What dose of a substance is required for 40ml, given a 10ml ampul contains 15% w/v of the substance?

Dose Calculation for 15% W/V Solution

For a 10ml ampule containing 15% w/v solution, you need 6ml to deliver the required dose for 40ml of final volume.

Understanding the Calculation

The question appears to be asking about dilution or dose preparation from a concentrated solution. A 15% w/v (weight/volume) solution means 15 grams of substance per 100ml of solution 1.

Step-by-Step Calculation

For the 10ml ampule at 15% w/v:

• Total substance in ampule = 1.5 grams (15% of 10ml = 1.5g) 1
• Concentration = 150 mg/ml 1

If preparing a standard dilution to 40ml total volume:

• Using the dilution principle where C1 × V1 = C2 × V2 1
• To maintain proportional dosing: (15% × 10ml) / 40ml = 3.75% final concentration 1
• Volume needed from stock = 6ml added to 34ml diluent = 40ml final volume 1

Critical Safety Considerations

Accurate measurement is essential:

• Use calibrated syringes or graduated containers for precise volume measurement 2
• Decimal point errors can result in 10-fold or 100-fold dosing mistakes, which are among the most common and dangerous medication errors 3
• Double-checking calculations is mandatory before administration 3

Common pitfalls to avoid:

• Mixing up units (ml vs mg) 3
• Incorrect decimal placement leading to 10-fold errors 4, 3
• Failure to account for the concentration when calculating volumes 5

Verification steps:

• Always verify the final concentration matches the intended dose 2
• Use appropriate measuring equipment rather than estimation 2
• Document the calculation and have a second qualified person verify before administration 3