Question

1. A hospice pharmacist receives a prescription for 1% morphine sulfate oral solution. She has a 120 mL bottle of morphine sulfate labeled 20 mg/5 mL and a 240 mL bottle of

morphine sulfate labeled 100 mg/5 mL. How much of the 100 mg/5 mL product must be mixed with the contents of the 20 mg/5mL morphine sulfate bottle to prepare the desired percentage strength for the patient?

Answer 1

Answer 72mL is to be added

Explanation

Required concentration

1% morphine sulphate = 10mg/mL

Bottle 1 -

• volume = 120 mL (V1)
• concentration= 20mg/5mL =4mg/mL=C1

Bottle 2 -

• volume = 240mL, (V2)
• concentration= 100mg/5mL = 20mg/ml (C2)

Required

• Volume = V1 + x = V3 ​​​​​​, where "x" is the mL of bottle 2 added
• Concentration = C3 = 1% = 10mg/mL

Framing it into an equation we get

V1*C1 + x*C2 = V3*C3

(120*4) + (x * 20) = (120+x)*10

480 + 20x = 1200 + 10x

20x - 10x = 1200 - 480

10x = 720

x = 72

Hence we need to add 72mL from Bottle 2 to the 120mL in bottle 1 to attain 1% morphine sulphate solution

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