Im having trouble understanding these math questions for medication reconstitution

Published

Erythromycin Ethylsuccinate oral suspension bottle instructs you to add 53 mL of water and shake vigorously. This makes 100 mL suspension for a concentration of 200mg per 5mL. Refrigerate after mixing.

pt care orders read: give 550mg of Erythromycin Ethylsussiante by mouth every 8 hours. How much will you administer?

Ceftriaxone 1 g reconstituting options, option 1: add 3.6 mL of sterile water to obtain 250mg/mL concentration

Ordered Ceftriaxone 750 mg IV q 6 h How much will you draw up?

Ordered Ceftriaxone 450 mg IV q 4 h How much will you draw up?

Up Vote Up Vote ×
Specializes in Medical and general practice now LTC.

What are your thoughts? Just pick one and explain your thoughts

Up Vote Up Vote ×
Just now, Silverdragon102 said:

What are your thoughts? Just pick one and explain your thoughts

Okay, I may be wrong but the equation is d/h*q and for the first one, I went 550/200*5 to get 13.75 which, I rounded to 13.8mL and for the second ones, I went with 750/250*1=3mL and 450/350*1=1.285 rounded to 1.3mL

Up Vote Up Vote ×
Specializes in Medical and general practice now LTC.

For the last one I get 1.8 ml. Don’t forget that the direction you gave was 250mg/ml and you did 350. Other 2 doses are same as what I got

Up Vote Up Vote ×
9 hours ago, Silverdragon102 said:

For the last one I get 1.8 ml. Don’t forget that the direction you gave was 250mg/ml and you did 350. Other 2 doses are same as what I got

Thanks

Up Vote Up Vote ×
Specializes in Cardiac, Perioperative care, research.

1. 200÷5=40, 550÷40=13.75 rounded off to 13.8
2. 1ml=250, 3x250=750

3. 1m=250, 450÷250=1.8

Up Vote Up Vote ×
+ Join the Discussion