Azelastine hydrochloride is an antihistamine nasal spray. a standard size container holds one fluid ounce (oz.) of the liquid. you are searching for this medication in a european drugstore and are asked how many milliliters (ml) there are in one fluid ounce. using the following conversion factors, determine the number of milliliters in a volume of 1.46 fluid ounces: 1 gallon (gal) = 128 oz., 3.785 x 10-3 cubic meters (m3) = 1 gal, 1 ml = 10-6 m3.