupee struggled to make headway after a two-day climb and backtracked to end sharply lower by 43 paise to 72.63 against the US dollar after crude prices soared ahead of impending US sanctions on Iran. It opened lower at 72.47 from weekend close of 72.20 at the forex market. The local unit lost further ground to hit a session low of 72.73 in mid-afternoon session before concluding the day at 72.63, revealing a steep loss of 43 paise. PTI