help...drug calculations? 500 mg ampicillin solution ordered, available solution 125mg/5mL.How much is needed?

Question

-200 g of sucrose dissolved in water to make 800 mL os solution. Whats the % strength?
-IVsolution contains 2% mannitol how many mL of solution should be given to provide pt w/ 30g of mannitol?
-2.4g of codeine in 250 mL of cough syrup. How many mL are in 1 tsp of the syrup?
-8.8 mL of water is added to 0.4 mL of a drug. What is the dilution ratio?
-You removed 95mL, 1.8L, 365 mL, and 2/5L from a container of solution. How many mL were removed in total.
-1.8 L gluclose to be administered I.V. over 12 hrs. What's the flow rate if the drop factor is 12?
-1mL of a 200 mg/mL sedative to a 150lb pt. Whats the equivalent dose in mg/kg?
-drug is supplied in tablets of 800mg strength. a 50 lb child needs a 1 week supply at a dose of 40 mg/lb every 12 hrs. How many tablets are needed in total?
-Ketamine in 100mL vial that has 100mg/mL. If 1 mL of ketamine is diluted 1:25 how many mg are in 5 mL of the diluted solution?
-1 tablet contains 75mg of a drug, how many g are in 250 tablets?

Answer 1

(1) 20mL

500mg needed. You have 125mg / 5mL

You need 500 x 5 / 125 mL = 2500/125 mL = 20mL

OR
5mL = 125mg
10mL = 250mg
20mL = 500mg <= this is what you need!

(2)
200g sucrose in 800mL sterile water is the same concentration as 200/8 or 25g in 100mL

This is a 25% solution

(3)
2% mannitol has 2g mannitol per 100mL solution

You want 30g

which is the same as 30 x 100 / 2 mL = 1500mL (or 1.5L) which is a lot ***CHECK THIS DOSAGE WITH THE DOCTOR***

(4)
2.4g codeine in 250mL
1 tsp is 5mL in metric measures
NB US teaspoon and UK teaspoon measures differ from metric teaspoon measure

(5)
0.4mL of drug in 8.8mL of water
OOoooh - dilution ratio is an old concept that I haven't been taught. Okay let me see
8.8 / 0.4 gives you 22
1:22 I think

The only tricky bit here is that I don't know if you are supposed to add the drug volume and do 9.2/0.4 which would make it 1:23

(6)
95+1800+365+400mL = 2660mL removed from the container in total

(7)
1800mL / 12hrs is 150mL/hr
You would need to know the particular volume of the drops in the giving set. I guess that's what you mean by the drop factor, but I am used to giving sets that will say: 20drops = 1mL or some such.

If 12drops = 1mL (I'm not sure if this is what you mean by drop factor) then you have 1800 drops/hr = 30 drops/min = 5 drops ever 10 sec

(8)
200mg of sedative is given to the 150lb patient (68kg). You have given a dose of 2.9mg/kg

(9)
40mg/lb every 12 hrs for a 50lb child is 2000mg 12 hrly
If you only have 800mg tablets, you will be needing to supply 2.5 tabs every 12 hrs (twice a day)

In many cases you might have to discard the extra 0.5 tablet and dispense 3 tablets twice a day for 7 days (ie 42 tablets)

In some cases you might be able to keep the extra 0.5 tablet and then you would only need to give 5 tablets each day for 7 days (35 tablets)

(10)
WOW - lots of Ketamine!
100mg/mL ... you have 1mL (= 100mg) and you dilute it 1:25 and then you draw off 5mL you should have 1/5 of your original 100mg which is to say 20mg

(11)
75mg in 1 tablet
75x250 mg in 250 tablets = 18750mg
or 18.75g in 250 tablets

Answer 2

If you can't figure these out without assistance, I do NOT want you dispensing meds.

C'mon. If there's 125 mg of ampicillin in a 5 ml dose, isn't it obvious that you need four 125 mg doses - and thus 20 ml of solution - in order to get 500 mg of ampicillin?

You can't add up 95 milliliters, 1.8 liter, 365 milliliters and 2/5 of a liter? Hint: how many milliliters are there in a liter?

Maybe you should be taking classes for hod carrying, instead?

Answer 3

Hmm, yeah if you're expected to know how to do these, the best thing is to let you work on them yourself. You should know the metric system by now, I'll bet. Struggling with it will make it stay with you longer.