drug calculations

[denicu]

anyone can recommend a website for drug calculations esp for small dosage. For ex when dose ordered comes out to 0.07ml and you have to add saline and end up giving 0.7 ml. Meds such as lasix, phenobarb, decadron. Unfortunately, there are units where you still have to make your own medications. Hope my fellow nurses understand what I am asking. Thanks.

[NICU_babyRN, BSN, RN]

I know what you are talking about when you refer to drawing up your own meds but what kind of calculations do you need exactly? For example: We usually draw up the 0.07ml into a TB syringe and then add saline to it to make it 0.7ml total. So we don't dilute the lasix or other drug in it's original vial. We draw up only what we need from it.

[denicu]

For ex dose ordered is 5mg of phenobarb. Med comes up 65mg

/ml. Dose calculation is 0.07ml. Taking 1 ml of phenobarb and mixing it with 9ml of s/w. The med is now 65mg to 10ml and dose to be given is now 0.7ml. this was how i was thought to mix it.

[helicoptergal, BSN, RN]

Hi in my unit we use the 20% rule or drawing up 20% of what the drug concen. to make your drug calculation the most precise. As for example a Phenobarb concen. is 65mg/1ml. For example your dose is 7mg. So 20% of 65mg/1ml = 13mg. We then will reconstitute our solution to 1ml. And do the calculation as follows 7mg/13mg x 1ml = 0.54ml and push down the 1ml to the o.53 in a 1ml syringe. We also change the needles between reconstitutions, as the needle hold some med. The same calculation can apply to all your other meds. :-)

[denicu]

Every where does things differently and thats why I love doing agency and working in different units. You quickly learn there are more than 1 way to do things. The 20% rule is a first for me but I am a little confused -do you draw up the 1 ml from the phenobarb -because you say you reconstitute 1 ml. Can you clarify that for me? Thanks.

[helicoptergal, BSN, RN]

Sorry about that. Dose is 7mg. You draw up 0.2mg or 20% of the 65mg/1ml concen. So 0.2mg = 13mg. Than reconstitute to 1ml and change needles. Than your new calculation is 13mg/1ml so 7mg/13mg x1ml = 0.54ml. Push out the 1ml to 0.54ml and that will = 7mg and then follow your protocols of reconstitution. I reconstitute again to =1ml. Hope this helps.

[BittyBabyGrower, MSN, RN]

We have specific guidelines on how to dilute things that aren't done by pharmacy. We rarely, if ever, add anything to a med. I'd hate to have to do what you all do!

[denicu]

I understand now. Actually, in this unit pharmacy makes up most of their meds but this was an emergency so we got the med out of the pyxis instead of waiting for pharmacy to make it.

[misscherie]

I know this is an old post but in case others are searching this for drug calculation help, heres an excellent website that may help you :)

http://www.manuelsweb.com/nrs_calculators.htm

[trulyblessed2]

This is nice. This is wonderful to use on the floor.

[AnonRNC]

We usually draw up the 0.07ml into a TB syringe and then add saline to it to make it 0.7ml total. So we don't dilute the lasix or other drug in it's original vial. We draw up only what we need from it.

This practice sounds dangerous to me. When drawing up 0.07ml, you also have a bit more medicine in the syringe tip, possibly as much as 0.05ml. So if we add saline to that syringe (vs adding that syringe to saline), we have more medicine than we have accounted for.

We have a policy for fentanyl dilution. It comes 100mcg/2ml. We draw up the 2ml, then mix with 18ml NS to equal 100mcg/20ml or 5mcg/ml. Then we draw our dose from that.

I think that it's safer to dilute first.