Question

A patient with a corneal ulcer brings you a prescription for ofloxacin ophthalmic solution 0.3%. The prescription states that the patient is to instill 2 drops into the left eye every 30 minutes while awake for 2 days, then 2 drops every 1 hour while awake for the next 7 days, then 2 drops every 6 hours for the next 10 days. The patient states that he sleeps 6 hours per night. You determine that the ofloxacin ophthalmic dropper container delivers 20 drops per milliliter. Each bottle of ofloxacin contains 5 mL How many bottles of ofloxacin should you dispense? How many milligrams of ofloxacin are contained in each drop? II.

Answer 1

I.Given

1 bottle=5ml

1ml=20drops

Concentration :0.3% which means 3mg/ml

Patient sleeps for 6 hours ,so he is awake for 18 hours

Now for first 2 days to instil 2 drops/30 minutes

So for 18 hours = 36 times in one day

As 1ml=20 drops

Then 2 drops=??ml

Cross multiply and divide

=0.1ml (2÷20)

So for one time instilation  2 drops =0.1 ml of the solution

Therefore for 36 times=??

3.6ml (36×0.1)

So in Day 1: 3.6ml will be instilled

Again in Day 2:3.6ml will be instilled

(In first 2 days 7.2ml solution will be used)

To calculate for next 7 days

Order 2 drops every hourly

So it is 18 times a day

As 1time instillation dose is 0.1ml

Therefore 18 times=??ml

=1.8ml/ day (18×0.1)

For seven days 1.8ml×7=12.6 ml

(Next 7 days 12.6 ml will be used)

To calculate for next 19 days

Order 2 drops every 6 hours ( 3 times a day as patient is awake for 18 hours)

1 time =0.1 ml

Then for 3 times=??

=0.3ml/day

Now 10 days= 3ml (10×0.3)

(for next 10 days 3ml will be used )

Now to calculate the total number of bottles

7.2ml+12.6ml+3ml=22.8 ml

As bottle =5ml

Then 22.8 ml=??

=4.56 bottle that is 5 bottle

Ans:5 bottle to be dispensed

II.As the concentration is 0.3% (3gm/ml )

As 2 drops =0.1ml

Now to calculate for 0.1ml

0.3gm (3×0.1÷1)

Ans:0.3gm /2 drops