Question

1. You have available a 2 mL ampule of procainamide (Pronestyl) labeled 500 mg in 1 mL. 0.1 grams of procainamide hydrochloride must be prepared. How many mL of the drug should you prepare?

2. 200 mcg of clonidine (Catapres) has been prescribed. Clonidine is available in 0.1 mg scored tablets. How many tablets should be administered?

3. 90 mL of ¼ strength Ensure must be prepared for a tube feeding. You have available full strength Ensure. To prepare the feeding, you dilute ___ mL of the full strength Ensure with ___ mL of water.

4. 225 of ¼ strength Criticare HN must be prepared for a tube feeding. You have available full strength Criticare HN. To prepare the feeding, you dilute ___ mL of the full strength Criticare HN with ___ mL of water.

PLEASE HELP WITH THESE IM SO LOST! Please show how you solved it with dimensional analysis.

Thank you!

Answer 1

1.Available dose=500mg/ml

Desired dose =0.1 grams=100mg. (1 gram=1000mg)

Let 'x' ml contains 100mg of peocainamide.

So, 500mg/1 ml= 100mg/'x' ml

Ie; The desired amount, x ml=(100/500)*1=0.2 ml

2.Available dose=0.1mg/tab

Desired dose =200 mcg=0.2 mg. (1mg=1000mcg)

Let 'x' tablets contain 0.2 mg of clonidine.

0.2/x=0.1/1

So,Desired amount,the number of tablets that contain 0.2 mg clonidine =(0.2/0.1)*1=2 tablets.

3.Desired dose=90 ml of ^1/₄  strength=90 ml of 25% ensure

Available dose= 100% ensure

Lets apply the formula of dilution for making mixed volumes of specific concentrations

V₁C₁=V₂C₂  where V is the volume and C is the concentration.

Here,

V₁₌?(the amount of 100% ensure solution needed to start with)

C₁=100%

V₂=90ml( the amount of final solution)

C₂=25%

So the amount of 100% ensure needed to make 90 ml of 25% ensure solution=(V₂*C₂)/C₁=(90*25)/100=22.5ml

Amount of water needed=V₂-V₁=90-22.5=67.5 ml

4.available dose=100% solution of criticare HN

Desired dose=225 ml of 1/4 solution of criticare HN=225 ml of 25% solution of criticare HN.

Applying the formula of dilution,

V₁=?(volume of 100% solution to start with)

C₁= 100%

V₂=225 ml

C₂=25%

So,the volume of 100% criticare HN needed to make 225 ml of 25% solution =(V_2*C₂)/C₁=(225*25)/100=56.25ml

Water needed to dilute the drug=V₂-V₁=225-56.25=168.75 ml