Lessons · Pharmacy · puffs in a canister
Puffs in a canister
The canister's label says how many actuations it holds, and the days' supply is that number divided by the puffs used in a day.
Hone is a place to practise a career, one idea a day. This is one of its lessons, written out in full and free to read without an account.
In beta. This lesson was written for Hone and has not yet been checked by a licensed pharmacist. Practice material, not professional advice. What that means.
What it is for
A canister is not a bottle you can count, so the only number you have is the one printed on the box. A patient told the wrong days' supply runs out mid-week, and a rescue inhaler that runs out is not a small problem.
How to think about it
Puffs a day first: the puffs in one dose times how many doses a day. Then divide the actuations by it, and round DOWN to whole days.
Worked example
2 puffs qid = 2 x 4 = 8 puffs a dayThe dose is in puffs, so the day's worth is in puffs too.
200 actuations / 8 = 25 daysThe canister divided by a day's worth.
120 actuations / 2 puffs a day = 60 daysA smaller canister on a smaller sig lasts longer.
A prn inhaler is worked from the maximum the sig allowsOtherwise there is no number a day to divide by.
Your turn
A canister holds 60 actuations and the sig uses 4 puffs a day. Write the days' supply.
60 / 4 = days
Solve one, graded on the server
The trap
Counting doses instead of puffs. Two puffs four times a day is four doses and eight puffs, and the canister is counted in puffs.