PharmD is a professional pharmacy degree similar to a Doctor of Medicine (MD) or Doctor of Dental Surgery (DDS). As a doctorate, it increasing the responsibilities of pharmacists have in health care systems.

Pharmaceutical calculation is a core part of any pharmacy degree, especially for Pharm D degree. Pharm D students must learn about doses, concentration, and biopharmaceutics parameters.

The use of calculations in pharmacy is varied and broad-based. It encompasses calculations performed by pharmacists in traditional as well as in specialized practice settings and within operational and research areas in industry, academia, and government organization.

#### Pharmaceutical Calculation Topics for Pharm D Students

#### Success in performing pharmaceutical calculations is based on the:

- understanding of the purpose or goal of the problem;
- assessment of the arithmetic process required to reach the goal; and,
- implementation of the correct arithmetic manipulations.

This initial article is intended to remind the students of some previously learned mathematics. Most students likely will progress rapidly through this article.

#### Dosage Calculation Conversion Chart

- 1 kg = 2.2 lb
- 1 lb = 16 oz
- 1 tsp = 5 mL
- 1 gallon = 4 quart
- 1 L = 1,000 mL
- 1 kg = 1,000 g
- 1 oz = 30 mL = 2 tbsp
- 8 oz = 240 mL = 1 glass
- 1 g = 1,000 mg
- 1 inch = 2.54 cm
- 1 mg = 1,000 mcg
- 1 cm = 10 mm
- 1 cup = 8 fl oz
- 1 tbsp = 15 mL
- 1 pint = 2 cups
- 12 inches = 1 foot
- 1 L = 1.057 qt
- 1 tbsp = 3 tsp
- 60 minute = 1 hour
- 1 cc = 1 mL
- 2 pints = 1 qt
- 1 pt = 500 mL = 16 oz
- 1 tsp = 60 gtt
- 1 oz = 30 mL
- 4 oz = 120 mL (Casey, 2018)

#### Prescription Abbreviations List

- po: by mouth (or orally)
- susp: suspension
- pm: as needed
- tab: tablet
- IM: intramuscularly
- IV: intravenous
- cap: capsule
- q: every
- bid: twice a day
- tid: three times a day
- qid: four times a day
- qhs: before bed
- ac: before meals
- pc: after meals
- prn: as needed

#### Pharmaceutical Calculation Example

**Practice 1:**

If the adult dose of a medication is 2 teaspoonsful (tsp.), calculate the dose for a child if it is 1/4 of the adult dose.

1/4 x 2 tsp. = 2/4 = 1/2 tsp.

**Practce 2:**

If a child’s dose of a cough syrup is 3⁄4 teaspoonful and represents 1⁄4 of the adult dose, calculate the corresponding adult dose.

3/4 tsp. ÷ 1/4 = 3/4 tsp. x 4/1 = (3x4) ÷(4x1) tsp. = 12÷4 tsp. = 3 tsp.

**Practice 3: **

Order: Doxycycline 100 mg po daily

Supply: Doxycycline 0.2 g (200 mg) per tablet

Give: 100/200 x 1 tablet = 1/2 tablet

#### SOME ARITHMETIC SYMBOLS USED IN PHARMACY

**Related:** Pharm D Syllabus in USA

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