Pharmacy Calculations - HELP

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CPhT in Joliet, Illinois

44 months ago

Heather in Bolingbrook, Illinois said: 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

Is that the exact question given. Something tells me a part of information is missing but if that is the question I will try my best to help you. Hey I'm from bolingbrook too.

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Heather in Bolingbrook, Illinois

44 months ago

CPhT in Joliet, Illinois said: Is that the exact question given. Something tells me a part of information is missing but if that is the question I will try my best to help you. Hey I'm from bolingbrook too.

Yes, it actually is the full question. It is a practice exam question straight from the PTCB exam. I paid 30.00 to take the practice exam.
Cool you are from the Brook too.

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CPhT Online in Tempe, Arizona

44 months ago

First convert 20mg/5mL to mg per mL. 20mg/5mL = 4mg/mL.

Now, you want to get to 2mg/mL which is half as concentrated of what you have. Use the dilution formula below:

concentration(start) * volume = concentration(end) * volume(end)

4mg * 100mL = 2mg * XmL
400 = 2 * XmL
400/2 = 200
X = 200mL

You need to dilute to 200mL, so add 100mL of cherry syrup.

To explain in words:

If you start with 100mL at 4mg/ml you have 400mg of phenobarbital in 100mL. If you dilute with another 100mL of syrup, you will still have 400mg of phenobarbital, but now in 200mL. Then divide 400mg/200mL = 2mg/ml.

If you need more help, there is a calculations practice exam at cphtonline.com/practice-exam.html.

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CPhT in Joliet, Illinois

44 months ago

Here is a similar formula that works as well
Concentration and dilution formula:

C1 X V1 divide C2 or V2

C= concentration (mg)
V= volume (ml)

4mg X 100ml / 2mg = 200ml

400mg / 200ml = 2mg/ml

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CPhT in Joliet, Illinois

44 months ago

Heather in Bolingbrook, Illinois said: 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

Here is another way as well

20mg = 5ml
X = 100ml ------- 20 X 100 / 5= 400mg

2mg = 1ml
400mg = X --------- 400 X 1 / 2 = 200ml

400mg / 200ml = 2mg/ml

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Ashelim in Dekalb, Illinois

44 months ago

Neogestimine is available in a 1:1000 concentration in a 20ml vial. You have a perscription for 16mg. how many ml are required.

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Ashelim in Dekalb, Illinois

44 months ago

Neostigmine*

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CPhT in Crest Hill, Illinois

44 months ago

Ashelim in Dekalb, Illinois said: Neogestimine is available in a 1:1000 concentration in a 20ml vial. You have a perscription for 16mg. how many ml are required.

So there is 1 gram per 1000ml (1:1000) in a 20ml vial..the doctor is prescribing 16mg from a 20ml vial..the question is asking how many ml would you give from a 16mg....

before solving our problem we need to convert 16mg to grams since the vial concentration comes in g per ml
16 / 1000= 0.016 grams

If 1 g = 1000ml
Then 0.016 g = X --------0.016 x 1000 / 1= 16 ml

you will need 16ml from a 20ml vial....

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CPhT in Crest Hill, Illinois

44 months ago

Ashelim in Dekalb, Illinois said: Neogestimine is available in a 1:1000 concentration in a 20ml vial. You have a perscription for 16mg. how many ml are required.

So there is 1 gram per 1000ml (1:1000) in a 20ml vial..the doctor is prescribing 16mg from a 20ml vial..the question is asking how many ml would you give from a 16mg....

before solving our problem we need to convert 16mg to grams since the vial concentration comes in g per ml
16 / 1000= 0.016 grams

If 1 g = 1000ml
Then 0.016 g = X --------0.016 x 1000 / 1= 16 ml

you will need 16ml from a 20ml vial....

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Mamarosa in Toronto, Ontario

44 months ago

I need help how to figure this

Dilaudid HP 10mg/ml Cassette Available 10mg/ml
a) To make a 100ml cassette, how many mg's of Dilaudid HP is it?
b) Running at 2ml/hr how long will 1 cassette last?
c) 28ml TBA at 9am the next cassette is due when?

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CPhT in Lockport, Illinois

44 months ago

Mamarosa in Toronto, Ontario said: I need help how to figure this

Dilaudid HP 10mg/ml Cassette Available 10mg/ml
a) To make a 100ml cassette, how many mg's of Dilaudid HP is it?
b) Running at 2ml/hr how long will 1 cassette last?
c) 28ml TBA at 9am the next cassette is due when?

A.) 10mg = 1 ml
X = 100 ml ----10 X 100 / 1 = 1000mg

B.)2 ml = 1 hr
100ml = X ---------- 100 X 1 / 2 = 50 hours
[50 hours is 2 1/2 days]

C.)
10mg = 1ml
X = 28ml --------10 X 28 / 1 = 280mg

2mg = 1 hr
280mg = X ----- 280 X 1 / 2 = 140 hours [5 1/2 days]

Pharmacy Rx Owner

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Clinical Coordinator in Los Angeles, California

43 months ago

Where 100 ml lasts for 50 hrs @ 2ml/hr, 28 ml should last 14 hrs at same rate not 140 hrs. There is no purpose in changing ml to mg in that case. Just goes to show you, always get a second look, or check, on patient isssues to avoid embarrasing or deadly mistakees.

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CPhT in Lockport, Illinois

43 months ago

CPhT in Lockport, Illinois said: A.) 10mg = 1 ml
X = 100 ml ----10 X 100 / 1 = 1000mg

B.)2 ml = 1 hr
100ml = X ---------- 100 X 1 / 2 = 50 hours
[50 hours is 2 1/2 days]

C.)
10mg = 1ml
X = 28ml --------10 X 28 / 1 = 280mg

2mg = 1 hr
280mg = X ----- 280 X 1 / 2 = 140 hours [5 1/2 days]

Pharmacy Rx Owner

Oh shoot! Sorry Here is letter C.) correction
100ml = 50 hours
28ml = X --------28 X 50 / 100 = 14 hours

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jimmy in San Antonio, Texas

43 months ago

dr orders gentamicin 3mg/k a day. the patient weighs 70 lb ,we have available gentamicin 80mg/2ml vial. how many mls woul the patient recieve?

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jimmy in San Antonio, Texas

43 months ago

dr orders gentamicin 3mg/k a day the patient weighs 70 lb we have available gentamicin 80mg/2ml vial how many mls would the patient receive?

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CPhT in Joliet, Illinois

43 months ago

jimmy in San Antonio, Texas said: dr orders gentamicin 3mg/k a day the patient weighs 70 lb we have available gentamicin 80mg/2ml vial how many mls would the patient receive?

70lbs / 2.2 = 31.8 or 32k

3mg = 1 k
X = 32 k ----------< 3 x 32 / 1 = 96 mg

80mg = 2ml
96mg = X ----------< 96 x 2 / 80 = 2.4 ml the patient will receive

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jimmy in San Antonio, Texas

43 months ago

thanks for the help really apreciated

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John in Milledgeville, Georgia

43 months ago

How many grams of 20% benzocaine ointment and how many grams of ointment base (diluent) should be used in preparing 5lb of 2.5% benzocaine ointment?

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John in Milledgeville, Georgia

43 months ago

How many grams of 20% benzocaine ointment and how many grams of ointment base (diluent) should be used in preparing 5lbs of 2.5% benzocaine ointment?

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amber in Tracy, California

43 months ago

Can I get a really easy way to understand initial strength..initial volume...final strength ...final volume HELP!!!!

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CPhT in Plainfield, Illinois

43 months ago

amber in Tracy, California said: Can I get a really easy way to understand initial strength..initial volume...final strength ...final volume HELP!!!!

You can Google [Pharmacy Rx by Crystal Zamudio] click math link and scroll down.

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CPhT in Plainfield, Illinois

43 months ago

John in Milledgeville, Georgia said: How many grams of 20% benzocaine ointment and how many grams of ointment base (diluent) should be used in preparing 5lbs of 2.5% benzocaine ointment?

do have a email so I can email you the math answer, for some reason the forum wont let me post my answer. weird huh..this is what the forum is saying below.

[We do not allow vulgar language, personal attacks, or phone numbers in our forums. Please edit your comment appropriately.]

I did not use any of those so please provide your email if you can or google my site [pharmacy rx] to contact me..thanks
FYI: my answer was 284g of 20% benzocaine oint
& 1984g of ointment base

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Shannon in Shalimar, Florida

42 months ago

Can someone show me how to solve this equation, please? How many ml of a 20% solution should be added to 50 ml of a 40% solution to obtain a 24% solution? Thank you in advance.

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Shannon in Shalimar, Florida

42 months ago

Can someone please help me solve this one and please show how you got the answer?
How many ml of a 20% solution should be added to 50 ml of a 40% solution to obtain a 25% solution?

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Cpht_01 in bolingbrook, Illinois

42 months ago

Shannon

25% is the final solution that is needed to obtain.
40% parts (-) 25% parts = 15 parts
20% parts (-) 25% parts = 5 parts
15% parts + 5% parts = 20% parts

5% parts x 50ml / 20% parts = 12.5 ml
15% parts x 50ml / 20% parts = 37.5ml

Your answer is: You need 37.5ml of a 20% sol to obtain a 25% sol

Tip: Add both final ml (12.5ml + 37.5ml = 50ml). As you can see both final ml equal to the 50ml in the question, so this a way to see if your answer was correct. This is an alligation math problem and it is often solved with a tic tac toe table..I can show you via email because the forum would not allow me to properly explain...You can click my profile name on the left to get access to my email.

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Cpht_01 in bolingbrook, Illinois

42 months ago

Shannon in Shalimar, Florida said: Can someone please help me solve this one and please show how you got the answer?
How many ml of a 20% solution should be added to 50 ml of a 40% solution to obtain a 25% solution?

Shannon

25% is the final solution that is needed to obtain.
40% parts (-) 25% parts = 15 parts
20% parts (-) 25% parts = 5 parts
15% parts + 5% parts = 20% parts

5% parts x 50ml / 20% parts = 12.5 ml
15% parts x 50ml / 20% parts = 37.5ml

Your answer is: You need 37.5ml of a 20% sol to obtain a 25% sol

Tip: Add both final ml (12.5ml + 37.5ml = 50ml). As you can see both final ml equal to the 50ml in the question, so this a way to see if your answer was correct. This is an alligation math problem and it is often solved with a tic tac toe table..I can show you via email because the forum would not allow me to properly explain...You can click my profile name on the left to get access to my email.

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lalala in West Covina, California

42 months ago

Shannon in Shalimar, Florida said: Can someone please help me solve this one and please show how you got the answer?
How many ml of a 20% solution should be added to 50 ml of a 40% solution to obtain a 25% solution?

x is the volume of 20% solution in mL
50 is the volume of 40% solution
(x+50) is the total volume of the resulting 25% solution

0.2x + 0.4(50) = 0.25(x+50)
0.2x + 20 = 0.25x + 12.5
7.5 = 0.05x
x = 150 mL

so 150mL of 20% solution and 50mL of 40% solution will give you 200mL of 25% solution

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lalala in West Covina, California

42 months ago

Cpht_01 in bolingbrook, Illinois said: Shannon

25% is the final solution that is needed to obtain.
40% parts (-) 25% parts = 15 parts
20% parts (-) 25% parts = 5 parts
15% parts + 5% parts = 20% parts

5% parts x 50ml / 20% parts = 12.5 ml
15% parts x 50ml / 20% parts = 37.5ml

Your answer is: You need 37.5ml of a 20% sol to obtain a 25% sol

Tip: Add both final ml (12.5ml + 37.5ml = 50ml). As you can see both final ml equal to the 50ml in the question, so this a way to see if your answer was correct. This is an alligation math problem and it is often solved with a tic tac toe table..I can show you via email because the forum would not allow me to properly explain...You can click my profile name on the left to get access to my email.

the final volume isn't 50mL

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lalala in West Covina, California

42 months ago

if the resulting solution was to be 50mL, you can use system of equations

x is the volume of 20% solution in mL
y is the volume of 40% solution in mL
50 is the final volume of 25% solution

your two equations
0.2x + 0.4y = 0.25(50)
x + y = 50

rewrite second equation and plug in to the first
y = 50 - x

0.2x + 0.4(50-x) = 0.25(50)
0.2x + 20 - 0.4x = 12.5
-0.2x = -7.5
x = 37.5
then y = 12.5

i don't know your preference, but i prefer sticking to algebraic methods because i don't fully understand alligations.

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Shannon in Shalimar, Florida

42 months ago

Thank you for helping me with my equation. I knew it was not an alligation when my answers did not match with the choices that I had. I have been stumped by this only question for 3 days. Thank you for helping me once again in solving this equation.

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Cpht_01 in bolingbrook, Illinois

42 months ago

Sorry Misunderstood
(Here is my version)

20%X + 40%(50ml) = 25% (x+50ml)
20%X + 2000 = 25% (x+50ml)

Divide 20 both sides to isolate X

(20%X / 20) (2000 / 20= 100ml)

Put it altogether
25% (100ml + 50ml)-----solve equation 100 + 50ml = 150ml

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asatta in Indianapolis, Indiana

42 months ago

Sue in Florida said: 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

can you show me how to do order over supply?

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Mabry in Fayetteville, North Carolina

38 months ago

I've been stuck on this forever, can someone please help me with usual and customary prices. The question says calcualte the retail price of the following prescrpition using the formula AWP+professional fee=retail price of prescription if the professional fee is determined using the chart in the example below:

AWP Professional Fee
less than $20.00 $4.00
$20.01-$50.00 $5.00
$50.01 and more $6.00

1. Verapamil SR Tabs #30 AWP/100 $135.85 Retail price___________

When I worked it out I got $141.85 then I looked in the back of the book and the answer was $45.76. My question is how the heck did they get $45.76?!?!?!

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Mabry in Fayetteville, North Carolina

38 months ago

I've been stuck on this forever, can someone please help me with usual and customary prices. The question says calcualte the retail price of the following prescrpition using the formula AWP+professional fee=retail price of prescription if the professional fee is determined using the chart in the example below:

AWP / Professional Fee
less than $20.00 / $4.00
$20.01-$50.00 / $5.00
$50.01 and more / $6.00

*NOTE: Sorry I don't know why the chart posted liked that but The Average Wholesale Price is to the left and the Professional fee if to the right. As in if the AWP is less than $20.00 the professional fee would be $4.00. If the AWP is $20.01 - $50.00 the professional fee would be $5.00, and if the AWP is $50.01 and more then the professional fee would be $6.00.

1. Verapamil SR Tabs #30 AWP/100 $135.85 Retail price___________

When I worked it out I got $141.85 then I looked in the back of the book and the answer was $45.76. My question is how the heck did they get $45.76?!?!?!

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Mai C. in Walnut Creek, California

37 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?

There are 100units in a 10ml vial of Humulin-N
100units x 10ml = 1,000units
1,000units / 40units = 25
The answer: 25 days supply

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Sami in Allen, Texas

36 months ago

Mabry in Fayetteville, North Carolina said: I've been stuck on this forever, can someone please help me with usual and customary prices. The question says calcualte the retail price of the following prescrpition using the formula AWP+professional fee=retail price of prescription if the professional fee is determined using the chart in the example below:

AWP / Professional Fee
less than $20.00 / $4.00
$20.01-$50.00 / $5.00
$50.01 and more / $6.00

*NOTE: Sorry I don't know why the chart posted liked that but The Average Wholesale Price is to the left and the Professional fee if to the right. As in if the AWP is less than $20.00 the professional fee would be $4.00. If the AWP is $20.01 - $50.00 the professional fee would be $5.00, and if the AWP is $50.01 and more then the professional fee would be $6.00.

1. Verapamil SR Tabs #30 AWP/100 $135.85 Retail price___________

When I worked it out I got $141.85 then I looked in the back of the book and the answer was $45.76. My question is how the heck did they get $45.76?!?!?!

You have to divide 30 by 100 because the formula applies for every 100 tablets. So you take 100 and divide it by 30 to get 3.3333 and so on. You then divide that by $135.85 to get $45.76.

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justin in San Ramon, California

34 months ago

my patient is using Duragesic 100 mcg topically every 3 days and her MD wants to change her patch medication to oral medication . She also takes 2 doses of roxanol 20 mg a day . What dose of MS contin would you recommend ?

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justin in San Ramon, California

34 months ago

Mr Wallace is currently taking MS contin 45 mg PO bid . Calculate the breaktthrough dose of roxanol using the 10% rule and document the order you would expect to see from the physician;

Over the last few days , Mr Wallace has been taking 6 doses of roxanol in a 24 hour period . You would recommend increasing his MS Contin to _______.

You would recommend increasing Mr. Wallace's roxanol for breakthrough pain to _________.

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Calyn Brown in Chicago

34 months ago

Pharmacy technician performs pharmacy related functions and generally works under the supervision of a licensed pharmacist or other health professional. Pharmacy technicians work in a variety of locations, usually in hospital pharmacies but also sometimes in pharmaceutical manufacturers, insurance companies, computer software companies, or in government or teaching. Following site has the details information about this career-it's scope and job opportunities.
www.bls.gov/oco/ocos325.htm

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aana in Delhi, India

34 months ago

The amount of glucose required to make a solution for intravenous injection containing 0.18% w/v of sodium chloride solution iso-osmotic with blood sereum is
a)3.4
b)5.0
c)4.2
d)2.4

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Dave in Surprise, Arizona

33 months ago

I'm using mosby's i'm in chapt 4 in the workbook. under conv prob 6 they have B\x/= blank%. nowhere in this chapter do they cover this type of calculation. Help!!!

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paivir in Dumfries, United Kingdom

33 months ago

I cannot get this solved using two different formulas, keep getting one of them wrong...

I have 25mg/5ml solution of codeine linctus and I want to make 500ml of codeine linctus 15mg/5ml. How much of the concentrated solution do I need??

Must have been trying too hard, mind all boggled now... Thanks!

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kenerson2010 in Redding, California

32 months ago

i am currently taking online classes for pharmacy tech, but i am stuck on the calculations part. does anyone know of a website or book that can help me with it that is really easy to understand?

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ham-on in Hendersonville, Tennessee

30 months ago

crystal in Everett, Washington said: 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.

First off, there is a difference between milligrams and milliliters. Milligrams is a measure of weight, while milliliters is a measure of volume. Milligrams refers to the weight of the drug being administered, while milliliters refers to the volume of the end solution (or mix). The question states that the amount of drug dosage cannot exceed 1000mg. It does not, it is only a dose of 575mg. Plus, 1000mg=1g=1ml, so your statement is flawed stating, "I would give the child 10 mls twice daily for 10 days." If you truly thought 1000mg were the limit, you would have stated you would give the child 1 mls twice daily for 10 days.

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wiam in Austin, Texas

29 months ago

Sue in Florida said: 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

1500mg
50 100
x 3ml
x=1.5gm
1.5*1000=1500mg

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Danna in Mercer Island, Washington

28 months ago

I am stuck on these 2 problems, and the formulas that I am using I don't believe are working to find the correct answer.

Problem #1
You have 4 oz of a 50% solution. If 500 mL was added to the 50% solution what is the percentage strength of the new solution?

Problem #2
If 14 grams of petrolatum is added to 25 grams of 0.2% hydrocortisone ointment, what will be the final percent concentration of the hydrocortisone?

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prince07 in Oakland, California

28 months ago

Can you translated this prescription and show the calculations.plz

Prozac 10mg #100,sig :20 mg PO qam

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wiam in Austin, Texas

28 months ago

prozac 10mg (either cap or tab.)the no.(#) is 100
patient must take 20mg(2tablets)by mouth(po)every morning(qam)it is better to take it at the same time every morning(this means that if the patient took the dose on 8 am in the morning so he/she must take all the other doses on 8am every day.

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wiam in Austin, Texas

28 months ago

prazac 10mg #(no.)is 100 whether tablets or capsules,sig(direction for use)is 20 mg (2tablets of 10 mg strength) po(by mouth)every morning(qam)it is better that the patient will take the dose in the same time every morning e.g if he/she took the 1st dose on 8am so the next dose must be on 8am and so on

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Catalina Q in Beaverton, Oregon

28 months ago

It would be #2 10mg tablets to equal 20mg. to be given every morning. you would dispence the exact amount 100 tablets. Which look like a 50 day supply. So the lable would say.

Take 2 tablets by mouth every morning.

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