[vinayaraj]

how do we prepare antibiotic stock solution whose potency is given in units per mg..is it the same way for microgram per mg?pls help

[Babcock_Hall]

I have made a number of antibacterial solutions, and I have never heard of "units per mg."  More typically mg/mL is provided in tables.  Can you provide any more specifics?

[Arkcon]

No, units per mg is a specialized unit for antibiotics, or maybe some vitamins.  You will have to find a conversion factor for this particular antibiotic.

[vinayaraj]

how can i find this conversion factor..

[vinayaraj]

Accding to CLSI the preparation of antibiotic solution is based on this formula..Wt of the antibiotic to use = volume * concentration(mcg/ml)  / potency (mcg/mg)
but in the case of penicillin or colistin , potency is expressed as units/mg. how do i prepare based on this data..pls help me..

[Arkcon]

According to the very first Googlle result, right here:  http://www.rxlist.com/penicillin-vk-drug.htm

Each 5 mL of reconstituted penicillin V potassium (penicillin v potassium) for oral solution, USP, 125 mg (200,000 units) per 5 mL contains 0.36 mEq (13.9 mg) of potassium. Each 5 mL of reconstituted penicillin V potassium (penicillin v potassium ) for oral solution, USP, 250 mg (400,000 units) per 5 mL contains 0.71 mEq (27.9 mg) of potassium.

You can't use this information as is, because we don't know exactly what you have.  Such information should be available from the manufacturer of your antibiotic.  But you can see, a certain number of mg equals a certain number of "units."

[vinayaraj]

TEST Specification
________________________________________________________________________
for example I got a colistin sulfate salt drug from sigma.the following are the specification received from the company.
Appearance (Color) White to Off-White
Appearance (Form) Powder
Solubility (Color) Yellow
Solubility (Turbidity) Clear 50 mg/mL, H2O
Identity Pass by BP Test C
Identity Pass by BP test D
Potency > 15000 UN/mg
if i want to prepare a 10ml stock solution of concentration 1028 mcg/ml,how do i get the requied amount of abt powder...do you think something is missing from specification received from the company..

[vinayaraj]

for Colistin sodium methanesulfonate, they have given following information
Empirical Formula (Hill Notation) C58H115N16Na5O28S5  Molecular Weight 1759.9
ign. residue      ~20%
loss      ≤1.5% loss on drying
pH      6-8 (10 mg/mL in H2O)
solubility      H2O: soluble10 mg/mL

[Arkcon]

You've found a number of facts, and we can now work together to find the answer to your question.  That's what we do here, as you can read That's what this forum is really all about.  Check the Forum Rules{click}.

Now it seems you need to build a standard solution for some analytical process.  You want a certain number of ug per mL.  How would you build such a solution if the substance was pure NaCl?  What is different about this product that stops you from solving this problem the same way?  And what bit of information do you think you need from your list of statistics to solve this problem