Dosage Calculations - Pharmacy Technician Certification Exam Ptce

1. How many mg is $0.25\ \text{g}$?

   $250\ \text{mg}$. Multiplying 0.25 by the conversion factor of 1000 mg per gram yields 250 mg.

2. What is the insulin syringe unit-to-mL relationship used on PTCE calculations?

   $100\ \text{units}=1\ \text{mL}$. U-100 insulin concentration means 100 units are contained in 1 mL, standard for syringe calibrations.

3. How many mcg is $0.2\ \text{mg}$?

   $200\ \text{mcg}$. Multiplying 0.2 by the conversion factor of 1000 mcg per mg yields 200 mcg.

4. An IV order is $1000\ \text{mL}$ over $8\ \text{hr}$. What is the rate in $\text{mL/hr}$?

   $125\ \text{mL/hr}$. Dividing total volume by total hours gives the infusion rate in mL per hour.

5. What is the formula for quantity to dispense in tablets when dose is $D$ (mg) and strength is $S$ (mg/tab)?

   $\text{tabs}=\frac{D\ \text{mg}}{S\ \text{mg/tab}}$. The number of tablets is found by dividing the prescribed dose by the strength per tablet.

6. What is the IV drip rate formula in $\text{gtt/min}$ using drop factor $DF$ (gtt/mL)?

   $\text{gtt/min}=\frac{V\ \text{mL}\times DF\ \text{gtt/mL}}{t\ \text{min}}$. The drip rate multiplies volume by drop factor and divides by total minutes to find drops per minute.

7. What is the proportion setup to find volume when label is $C_1$ (mg/mL) and dose is $D$ (mg)?

   $\frac{C_1\ \text{mg}}{1\ \text{mL}}=\frac{D\ \text{mg}}{x\ \text{mL}}$. This proportion equates the given concentration to the desired dose over unknown volume, allowing solution for $x$ via cross-multiplication.

8. Identify the conversion: How many mcg are in $1\ \text{mg}$?

   $1\ \text{mg}=1000\ \text{mcg}$. The metric prefix micro- indicates one-thousandth of a milligram, so 1 mg equals 1000 mcg.

9. What is the percent strength meaning of $1\%$ (w/v) expressed as mg/mL?

   $1\%\ \text{w/v}=1\ \text{g}/100\ \text{mL}=10\ \text{mg/mL}$. Percent strength 1% (w/v) means 1 gram per 100 mL, which converts to 10 mg per mL.

10. Identify the conversion: How many mL are in $1\ \text{L}$?

    $1\ \text{L}=1000\ \text{mL}$. The metric system for volume defines 1 liter as equivalent to 1000 milliliters.

11. What is the formula for mL to administer when dose is $D$ (mg) and concentration is $C$ (mg/mL)?

    $\text{mL}=\frac{D\ \text{mg}}{C\ \text{mg/mL}}$. The volume is calculated by dividing the desired dose by the concentration of the solution.

12. How many tablets are needed for a $750\ \text{mg}$ dose if tablets are $250\ \text{mg}$ each?

    $3\ \text{tablets}$. Dividing the dose by the tablet strength gives the exact number of tablets needed.

13. What volume (mL) provides $40\ \text{mg}$ from a solution labeled $20\ \text{mg}/\text{mL}$?

    $2\ \text{mL}$. Dividing the dose by the concentration directly yields the required volume in mL.

14. What is the ratio strength meaning of $1\!:\!1000$ (w/v) expressed as mg/mL?

    $1\!:\!1000=1\ \text{g}/1000\ \text{mL}=1\ \text{mg/mL}$. Ratio strength 1:1000 (w/v) indicates 1 gram per 1000 mL, equivalent to 1 mg per mL.

15. What is the dimensional analysis rule for selecting conversion factors in a setup?

    Place unwanted units to cancel; keep desired unit uncanceled. Dimensional analysis requires arranging conversion factors to cancel out intermediate units, ensuring only the target unit remains.

16. How many mL are needed for $0.5\ \text{g}$ if the concentration is $250\ \text{mg}/5\ \text{mL}$?

    $10\ \text{mL}$. Converting 0.5 g to 500 mg and using proportion from the concentration gives 10 mL.

17. What is the IV flow rate formula in $\text{mL/hr}$ when volume is $V$ and time is $t$ (hr)?

    $\text{mL/hr}=\frac{V\ \text{mL}}{t\ \text{hr}}$. The flow rate is calculated by dividing total volume by total time in hours to determine milliliters per hour.

18. How many mL contain $25\ \text{units}$ of U-100 insulin?

    $0.25\ \text{mL}$. Dividing units by the U-100 concentration of 100 units per mL gives the volume.

19. Convert $2\ \text{L}$ to mL.

    $2000\ \text{mL}$. Multiplying 2 by the conversion factor of 1000 mL per liter yields 2000 mL.

20. Identify the conversion: How many mg are in $1\ \text{g}$?

    $1\ \text{g}=1000\ \text{mg}$. The metric system conversion defines 1 gram as equal to 1000 milligrams for weight measurements.

21. What is the basic ratio-proportion cross-multiplication rule for $\frac{a}{b}=\frac{c}{d}$?

    $ad=bc$. Cross-multiplying the proportions $\frac{a}{b}=\frac{c}{d}$ results in $ad=bc$, enabling algebraic solution for any unknown variable.

22. What is the concentration in mg/mL of a $2\%$ (w/v) solution?

    $20\ \text{mg/mL}$. 2% w/v means 2 g per 100 mL, which converts to 20 mg per mL.

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