Re: calculations- will use this as a template for rest of questions I have.

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Dear EK and ALL,

Here is a bit of background:

First of all syringes are available as:

0.5, 1, 3, 5, 6, 10, 12, 15, 20, 25, 30, 35, 50 and 60 ml

There are also 100's for inseminating bovine, but I have not seen this size used

in hospital pharmacy.

Secondly you always use the smallest size syringe possible for best accuracy and

least error, EXCEPT when you are making chemotherapy drugs. Pressure can build

up during the preparation of chemotherapy. Therefore since pressure can build

up when during chemotherapy preparation Negative pressure is maintained for

chemotherapy products.

IF pressure is built up it is said to be positive pressure. In this

case the plunger of the syringe could move backwards very quickly and with much

force which could blow it out of the syringe towards someone or something, which

could injure someone's eye or shatter a glass spilling or contaminating an area

or ???

Negative pressure is maintained for chemotherapy products

Positive pressure is maintained for non-chemotherapy products

University of Kentucky CE states " DO NOT use syringes whose gradations are

greater than twice the volume being measured " . YET you need to be sure that you

have at least 1.5 the amount that you are going to measure to take into

consideration the pressure.

Example if the doctor orders 2.5 ml than be sure you are using a 5ml syringe,

but not bigger. Using a large syringe would reduce accuracy. Using a smaller

syringe will not allow for negative pressure.

All that having been said you are now ready to tackle the mathematical

questions. Using ratio/proportion is always a safe bet/choice when solving these

types of problems:

1. A patient needs a 125mcg dose. use the 50mcg/ml vial. how much is need for

the dose and what size syringe is needed?

50 mcg-------125 mcg

--------- = -----------

1 ml----------X ml

1 x 125

--------- = X ml

50

X ml = 2.5 ml

2. A patient needs 800mg for use in an iv. use the 100 mg/ml vial. how much is

need for the dose and what size syringe is needed?

100 mg---------800 mg

----------- = -----------

1 ml-----------X ml

1 x 800

--------- = X ml

100

X ml = 8 ml

3. A patient needs 3300 mg for an ivpb. use the 330 mg/ml vial. how much is need

for the dose and what size syringe is needed?

330 mg---------3300 mg

----------- = ------------

1 ml------------X ml

1 x 3300

----------- = X ml

330

X ml = 10 ml

4. A patient needs 200mg of chemotherapy. Use the hazardous liquid vial. How

much is need for the dose and what size syringe is needed?

The concentration for the chemo drug is not given in this problem.

Since I do not have the concentration for the drug, I can not calculate how many

ml are needed. However what ever number of ml are needed multiply that by 1.5

and also by 2. Choose a syringe that will allow you to measure the amount of

drug in ml some where between the two numbers.

Example if 200 mg equates to 4.7 ml

4.8 x 1.5 = 7.2 ml (this size syringe is not available)

4.8 x 2 = 9.6 ml (this size syringe is not available)

The BEST available size syringe is a 10 ml syringe. It is only slightly over the

double that University of Kentucky says not to use. It will be fine.

Hope this helps,

Jeanetta Mastron CPhT BS

Pharm Tech Educator

Founder/Owner

>

> Hi, can you please answer and show me how you got the answer. I have 4

different ones, that I will use as a template for me to actually do the rest of

my questions. Thank You

>

> 1. a patient needs a 125mcg dose. use the 50mcg/ml vial. how much is need for

the dose and what size syringe is needed?

>

> 2. a patient needs 800mg for use in an iv. use the 100 mg/ml vial. how much is

need for the dose and what size syringe is needed?

>

> 3. a patient needs 3300mg for an ivpb. use the 330mg/ml vial. how much is need

for the dose and what size syringe is needed?

>

> 4. a patient needs 200mg of chemotherapy. use the hazardous liquid vial.

> how much is need for the dose and what size syringe is needed?

>

>

> THANKS AGAIN!!

>