a dosage question

Nursing Students Student Assist

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Specializes in Pediatric, Med/Surg, Psych, Hospice.

I need some assistance please. Say you are given a packet of medicine that states its has (250mg/5ml) and the packet states to add 10 ml of diluent. The doctors order is 500mg. Don't you mix the one packet with 10ml and administer that to make 500 mg or do you need 2 packets? This is a reconstition question I had on a skills test today and I feel like I am just freaking myself out over this.

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Specializes in Critical Care.

If the properly reconstituted drug is 10 mL and its concentration is 250 mg / 5 mL, you are correct.

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Specializes in Pediatric, Med/Surg, Psych, Hospice.

It is so strange of how you just lose all concentration when you are participating in your pass/fail skills check offs and how you start to second guess yourself. I really appreciate your help to anyone who can free my mind until get the results. I dont know how the students from Excelsior do there 3 day clinical. I think I would just go crazy. Thanks again.

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Specializes in med/surg, telemetry, IV therapy, mgmt.

Yes, you will need 2 packets of the medication. Adding the diluent doesn't increase the amount of medication that you have.

Dose on hand
: 250mg/5mL

Dose desired
: 500mg

500mg
(dose desired
)/250mg
(dose on hand)
= 2
(amount to give)

Since 10mL of a diluent must be added to each packet you will end up with 30mL:

2 x (5mL + 10mL of diluent) = 30mL

Sometimes these things are easier to figure out if you had the supplies in front of you and were looking at them. You might do what one of my algebra teachers used to constantly tell us about word problems: draw yourself a picture.

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Yes, you will need 2 packets of the medication. Adding the diluent doesn't increase the amount of medication that you have.

Dose on hand
: 250mg/5mL

Dose desired
: 500mg

500mg
(dose desired
)/250mg
(dose on hand)
= 2
(amount to give)

Since 10mL of a diluent must be added to each packet you will end up with 30mL:

2 x (5mL + 10mL of diluent) = 30mL

Sometimes these things are easier to figure out if you had the supplies in front of you and were looking at them. You might do what one of my algebra teachers used to constantly tell us about word problems: draw yourself a picture.

Daytonite, if 30mL (which would be 3 bottles of the medication not 2 since the bottle when reconstituted will have 10mL per bottle) was given you'd be giving 1500mg of the medicine! The bottle states 250mg per 5mL and to add 10mL to get that concentration. It doesn't state that there is already 5mL of fluid in that bottle. Its stating that the concentration when properly reconstituted will be 250mg/5mL. The bottle is empty of liquid except for the dry medicine that needs to be reconstituted.

The actual "picture" would be

Dose on hand 250mg/5mL

Desired dose 500mg

250mg/5mL=500mg/X (cross multiply to get ) 250X=2500 (isolate X) and get X=10mL

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Specializes in med/surg, telemetry, IV therapy, mgmt.

Oh, I get it. I misread the question. You are correct. What was actually in the packet? 500mg of dry medication only? If so, then, yes, you only add 10mL of diluent. Guess I should have drawn the picture!

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If there would be 250mg/5ml and you add 10mL you would have now, 2 doses of 250mg. So yeah, the "dry" medicine in the bottle would be 500mg total.

I kind of figured that you misread or misunderstood the question, it's not like you to give such a way off base answer :D

Not to hijack but I wanted to tell you Daytonite, that your knowledge is invaluable here at AN! You rock, momma!

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If there would be 250mg/5ml and you add 10mL you would have now, 2 doses of 250mg. So yeah, the "dry" medicine in the bottle would be 500mg total.

I kind of figured that you misread or misunderstood the question, it's not like you to give such a way off base answer :D

Not to hijack but I wanted to tell you Daytonite, that your knowledge is invaluable here at AN! You rock, momma!

I agree with Daytonite's original answer of 30ml's

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Specializes in cardiac ICU.

As I understand the question, you have one bottle that has 500mg of drug, and you need to add 10 ml of diluent. In the real world, if you have to add 10 ml of diluent to a bottle, it would state that the concentration of the drug, when properly reconstituted, would be 500 mg/10 ml. Trick question?

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Specializes in Critcal Care.

No, If the packet says add 10ml of diluent for make the concentration of 250mg/5ml, then you only need one packet. If 5ml is 250mg, then giving the full 10ml is 500mg as ordered by the physician.

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When I took Dosages and Calculations questions like yours were like the Five friends go shopping at five different stores in five different cities which one bought the peanut butter questions. Drawing pictures or using some kind of visual aid reeeeeeeeeeeeally helps.

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spoke with a friend of mine who is a pharmacist Gave her the order of 500mg and a bottle that reads 250mg/5ml and to reconstitue with 10mL. The dosage would be 10mL which would be one bottle/packet.

She even did a "dummy" script to see what the computer would do for dosage and it read 10mL .

So giving the pt 2 bottles/packets would be giving the pt 1000mg of the drug, since each bottle contains 500mg.

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