<prompt> FTU is a measure of:Area involved in severe drug reactionsAmount of topical drug to be appliedMucosal involvement in pemphigusConcentration of drug in topical preparations  <response>: An approximate practical measure of topical medication is the fingeip unit, the quantity of ointment, extruded from a tube with a nozzle of 5 mm diameter extending from the distal crease of the forefinger to ventral aspect of the fingeip. This unit weighs approximately 0.49 g in males and 0.43 g in females and covers, on average, an area of approx 300 cm2. 