Medication Calculation Examination Study Guide For Desired D ✓ Solved

Medication Calculation Examination Study Guided Desired Dose Q

Medication Calculation Examination Study Guide D = Desired Dose Q = Quantity of Solution H = Strength on Hand X = Unknown quantity of Drug.

Sample: Physician orders 500 mg of ibuprofen (desired Dose) for a patient and you have 250 mg (Quantity on Hand) tablets (Quantity of solution) on hand.

Solution: D ÷ H x Q = X 500mg ÷ 250 mg x 1 tablet = 2 tablets. Answer: 2 tablets.

Sample: Physician orders 1500 mg of liquid ibuprofen for a patient. Quantity of Ibuprofen is 500 mg in 1 cc, how much will you administer?

Solution: 1500 mg ÷ 500 mg x 1cc = 3 cc. Answer: 3 cc.

Dosage and Conversions: Sample: MD orders 300 mg of Ibuprofen to be taken by a 6 kg infant every 4 hours. Label shows 75 – 150 mg/kg per day.

Is the physician’s order within normal range? Solution: 6 x 75 = 450 mg (minimum dosage per day); 150 x 6 = 900 (maximum dosage per day) 24 ÷ 4 = 6 dosages : 300 x 6 = 1800. Answer: Dosage is not within range.

IV Calculations: [amount of fluid to be infused] x [drop factor] ÷ minutes to infuse = gtts/min.

Sample: Dr. A. orders your patient to receive 125 ml of D5W an hour for the next 8 hours. The nursing unit uses tubing with a drop factor of 10. What is the drip rate per minute?

Solution: Convert 1 hour to 60 minutes: 1250 x 10 gtts ÷ 60 minutes = 20.83 or 21 gtts/min. Answer: 21 gtts/min.

Sample: Dr. B. orders a liter of D5W to run this 8-hour shift. The drop factor is 15. What is the drip rate per minute?

Solution: 1 liter = 1000 cc of solution, 8 hours to minutes (8 x 60 minutes) = 480 minutes. 1000 cc x 15 gtts ÷ 480 minutes = 31.25 or 31 gtts/min. Answer: 31 gtts/min.

Your patient weighs 200 lb and the order is to infuse 250 mg dobutamine in 500 ml NS at 10 mcg/kg/min. How many milligrams of dobutamine will infuse per hour?

Solution: 200 ÷ 2.2 = 90.90 kg: 60 minutes = 1 hour: 10 mcg x 90.90kg x 60 min = 5454.54 mcg/hour ÷ 1000 = 54.54mg/hr or 54.5mg/hr. Answer: 54.5mg/hr.

The “7 Rights” of Medication Administration: Right Patient, Right Drug, Right Dose, Right Route, Right Time, Right Documentation, Right to Refuse.

Conversion Table:

• 1 kilogram (kg) = 1000 grams (g)
• 1 gram (g) = 1000 milligrams (mg)
• 1 milligram (mg) = 1000 micrograms (mcg)
• 1 Grain (gr.) = 60 Milligrams (mg)
• 1ml = 1 cc
• 1 ounce = 30 ml
• 1 tablespoon (T or tbsp) = 15 ml
• 1 teaspoon (t or tsp) = 5 ml
• 2.2 lb = 1 kg

Paper For Above Instructions

Medication calculations are critical skills for healthcare professionals, particularly in nursing and pharmacy. The accurate administration of medications requires the ability to convert dosages and to understand the relationships among the quantities of the desired doses, available medications, and patient-specific factors such as weight. This paper explores the key concepts surrounding medication calculation, including desired dosage calculations, IV flow rates, and essential conversion factors.

Understanding Desired Dosage Calculations

The desired dose calculation is essential in determining how much medication a patient should receive. The formula used in medication calculations can be expressed as:

D ÷ H x Q = X

Where: D is the desired dose, H is the quantity on hand, Q is the quantity of solution, and X is the unknown quantity of the drug.

For instance, if a physician orders 500 mg of ibuprofen and the available tablets are 250 mg each, the calculation would be:

500 mg ÷ 250 mg x 1 tablet = 2 tablets

This answer indicates that the patient should receive 2 tablets of ibuprofen to achieve the prescribed dosage.

IV Calculations and Drip Rates

Intravenous (IV) calculations are equally crucial for ensuring that medications are delivered correctly and safely. The general formula for calculating drip rates is:

[amount of fluid to be infused] x [drop factor] ÷ minutes to infuse = gtts/min

For example, if a patient is to receive 125 ml of D5W over one hour (60 minutes) using tubing with a drop factor of 10, the calculation would be:

125 ml ÷ 60 min x 10 gtts = 21 gtts/min

Such calculations ensure that the patient's medication is administered at the correct rate, thereby minimizing any risk associated with under or over-medication.

Dosage Ranges and Pediatric Considerations

Another critical aspect of medication calculations is verifying whether prescribed dosages fall within the recommended therapeutic ranges, particularly for children. For instance, if a physician orders 300 mg of ibuprofen for a 6 kg infant, the dosage can be calculated based on a pediatric dosage range of 75 – 150 mg/kg per day.

First, we find the range:

Minimum dosage = 6 kg x 75 mg/kg = 450 mg/day

Maximum dosage = 6 kg x 150 mg/kg = 900 mg/day

Given that the order is for 300 mg every 4 hours, which totals 1800 mg in 24 hours, this amount exceeds the maximum safe dosage. Therefore, healthcare professionals must always confirm that orders fall within safe limits before administration.

Conversion Factors

Understanding and utilizing conversion factors are essential for medication calculations, particularly when medications are supplied in various forms and concentrations. Conversion factors for common measurements in medication administration, such as weight, volume, and dosage units, are crucial. For instance:

• 1 kg = 1000 g
• 1 g = 1000 mg
• 1 mg = 1000 mcg
• 1 ml = 1 cc
• 2.2 lb = 1 kg

Knowing how to convert between these units correctly can prevent dosing errors and ensure patient safety.

Conclusion

Mastering medication calculations through practice and familiarity with the formulas, as well as understanding the safety ranges and conversion factors, is essential for all healthcare practitioners. This knowledge not only enhances medication safety but also supports the overall efficacy of patient care.

References

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• Fitzgerald, T. (2020). Clinical calculations: A unified approach. Jones & Bartlett Learning.
• Hughes, R. G. (2008). Patient safety and quality: An evidence-based handbook for nurses. Agency for Healthcare Research and Quality.
• Institute for Safe Medication Practices. (2021). Best practices for using medication safely.
• Karch, A. M. (2019). Focus on nursing pharmacology. Wolters Kluwer.
• Mallilo, J. (2021). A medication calculation workbook for nurses. Pearson.
• McGraw-Hill. (2016). Dosage calculations. Fundamentals of nursing textbook.
• Rogers, M. (2018). Medication Calculation: A Step-by-Step Guide for Nurses. Springer.
• Wong, D. L., & Hockenberry, M. J. (2020). Wong's Essentials of Pediatric Nursing. Elsevier.
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