Question

ordered: gemzar® 150 mg in 750 ml nss over 3h using 15 gtt/ml tubing
dosage available: gemzar® 200 mg/5 ml
a) calculate the dosage in milliliters in ml per dose.
b) calculate the flow rate in milliliters per hour.
c) calculate number of drops per minute in gtt per minute.

Explanation:

Part 1: Calculate the dosage in milliliters per dose

Step1: Use the formula \(V=\frac{D}{H}\times Q\)

Where \(D = 150\) mg (desired dose), \(H=200\) mg (dose on hand), \(Q = 3\) mL (quantity of dose on hand).

$$V=\frac{150}{200}\times3=\frac{450}{200}=2.25$$

mL

Part 2: Calculate the flow rate in milliliters per hour

Step1: Use the formula \(Flow\ rate=\frac{Volume}{Time}\)

The volume is \(750\) mL and the time is \(3\) hours.

$$Flow\ rate=\frac{750}{3}=250$$

mL/hour

Part 3: Calculate the number of drops per minute

Step1: Use the formula \(gtt/min=\frac{Volume\times gtt/mL}{Time\times60}\)

The volume is \(750\) mL, \(gtt/mL = 15\), and the time is \(3\) hours.

$$gtt/min=\frac{750\times15}{3\times60}=\frac{11250}{180}=62.5$$

gtt/min

Answer:

A. \(2.25\) mL
B. \(250\) mL/hour
C. \(62.5\) gtt/min