fluid dosage calculations

A suspension contains phenytoin 125 mg / 5 ml. How many milligrams/grams of phenytoin are in 40 ml of the suspension? a) 5000 mg b) 750 mg c) 450 mg d) 1 g

1. 125 mg / 5 ml divided by 5 = 25 mg / ml we are dividing by 5 in order to isolate the dosage 2. 25 mg / ml x 40 ml = 1000 or 1 g ANSWER : 1 g

MD writes an order for Posaconazole 75 mg by mouth once a day. Pharmacy dispenses you with 20 mg/ 2 ml. How many ml will you administer per dose? a) 3 ml b) 5 ml c) 1.5 ml d) 7.5 ml

1. 20 mg / 2 ml divided by 2 = 10 mg / ml we divided by 2 in order to isolate the variable 2. We take the D = 75 mg and we divide it by 10 mg / ml which gives us 7.5 ml ANSWER : 7.5 ml

A solution contains fluoxetine 20 mg / 5 ml. How many milligrams of fluoxetine are in 40 ml of solution? a) 160 mg b) 400 mg c) 2 mg d) 0.5 mg

1. 20 mg / 5 ml divided by 5 = 4 mg / ml we are dividing by 5 in order to isolate the dosage 2. 4 mg x 40 = 160 mg we are multiplying instead of dividing because there is only one conversion factor present which is mg in this case scenario ANSWER : 160 mg

30 mg of Tofranil is ordered; available solution contains 25 mg / 2 ml. How much will you administer? a) 1 ml b) 1.4 ml c) 2.8 ml d) 2.4 ml

1. 25 mg / 2 ml divided by 2 = 12.5 mg / ml dividing by 2 gets rid of the 2 in front of the ml so that you are solely left with one dosage 2. 30 mg divided by 12.5 mg / ml = 2.4 ml it's always ordered over have which is why we are dividing the 30 by the 12.5 ANSWER : 2.4 ml

MD writes an order for Demerol oral suspension 50 mg by mouth every 6 hours for pain. Pharmacy dispenses you with 25 mg/ 2 ml. How many teaspoons with you give per dose? a) 200 ml b) 250 ml c) 0.8 tsp d) 0.5 tsp

1. 25 mg / 2 ml divided by 2 = 12.5 ml 2. 50 mg divided by 12.5 mg / ml = 4 mg 3. 100 mg = 0.02 tsp 4. 0.02 x 4 = 0.8 tsp ANSWER : 0.8 tsp

MD writes an order for Viscous Lidocaine 15 mg by mouth every 4 hours as needed for sore throat. Pharmacy dispenses you 30 mg/3ml. How many ml with you administer per dose? a) 1.5 ml b) 6 ml c) 3 ml d) 0.5 ml

1. 30 mg / 3 ml divided by 3 = 10 mg / ml we are dividing by 3 in order to isolate the dosage 2. We now take the D = 15 mg and divide it by the 10 mg/ml which comes out to be 1.5 ml The question is asking for ml therefore the answer will be in ml ANSWER : 1.5 ml

MD writes an order for Ibuprofen 300 mg by mouth every 4 hours for pain. Pharmacy dispenses you with 50 mg/ 2.5 ml. How many ml will you administer per dose? a) 15 ml b) 5 ml c) 24 ml d) 18 ml

1. 50 mg / 2.5 ml divided by 2.5 = 20 mg / ml we divided by 2.5 in order to isolate the variable 2. D = 300 mg divided by 20 mg / ml = 15 ml ANSWER : 15 ml

MD writes an order for Mucomyst 300 mg by mouth one dose before heart cath. Pharmacy dispenses you with 600 mg/2 ml. How many ml will you administer per dose? a) 2 ml b) 1/2 ml c) 1 ml d) 1.5 ml

1. 600 mg / 2 ml divided by 2 = 300 mg / ml dividing it by 2 gets rid of the 2 in front of the ml so that you are solely left with one dosage 2. 300 mg divided by 300 mg/ml = 1 ml dose The question is asking for ml so you want to isolate the ml ANSWER : 1 ml

MD writes an order for Valium 1 mg by mouth via PEG tube. Pharmacy dispenses you with 3 mg/ml. How many ml will you administer per dose? a) 2 ml b) 5 ml c) 0.3 ml d) 0.6 ml

1. D = 1 mg : H = 3 mg/ml 2. 1 mg divided by 3 mg/ml = 0.3 ml ANSWER : 0.3 ml