Percentage concentration

% w/w(weight)----------active ingredient and base have same unit of weight. 1%=1gm of active ingred per 100gm total product.1% w/w= 1gm/100gm

%v/v(volume)-------solute(active drug) and solvent(inactive base) have same unit of volume. 1% v/v=1ml/100ml

%w/v(weight/volume)-------solute is in the weight grams and solvent is in volume ml.1% w/v=1gm/100ml

• 1.4g of phenol mixed with 9g of glycerin. What is % concentration of phenol in this product?

1.4+ 9g =10.4g1.4/10.4*100=13% w/w

4g KCL is dissolved in base to make total of 25ml. What is per concentration of final product?4/25*100=16%w/v

10ml glycerin is dissolved in enough water to make 73ml of final solution. Calc % of strength of glycerin.

10/73*100=14% v/v

• How much KCL is needed to make 240ml of a 10% solution?

• 10gm/100ml=x gm/240ml• X=24g of kcl

alligations• Using 2 different concentrations of a drug to arrive

at final concentration somewhere between the 2 in stock.

• Dr orders 30g of 15% hydrocortisone cream. Pharmacy has cream in 20% and also 2%. Alligation will combine these to get 30gm, of 15%.

• See board pg158-------

Ratio concentrationsNormally this uses epinephrine or potassium

permanganate.You must memorize-------1:1000------1mg/ml1:100--------10mg/ml1:10---------100mg/ml

Rx is 3mg of epi. Pharm stock is 1:100 solution. How may ml will be given?

10mg/ml= 3mg/xml10x mg=3mgX=.3ml

• Rx 2.5ml inj of 1:1000 epi is given. How much drug did pt get?

• 1:1000=1mg/ml• 1mg/ml=x mg/2.5ml• X =2.5mg

Parenteral calculation• Done for IV drips. This has greater risk of immediate

pt harm if wrong.• Flow rate=vol/time• Pt gets 1L of IV sol over 3 hours. What is flow rate?• Flow rate=1000ml/3hrs• Fr=333ml/hr --- this means 5.55ml/min

• How many hours will 1L of D5W last when flow rate is 125ml/hr?

• Time=vol/rate• time=1000ml/125ml• Time=8hr

• Vol=time *rate• Hwo many ml needed to run IV at 60ml/hr for 12

hours?• Vol=12hrs*60mlper hour• Vol=720ml

• Gtt/min=volume to be infused *drip set rate/infusion time in minutes

• Rx is d5w at 125ml/hr. admin set is 10gtt/ml. How many gtt/min should we use?

• Gtt/min= 125ml*10gtt/60min• Gtt/min=1250/60• Gtt/min=20.8 ~21gtt/min

• Gtt/min=volume to be infused *drip set rate/infusion time in minutes

• 300ml of d5w given at rate of 75ml/hr. admin set gives 10gtt/ml.how many gtt/min should we use?

• Gtt/min=vol infused*drip rate/infusion time(min)• Gtt/min= 75ml*10/60• Gtt/min=750/60• Gtt/min=12.5gtt/min ~13ggt/min

• https://www.youtube.com/watch?v=CujuVNn7ROY• alligations• https://www.youtube.com/watch?v=CujuVNn7ROY• Drip rate• https://www.youtube.com/watch?v=CujuVNn7ROY• Percents• https://www.youtube.com/watch?v=CujuVNn7ROY• Powder volume