Question

Compounding Questions:

1. Calculate the amount of each of the compounds that you will need to use during the lab. Note: You will have to perform a geometric trituration on the urea using water in order to levigate it,

Urea - 10% w/w

White Petrolatum - qs to 25 g

2. Calculate the amount of each of the compounds that you will need to use during the lab.

FD&C Yellow #5 - 0.2% w/w

Lidocaine HCl - 2% w/w

White Petrolatum - qs to 30 g

Answer 1

1) Urea 10% w/w means 10gms of urea in 100 gms of white petrolatum

Here it is mentioned white petrolatum quantity sufficient to 25 g

So 1/4th in 100 gms.is 25 gms.

So urea for 10% in 25 g required is 2.5 gms of urea + 22.5 gms white petrolatum or 2.5 gms urea mixed in white petrolatum and makeup up to 25 gms.

2) Here the final makeup is done by white petrolatum that is up to 30 gms (100/3)

So FD&C yellow #5 and lidocaine HCl are calculated accordingly

FD& C yellow 0.2%w/w that means 0.2 gms in 100gms of solvent

So according to 30g of white petrolatum FD&C yellow #5 required 0.066/0.067 gms. (0.2gms/3)

Similarly, lidocaine HCl required 0.66/0.67 gms (2gms/3)   

Take the required quantity of FD& C and lidocaine HCl and makeup to 30gms with vehicle white petrolatum.