Pharmacy Calculations - HELP

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Sue in Florida

69 months ago

How many mg of mag sulfate are in 3 mls of a 50% solution? Can you also show me how you get the answer for this.

Thx

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Piineeek in Lodi, New Jersey

69 months ago

well if im not mistaken 50% means that there is 50g/100ml (wt/vol calculations) so it is 50000mg in 100ml and xmg in 3ml. Do the ratio and cros multiply and you should get 1500 mg in 3 ml???

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khristine in La Quinta, California

68 months ago

30ml x 50/100 = 15gram
then convert to milligram = 15,000 mg

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hasmukh Patel in London, United Kingdom

57 months ago

nice to know that help is available online

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vampirekisses100@aol.com in Wilkes Barre, Pennsylvania

57 months ago

i need help on pharmacy tech math can not get it could you send me some easy tips ect gowing to lccc for this in naticoke pa

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brookepie in Arden, North Carolina

56 months ago

can someone help me with this calculation?

Heparin 25000 U in 250 ml D5W is running through an administration set delivering 60 drops/min. The flow rate required to deliver a heparin dose of 15U/ml is?

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Angie Guevara in Sherman Oaks, California

55 months ago

I need lots of help with calculations, it's nice to know that I can count with a lot techs out there.

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crystal in Everett, Washington

54 months ago

I always have problem converting this problem. How can I can resolve the easy way?

250mg/5ml

25mg/kg per dose (max. 1000mg per dose) twice daily for 10 days,
Weigh=23kg

Can you show me please,

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Jose in Elmhurst, Illinois

54 months ago

Crystal:

For every 1kg of weight, you add a dose of 25mg.

So if the proposed person weighs 23 kg, then you multiply 23 kg (cancel the kg) by 25 mg
(23 x 25mg) = 575mg

Then you do a cross multiplication to find out how many mL's have 575 mg, so

250mg/5mL = 575mg/XmL

Solve for x and you get 11.5mL per dose

So ultimately, the prescription would be:
Take 11.5mL by mouth twice daily for 10 days.

Going beyond, you should get [(11.5mL * 2)*10 days] = 230mL dispensed.

Any questions?

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crystal in Everett, Washington

54 months ago

Jose in Elmhurst, Illinois said: Crystal:

For every 1kg of weight, you add a dose of 25mg.

So if the proposed person weighs 23 kg, then you multiply 23 kg (cancel the kg) by 25 mg
(23 x 25mg) = 575mg

Then you do a cross multiplication to find out how many mL's have 575 mg, so

250mg/5mL = 575mg/XmL

Solve for x and you get 11.5mL per dose

So ultimately, the prescription would be:
Take 11.5mL by mouth twice daily for 10 days.

Going beyond, you should get [(11.5mL * 2)*10 days] = 230mL dispensed.

Any questions?

Yes. Is this the right dose for 23kg child? (per md request maximum 1000mg per dose)

so I would give the child 10 mls twice daily for 10 days. My pharmacist said is wrong because of the the child's weight (23kg=50.6 lbs) what are the right dosing? To equivalent to his/her weight? high dose per day.

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23derron23 in San Diego, California

54 months ago

Could anyone help me with this calculation?

The dose of gentamicin sulfate is 1.7 mg/kg. how many mls of an injectable solution containing 40mg/ml should be administered to a person weighing 220 pounds?

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khristine in Bronx, New York

54 months ago

23derron23 in San Diego, California said: Could anyone help me with this calculation?

The dose of gentamicin sulfate is 1.7 mg/kg. how many mls of an injectable solution containing 40mg/ml should be administered to a person weighing 220 pounds?

220lb/2.2lb= 100kg
1.7mg/kg x 100kg =170mg

170mg/40mg/ml =4.25ml

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23derron23 in San Diego, California

54 months ago

thank you so much i ve been stuck on that problem for forever!

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Clinical Coordinator in Los Angeles, California

54 months ago

brookepie in Arden, North Carolina said: can someone help me with this calculation?

Heparin 25000 U in 250 ml D5W is running through an administration set delivering 60 drops/min. The flow rate required to deliver a heparin dose of 15U/ml is?

I've been a Pharmacist for 34 years, but drops/min is now 3rd world medicine (60 drops/min = 60 ml/hr).
Joint committee requires: 1. all anticoagulants to be delivered in automated pumps, not gravity-fed lines. 2. No use of "U" as an abbreviation.
Commercial heparin is ALWAYS 100 units/ml The dose, written as 15U/ml is both impossible to administer and unacceptablee to any Pharmacist.

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melody in Griffin, Georgia

53 months ago

Humulin N U-100 10ml Need to give 35u sub-q everyday, what would be the quanity for a dose,the quality for a day, and the days supply?

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khristine in Bronx, New York

53 months ago

35 units/100units x 10ml = 3.5 ml

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Clinical Coordinator in LA in Pasadena, California

53 months ago

The "U-100" on any insulin means 100 units/ml, therefore 35 units is 0.35 ml. The 3.5 ml answer is a 10-fold overdose and bad for length of stay. By the way, 35 units of Regular insulin does NOT have the same biological activity as 35 units of N or NPH insulin. Onset and duration are different. Additionally, please remember only Regular, Aspart and Glulisine insulin have an indication for IV use. While there are other insulins that are solutions (Glargine, Detemir) they are not to be administered IV. Also no suspension (NPH, Lente, etc) should be given IV. If the question arises, refer to a reference. I like MICROMEDEX, but any reference will probably give same info.

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Clinical Coordinator in LA in Pasadena, California

53 months ago

Dear Crystal,
regarding your follow-up question, . . . "so I would give the child 10 mls twice daily for 10 days. My pharmacist said is wrong because of the the child's weight (23kg=50.6 lbs) what are the right dosing? To equivalent to his/her weight? high dose per day."

Question 1: What Drug? You can't pick a dose without it.
Question 2: Calculated dose was 11.5 ml, not 10 ml. It makes a difference depending upon the drug. 10 ml is 2 teaspoonsfull, ok approximation for outpatient antibiotics but not for chemo related therapy, inpatient or outpatient. We will pull back oral syringes in cases in a hospital where the Pharmacist determines that accuracy is important. Always label oral syringes "FOR ORAL USE ONLY". I've actually seen a RN try to give oral Risperdal solution IVP. When a needle would not fix on the oral syringe, she:
a. cursed the Pharmacy
b. Pulled the dose from the oral syringe into a syringe for injection and administered the brilliant blue liquid, almost 5 ml, IV Push. "If the needle don't fit, you must acquit.", or at least ask why.
-Patient was fine

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ivonne in El Paso, Texas

50 months ago

A Physician orders AMINOPHYLLIN 5mg/kg/hr in 50 ml of fluids for a patient with asthma. The patient weighs 122 lb. How many milligrams of the medication should the patient receive? Can you also show me how to get the answer for this?

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John in West Chester, Pennsylvania

50 months ago

122 lb./2.2=55.4

Round that to 55 kg

55 x 5= 275

275 mg per dose

(5mg/kg/hr)

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kc13ramirez in Hammond, Indiana

50 months ago

How many ml of a 50% MgSO4 solution do you need to put 5.5gm in an IV bag?

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regodfrey in Arlington, Texas

50 months ago

kc13ramirez in Hammond, Indiana said: How many ml of a 50% MgSO4 solution do you need to put 5.5gm in an IV bag?

50g 5.5g
--- = ---
100mL X

cross multiply to solve for X.
100(5.5) = 550
50(X) = 50x
solve for X
550/50 = 11 You would need 11mL for 5.5g

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cpht in Plainfield, Illinois

49 months ago

visit pharmacy rx by crystal zamudio for pharmacy calculations and much more

thanks :D

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sharon.roberts39 in Atlanta, Georgia

48 months ago

A doctor order 1.5 gm IV and on hand is 500 mg vials, how much medication need to be administer?

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sharon.roberts39 in Atlanta, Georgia

48 months ago

a doctor order 1.5 gm IV adn on hand is 500 mg vials, how much need to be adminster?

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Clinical Coordinator in LA in Los Angeles, California

48 months ago

First, keep your units constant. Dr wants 1.5gm. That's 1,500 mg
You have 500 mg vials. So 1,500 gm X (1 vial/500mg) = 3 vials,
Check: 500mg/vial X 3 vials = 1,500 mg

Always take a few seconds and check your work. It's unfair, but we live (work) in an environment that permits no errors.

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Clinical Coordinator in LA in Los Angeles, California

48 months ago

As I said, No errors allowed, and I made an error. It should be: 'So 1,500 MG X (1 vial/500mg) = 3 vials,

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Cpht_01 in bolingbrook, Illinois

48 months ago

here is my example

IF 500mg= 1 vial
Then 1.5gm= X .......1.5 X 1 / 500 = 0.003

we need to convert 0.003 in mg

0.003 X 1000 = 3

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vince54 in Jacksonville, North Carolina

48 months ago

sharon.roberts39 in Atlanta, Georgia said: A doctor order 1.5 gm IV and on hand is 500 mg vials, how much medication need to be administer?

0.3gm or 300mf

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efutrell in Evansville, Indiana

45 months ago

Does anyone have any helpful hints or websites for me. I am having trouble with the prescription calculations. i know how to do the math its just picking the numbers out and putting them where they need to b. thank u

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CPhT in Plainfield, Illinois

45 months ago

efutrell in Evansville, Indiana said: Does anyone have any helpful hints or websites for me. I am having trouble with the prescription calculations. i know how to do the math its just picking the numbers out and putting them where they need to b. thank u

You can visit (google)Pharmacy Rx by Crystal Zamudio

There is helpful math calculations step by step

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Ashelim in Dekalb, Illinois

45 months ago

if your given the pediatric dose, or 25mg/kg/day q8h. but your patient is 4 weeks old and weighs 8.7lbs. which is the best dose? and how do you figure?

15mg
25mg
33mg
45mg

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CPhT in Plainfield, Illinois

45 months ago

Ashelim in Dekalb, Illinois said: if your given the pediatric dose, or 25mg/kg/day q8h. but your patient is 4 weeks old and weighs 8.7lbs. which is the best dose? and how do you figure?

15mg
25mg
33mg
45mg

Your answer would be 33mg.

You have to figure out how many kilograms is 8.7lbs in order to solve the problem with the same measurements just to be equally.

8.7lbs / 2.2kg= 3.95
Every 8 hours is how many doses a day: 24 / 8= 3 doses a day

Now put it altogether: 25mg (recommended dose) X 3.95 / 3= 32.9 round and you get 33

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Ashelim in Dekalb, Illinois

45 months ago

thank you, i was not dividing my the 3 doses per day.

how about this one:
what percent strength of clemastine fumarate syrup 0.5mg/5ml?
i keep getting 10... not matter how i do it...

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Ashelim in Dekalb, Illinois

45 months ago

#1) 50% w/w contains how many grams of active ingredient per 100 grams?

#2) how do i find the highest concentration?
4mg/ml
4%
2mg/ml
2%

im just learning and cant seem to figure out certain things with the materials given to me.

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CPhT in Plainfield, Illinois

45 months ago

Ashelim in Dekalb, Illinois said: thank you, i was not dividing my the 3 doses per day.

how about this one:
what percent strength of clemastine fumarate syrup 0.5mg/5ml?
i keep getting 10... not matter how i do it...

anything that is a % is always 100

If 0.5mg = 5ml
Then X = 100 ---------0.5 X 100 / 5 = 10

so that is 10 mg, but the question is asking for a percent strength
so we have to change 10 to a percent..here is how below

first we start off with changing 10 to a decimal and then we can change it to a %

10 / 100 = 0.1
0.1 X 100 = 10%

So basically I am getting ten percent as well.

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CPhT in Plainfield, Illinois

45 months ago

Ashelim in Dekalb, Illinois said: #1) 50% w/w contains how many grams of active ingredient per 100 grams?

#2) how do i find the highest concentration?
4mg/ml
4%
2mg/ml
2%

im just learning and cant seem to figure out certain things with the materials given to me.

1) If 50g = 100g
Then X = 100g ----- 50 X 100 / 100= 50g of active ingredient

2)I think 4mg/ml is the highest concentration..why?
well there are 4mg in 1ml
4% would be 0.04ml, which I do not think it is alot
I cancelled out the 2%, 2mg/ml because we all know 4 is higher than 2.

You can visit my site for any homework help if you like. <google> Pharmacy Rx by Crystal Zamudio

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Ashelim in Dekalb, Illinois

45 months ago

thank you so much. it really helps~
alligations:

how much 1:25 solution and 1:500 solution should you mix to make a 1L of a 1:250 soaking solution?

i cannot get matching answers...

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Ashelim in Dekalb, Illinois

45 months ago

:/
how many grams of 0.1% cream should you mix with 12g of 12% cream to make a 6% cream?

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CPhT in Joliet, Illinois

45 months ago

Ashelim in Dekalb, Illinois said: thank you so much. it really helps~
alligations:

how much 1:25 solution and 1:500 solution should you mix to make a 1L of a 1:250 soaking solution?

i cannot get matching answers...

lets convert the ratios into a percent in order to solve the problem with the alligation method

1:25 (1 / 5= 4%) 1:500 (1 / 500= 0.2%) 1:250 (1 / 250= 0.4%)
1 liter = 1000ml

now lets do the tic tac toe

_4%____l__________l___0.2%_ / 3.8% X 1000ml= 53ml

l 0.4% l 3.8%
____________________________

0.2% l l 3.6% / 3.8% X 1000ml= 947ml

*The desired % goes in the middle(0.4%), the higher % goes to the left top corner(4%), the lower % goes to the left bottom corner (0.2%).

*Now 0.2% - 0.4%= 0.2% (the 0.2% goes on the right top corner) / Now 4% - 0.4%= 3.6% (the 3.6% goes to the right bottom corner)

*You add both 0.2% + 3.6%= 3.8% (the 3.8% goes in the right middle box)

*Now you do math as I shown on the very top page next to the tic tac toe.

*To know if your problem was correct, simply add both final % and it will equal to the Milliliter given in the problem

53 plus 947= 1000ml

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CPhT in Joliet, Illinois

45 months ago

can you provide your email Ashelim because when I try to make a tic tac toe it looks weird as you can see above ..so I will email you the answer to get a better view ok

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CPhT in Joliet, Illinois

45 months ago

Ashelim in Dekalb, Illinois said: how much NaCl 10% stock solution should you add to 100ml of NaCl 0.45% solution to make normal saline?

there is no final volume, so im not sure how to plug it in...

sorry to keep bothering you

this is an alligation problem as well.

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CPhT in Joliet, Illinois

45 months ago

Ashelim in Dekalb, Illinois said: you have a stock vial of cefotaxime 500mg/10ml. the dose is 2g over 30 minutes. what is the flow rate in ml/hr

So lets find out how many milliliters is in 2g
before we find out the ml we have to convert 2g into mg..remember we have to calculate with the same equal measurements to have a fair answer. Also the question is asking ml/hr..the question provides 30 minutes so we have to convert it to hours (30min / 60= 0.5hrs)

If 1g = 1000mg
Then 2g = X -------2 X 1000 / 1= 2000mg

Now lets find out how many ml is in 2000mg

If 500mg = 10ml
Then 2000mg = X ----------2000 X 10 / 500= 40ml

Now lets plug the answer in a flowrate formula
FORMULA: V(volume)
_________
T(time) x C (calibration)= R (rate of flow rate)

40ml
____
0.5hrs = flowrate of 80ml/hr

<this question does not provide calibration so we just divide>

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CPhT in Joliet, Illinois

45 months ago

again sorry it seems I can't type formulas because it keeps looking weird..I will provide the flowrate answer again via email..it will look better..

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Brandon Kirchoff in Charlotte, North Carolina

45 months ago

Are there any good free online guides for calculations? I did a bunch of practice tests at www.medpreps.com, which were helpful, but I could use a good study guide.

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Haley in Dekalb, Illinois

45 months ago

A prescription is written for Humulin N U-100 Insulin, 10mL, 40 units daily. What is the days supply?

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Ashelim in Dekalb, Illinois

45 months ago

i cant seem to figure this one out either... you have a stock vial of product 30mg/ml. how many ml will you need to prepare an iv infusion containing a dose of 150mg/50 ml.
the only way i can figure... i get 10. can you explain how to set this up?

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CPhT in Joliet, Illinois

45 months ago

Haley in Dekalb, Illinois said: A prescription is written for Humulin N U-100 Insulin, 10mL, 40 units daily. What is the days supply?

Insulin : 1ml = 100 units

sig says you have 10ml so.... 10 X 100= 1000 units
Doctor wants patient to take 40 units a day (daily) so
1000 / 40= 25 days (day supply)

Crystal Zamudio
Pharmacy Rx Owner

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CPhT in Joliet, Illinois

45 months ago

Ashelim in Dekalb, Illinois said: i cant seem to figure this one out either... you have a stock vial of product 30mg/ml. how many ml will you need to prepare an iv infusion containing a dose of 150mg/50 ml.
the only way i can figure... i get 10. can you explain how to set this up?

If 150mg = 50ml
Then 30mg = X ---------- 30 X 50 / 150= 10ml

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Heather in Bolingbrook, Illinois

45 months ago

I am at a loss for the formula method to calculate this question;
The volume in ml, of cherry syrup needed to dilute 100 ml of Phenobarbital 20 mg/5 ml to a concentration of 2 mg/ml is

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