Situation 1: (main formula to always remember)

The doctor orders 5mg of drug "A".  Drug "A" comes in a vial of 15mg in 30mL.  How many mL do I give?

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Formula: Dose to give/order (mg) x Volume (mL)
                        Concentration in vial (mg)

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It is simple.  Just remember that the doctors order always goes on top.  In this case 5mg.  When you pick out drug "A" it will have 15mg in 30mL written on it.  You cannot place two mg numbers on the same line.  So the 15mg has to go on the bottom since the 5mg order went on top.  This leaves you with 30mL that has to go on top in the volume space. JUST REMEMBER THAT ONLY ONE MG (ORDER) CAN BE ON TOP.

Also note the following.  The drug comes in 30mL and has 15mg.  To find the concentration of the drug per mL just divide 30mL by 15.  This will give you a concentration of 2mg/1mL. 

In the formula you can use 15mg in 30mL or 2mg in 1mL and get the same final answer to the problem.

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Formula in this question is:   5mg x  30mL      
                                                       15mg

The answer is 10mL.  The mg's cross out leaving you with mL as your final labeling unit.

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Situation 2:

The doctor orders 2mg/min (So the doctor wants 2mg of the drug administered per minute = mg/min) of drug "C" to be infused.  The drug is supplied with 1500mg in a 500mL IV bag.  How many drops per minute are needed?

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Formula:  Do situation 1 as listed above.  At the end multiple the answer by 60drops/min.  This is the answer.

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2mg/min is the doctors order and goes on top.  Then look at the drug supply.  The 1500mg must go on bottom because you cannot place two mg numbers on the same line.  The only place for the 500mL is on top in the volume space. 

2mg/min x 500mL     
        1500mg

The answer so far is  0.66mL/min (the mg on the top and bottom cross out each other leaving you with mL/min.

To finish the problem take the 0.66mL/min times a 60 drop/mL IV set.    0.66mL/min x 60drop/mL = 39.6drops/min final answer.  The ml in 0.66 and the mL in the drip set cross out leaving you with Drops/Min.

Situation 3:

Doctor orders 1000mL of drug A given over 2 hours with a 10drops/mL IV drip set.

Once again very simple.

1) Always convert hours to minutes right away.  So 2 hours turns into 120 minutes.

2) Order always goes on top:  1000mL  this leaves TIME TO GIVE DRUG so 120 minutes goes on bottom.

        1000mL            This equals 8.33mL/min SO FAR.
        120 min

3) Take the 8.33mL/min and multiply by the drip set which is 10drops/mL.  This equals 83.3drops/min.  The mL in 8.33 and the mL in 10drops/mL cross out.  Leaving you with Drops/Min.  83.3drops/min is the final answer.

Situation 4:

The doctor orders 3mg/kg of drug Q.  The patient weighs 180 pounds.  Drug Q is stored 300mg in 30mL.  How many mL do I give?

1) Always convert pounds to kg's right away. 1kg is 2.2 pounds.  So take 180 pounds and divide by 2.2 and the answer is 81.8kg.  Just remember that kg are always smaller than pounds.  So the number should go down.

2) Next restate the doctors order of 3mg/kg as;  3mg x 81.8kg = 245.5mg.  245.5mg is the true doctor order.

3) Same set up as situation 1.  Order is 245.5mg and always goes on top.  So 300mg has to go on the bottom because you cannot have two mg's on the top line. The 30mL goes on top as volume.

245.5mg x 30mL     
       300mg

This equals 24.55mL.  This is the final answer.  So of the 30mL of drug only give 24.55mL of it.

Situation 5:

The doctor orders 2mg/kg of drug P given.  He wants the drug mixed into a 500ml IV bag and given over 1.5 hours using a 60drop/mL IV drip set.  What is the drip per minute to give this drug over 1.5 hours.  The patient weight is 210 pounds and the drug P is stored 600mg in 40mL.

This is simple if you work it out step by step.

1) What is the doctors true order; 2mg/kg mixed into an IV bag and given over 1.5 hours.  So first convert the weight.  210 pounds divided by 2.2 = 95.45kg.  So the doctor wants 190.9mg mixed into an IV bag.  The kg is removed.

2) We need to find out how much of drug P to put into the IV bag. Use situation 1's formula.

Formula         190.9mg x 40mL              
                                600mg                  Answer is 12.72 mL  SO FAR.  The mg's from the bottom and top cross out.

3) So we need to add 12.72 mL of drug P to a 500mL bag.  (For the sake of argument at this stage you should remove 12.72Ml of fluid from the 500mL IV bag so that when you mix in the 12.72mL of drug P you still have a 500mL IV bag.  If you just add 12.72ml of drug P to the 500mL IV bag you will truly have 512.72ml total.  So for this problem we still are only dealing with a 500mL IV bag which includes 12.72mL of drug P.)

4) So now to situation 3. Drug given over time.  Covert the 1.5 hours to 90 minutes.  So the doctor wants the 500mL IV bag with drug P given over 90 minutes using a 60drop/mL IV drip set.

Formula: Order always on top.        500mL               
                                                            90min                SO Far the answer is 5.55mL/min.  Now we have to multiply this number by the drip set (60drop/mL)

So 5.55mL/min x 60drop/mL = 333drops/min.  The mL's cross out.  (this drip rate is the right answer but the number I used are a little unrealistic)

Recap: In order to give 2mg/kg of drug P over 1.5 hours this is what we did.

1) Placed 12.72mL of drug P in a 500mL IV bag.

2) Took the 500ml IV bag and divided it into 1.5 hours (90 minutes).  Then multiplied by the drip set. 

Situation 6:

1000 ml of Saline Solution is to be infused intravenously. The set has a drop factor of 15 drops/mL and is set at 40 drops/min. How long will this infusion take to finish?

1) You need to figure out how many mL's are being given per minute.  Take your drip rate of 40 drops/min and divide into drip set of 15 drops/mL

                        40 drops/min
                        15 drops/mL       This equals 2.66 mL's are being given per minute to the patient.

2) Divide the order of 1000mL to be given by 2.66 mL/min and you get:  375.9 min.  The mL's cross out leaving minutes.  Now convert the minutes back to hours and you get 6.26 hours and that converts to 6 hours and 15 minutes.

3) Final answer is 6 hours and 15 minutes.