Help With Calculation of Dosages

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help you are instructed to give cephalexin monohydrate [keflex] 05g the drug comes as 250mg per capsule how many capsule would you give. could someone help me set this calculation up, thank you.

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I assume you mean 0.5g. This decimal is very important so make sure you are accurate in providing decimals. Ok so here goes the problem.

The order reads:give 0.5g you place this in the problem first:

0.5g | | | | capsule

-------------------------------------------------------

| | | |

then you add how it is supplied:

0.5g | 1 capsule | | | capsule

-------------------------------------------------------

| 250mg | | |

Now you need to convert g to mg:

0.5g | 1 capsule | 1000mg | | capsule

-------------------------------------------------------

| 250mg | 1g | |

cross off and eliminate which leaves you with:

0.5g | 1 capsule | 1000mg | 500 | 2 capsule

-------------------------------------------------------

| 250mg | 1g | 250 |

This eliminates grams, and milligrams and results in capsules. So multiply across and divide. 500 divided by 250 = 2 so 2 capsules (Sorry I couldn't do overstrikes but I hope you can visualize the crossing off.)

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I have to apologize, when I set it up and posted the problem it changed the way it was laid out. If you can't understand it (and it is confusing shown this way) let me know and I will re explain it in words. But for the most part, figure out what you are ordered, 0.5g. How it is supplied 250mg per capsule. convert g to mg so you can get rid of the grams and mg and are left only with capsules. Multiply across, divide the results and it leaves you with 2 capsules. Always start with what is ordered, then fill in what you want (capsules in this case) and then add how it is supplied. Add accordingly to convert and cross off unwanted items (g and mg). leaves you only with capsules. Then do the math to get the answer. Hope that helps.

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I assume you mean 0.5g. This decimal is very important so make sure you are accurate in providing decimals. Ok so here goes the problem.

The order reads:give 0.5g you place this in the problem first:

0.5g | | | | capsule

-------------------------------------------------------

| | | |

then you add how it is supplied:

0.5g | 1 capsule | | | capsule

-------------------------------------------------------

| 250mg | | |

Now you need to convert g to mg:

0.5g | 1 capsule | 1000mg | | capsule

-------------------------------------------------------

| 250mg | 1g | |

cross off and eliminate which leaves you with:

0.5g | 1 capsule | 1000mg | 500 | 2 capsule

-------------------------------------------------------

| 250mg | 1g | 250 |

This eliminates grams, and milligrams and results in capsules. So multiply across and divide. 500 divided by 250 = 2 so 2 capsules (Sorry I couldn't do overstrikes but I hope you can visualize the crossing off.)

Thank you, could you help me with three more calculation I would appreciate that very much. anyone.

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Specializes in Emergency.
Thank you, could you help me with three more calculation I would appreciate that very much. anyone.

Now that Jo'ee explained how to set up the equation, show us what you come up with on those questions and we'll help you from there.

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you are instructed to give penicillin v potassium [pen k suspension] 0.75g The drug is available as250mg per 5ml how many milliliters would you give?

If the client is to receive insulin at 3 units/hr with solution of 50 units per 100 ml in normal saline [NS]the rate of infusion in milliliters would be.?

3 You are instructed to give cyclophosphamide [Cytoxin 4 mg /kg per day PO the client weight 154lb how much cytoxan would you give each day?

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Now that Jo'ee explained how to set up the equation, show us what you come up with on those questions and we'll help you from there.

D/H x Q 0.75/250= 0.003X5=15 ml

D/H X Q 154 X2.2 = 338/4=

That's why I'm asking you good people for help I'm stuck. I think I am doing the formulas wrong,

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Specializes in Emergency.
D/H x Q 0.75/250= 0.003X5=15 ml

D/H X Q 154 X2.2 = 338/4=

That's why I'm asking you good people for help I'm stuck. I think I am doing the formulas wrong,

You got #1 correct.

2) If the client is to receive insulin at 3 units/hr with solution of 50 units per 100 ml in normal saline [NS]the rate of infusion in milliliters would be.?

100ml/50units x 3 units/1hr = ?

3) You are instructed to give cyclophosphamide [Cytoxin 4 mg /kg per day PO the client weight 154lb how much cytoxan would you give each day?

4mg/1kg x 1kg/2.2lbs x 154lbs/1 = ?

I always start with whatever unit I want the answer to be. #2 wants the answer as milliliters so I started with whatever info the question gave me in ml (50units per 100ml). #3 wanted milligrams so I started with 4mg /kg. I'll post up the answers after I've given your brain a thorough workout :D

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An easier way to do the penicillin equation would be to convert the 0.75g into milligrams (since it's already a decimal, it will be made into a whole number.. so much easier to convert). I learned this the hard way after 20 calculations and driving myself nuts!! need 750mg .. available as 250mg/5ml. 750/250= 3; 3 x 5mL= 15mL

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You got #1 correct.

2) If the client is to receive insulin at 3 units/hr with solution of 50 units per 100 ml in normal saline [NS]the rate of infusion in milliliters would be.?

100ml/50units x 3 units/1hr = ?

3) You are instructed to give cyclophosphamide [Cytoxin 4 mg /kg per day PO the client weight 154lb how much cytoxan would you give each day?

4mg/1kg x 1kg/2.2lbs x 154lbs/1 = ?

I always start with whatever unit I want the answer to be. #2 wants the answer as milliliters so I started with whatever info the question gave me in ml (50units per 100ml). #3 wanted milligrams so I started with 4mg /kg. I'll post up the answers after I've given your brain a thorough workout :D

Thanks...:redbeathe:redbeathe:redbeathe

Up Vote Up Vote ×
An easier way to do the penicillin equation would be to convert the 0.75g into milligrams (since it's already a decimal, it will be made into a whole number.. so much easier to convert). I learned this the hard way after 20 calculations and driving myself nuts!! need 750mg .. available as 250mg/5ml. 750/250= 3; 3 x 5mL= 15mL

Thanks:redbeathe:redbeathe:redbeathe

Up Vote Up Vote ×
I assume you mean 0.5g. This decimal is very important so make sure you are accurate in providing decimals. Ok so here goes the problem.

The order reads:give 0.5g you place this in the problem first:

0.5g | | | | capsule

-------------------------------------------------------

| | | |

then you add how it is supplied:

0.5g | 1 capsule | | | capsule

-------------------------------------------------------

| 250mg | | |

Now you need to convert g to mg:

0.5g | 1 capsule | 1000mg | | capsule

-------------------------------------------------------

| 250mg | 1g | |

cross off and eliminate which leaves you with:

0.5g | 1 capsule | 1000mg | 500 | 2 capsule

-------------------------------------------------------

| 250mg | 1g | 250 |

This eliminates grams, and milligrams and results in capsules. So multiply across and divide. 500 divided by 250 = 2 so 2 capsules (Sorry I couldn't do overstrikes but I hope you can visualize the crossing off.)

Thanks..:redbeathe:redbeathe:redbeathe:redbeathe

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