Medication calculations There are 4 basic steps to solving proportion problems: 1) Set up a known ratio. 2) Set up a proportion with known and desired units. Use x for the quantity that is desired or unknown. 3) Cross multiply. 4) Solve for x. Example: Dose Ordered: Medication B 15 mEq po every day. Available: Medication B 10 mEq/5ml. How many ml's will you give? a) Set up proportion. (Units are matched therefore no need to convert- mEq to mEq and ml to ml) b) Cross multiply and solve for x. 10??? 5?? = 15??? ??? 10x=75 x= 75 10 15 mEq= 7.5 ml Calculating IV Flow Rates: To find hourly rate (stated in mls per hour) Total volume of solution in ml’s = x ml’s Total amount of time in hours Example: 1000 cc IV solution ordered to infuse over 8 hours. 1000 ml = 125 8 hrs. Answer: 125 ml/hour Example: 1000 ml solution to infuse over 6 hours