Calculation Trouble

[sarahsrs]

Hi, I've just started Year 1 as a student pharmacy technician and I am confused by the following calculations...

How many milligrams of drug Y are contained in 250ml of a 0.05% w/v solution of drug Y in water?

and

Calculate the amount of drug present in 300ml of a 4% w/v solution of that drug?

Is w/v weight/volume? I don't really know how to go about solving these.

There is also a question which reads: a child of 4 years old requires the maximum BNF dose of promethazine hydrochloride by the oral route.
-what is the maximum dose per day?
- what volume of elixir should be supplied for 14 days treatment?

I found Promethazine in the BNF and the Children's BNF and I found it to say for children aged 2-5 years 5-15mg daily in 1-2 divided doses. There is a higher dose possible for premedication but the question doesn't mention that. Is promethazine only available as 5mg/5ml?


Any help would be really appreciated, thanks in advance xxx

[Fleegle]

1) 125mg
2) 12g
3) Yes
4) 15mg
5) 210ml (at maximum daily dose)
6) As a daily dose is specified, a pre-med dose is not applicable.
7) Base your answer on Phenergan 5mg/5ml

Percentage solution - Wikipedia, the free encyclopedia

[sarahsrs]

Thank you very much.

[sarahsrs]

That link has made everything become clear, thank you!