ZURICH (Reuters) - Novartis AG (VTX:NOVN.VX - News) is likely to be the latest drugmaker to show it too has been hit by a collapse in sales of pandemic flu medicines when it posts its first-quarter results on Tuesday. But the group, which has just closed its buy of eyecare group Alcon, is still expected to show robust demand for its other drugs and investors will be keen to see how its recently launched multiple sclerosis drug Gilenya, is fairing.