Application of Measurement and Dose Conversion

The measurement of temperature with 0 degrees representing the freezing point and 100 degrees representing the boiling point of water.

Dosage Strength

Weight of medication in a dose (mEq, mcg, mg, G).

Fahrenheit

The measurement of temperature with 32 degrees representing the freezing point and 212 degrees representing the boiling point of water.

Inscription

The part of the prescription that identifies the medication and dosage.

Medication Order

Directions for administration of medication; these may be written or verbal orders.

Quantity

The amount of medication that is to be dispensed.

Refills

The number of times the physician will allow the prescription to be repeated.

Route

How the medication is to be given.

Signa (Sig)

The part of the prescription that indicates the dosage and frequency with which the medication is to be given.

Objective 1

Have you ever read the label on a pill bottle after a prescription has been filled? Many times, you will see a mixture of metric and U.S. Customary (household) measurements (Figure 9-1). Then the pharmacist hands you a measuring device with both metric and U.S. Customary (household) measurements on it (Figure 9-2). You want to give or take the correct dose, but which do you use—milliliters or teaspoons?

Figure 9-1 Script with medication order. (Modified from Fulcher RM, Fulcher E: *Math calculations for pharmacy technicians: A worktext*, St. Louis, 2007, Saunders.)

Figure 9-2 Measuring cup used to dispense liquid medication. (From Kee J, Hayes E: *Pharmacology: A nursing process approach,* St. Louis, 2004, Saunders.)

In the previous chapters, all of the questions dealt with the same base measurements. In this chapter, however, we practice converting between metric, apothecary, and U.S. Customary (household) measurements. The chapter also discusses common abbreviations used in the health care field, interpretation of physician orders, and conversion of temperature measurements from Fahrenheit to Celsius.

Objective 2

Common abbreviations used in the health care field

Have you ever taken a foreign language class? Medical terms and abbreviations used in the health care field can be compared to a foreign language. Because the medical field has a Latin word base, translations may not be obvious.

Tables 9-1 and 9-2 identify common abbreviations that are used when giving orders in the health care field. It is important that all health care professionals understand and can interpret common abbreviations—these abbreviations are not exclusive to the study of pharmacology.

TABLE 9-1

Abbreviations Commonly Used by Pharmacology and Nursing Health Care Workers

Abbreviation	Meaning
a.c.	Before meals
Ad lib	As desired
a.m.	Morning
bid	Twice a day
BP	Blood pressure
c¯	With
d	Day
d/c	Discontinue
H, hr	Hour
hs	Hour of sleep
IM	Intramuscular
IV	Intravenous
K	Potassium
Na	Sodium
npo	Nothing by mouth
pc	After meals
p.m.	Afternoon
PO	Per oral or by mouth
prn	As needed
Q, q	Every
qid	Four times a day
qs	Quantity sufficient
	Prescription
s¯	Without
SC, SQ, Subq	Subcutaneous
Sig	Directions
SL	Sublingual, under the tongue
STAT	Immediately
Tab	Tablet
tid	Three times a day
TPR	Temperature, pulse, respiration
VO	Verbal order
VS	Vital signs

TABLE 9-2

Abbreviations Commonly Used by Laboratory and Nursing Health Care Workers

Abbreviation	Meaning
BM	Bowel movement
CBC	Complete blood count
CMP	Comprehensive metabolic panel
FBS	Fasting blood sugar
Hct	Hematocrit
Hgb	Hemoglobin
H/H	Hemoglobin and hematocrit
Plat.	Platelets
WBC	White blood count

The frequency of an order can be confusing. The abbreviation BID, which means “twice a day,” is not the same as q2h, which means “every 2 hours.” When requesting that a procedure, therapy, or medication be given at a specific time interval, the physician writes the hour frequency as a number.

Example:

Unasyn 500 mg IV

Q8H × 3 days

The above example Q8H means to give the medication every 8 hours. This order is more specific than tid (three times a day).

Objective 3

Interpretation of physician’s orders

Physician’s orders are given by the physician either in writing or orally to communicate what medication, tests (e.g., laboratory), or therapy he or she would like to have implemented. Orders are written in the patient’s chart by designated health care personnel. Medical abbreviations are commonly mixed in with longhand descriptions of the orders.

Example:

CBC q6h × 3 days then D/C.

Interpretation: Draw blood for a complete blood count every 6 hours for 3 days, then discontinue.

All physician’s orders should have the same basic information—what is to be done and how often.

Medication orders and prescriptions must include specific information (Figure 9-3):

Figure 9-3 Interpreting a prescription. (From Fulcher RM, Fulcher E: *Math calculations for pharmacy technicians: A worktext*, St. Louis, 2007, Saunders.)

1. Name of the medication	Inscription
2. Dosage strength of the medication	Inscription
3. How the medication should be taken	Route
4. How often the medication should be taken	Frequency or Signa (Sig)
5. How much medication should be dispensed	Quantity
6. How many refills of the medication are allowed

Let’s look at the prescription in Figure 9-3 and identify the required information.

1. Name of the medication	Pen-V-K (correct name: Pen-Vee K)
2. Dosage strength of the medication	250 mg
3. How the medication should be taken	Tablets (by mouth) route
4. How often the medication should be taken	Every 6 hours
5. How much medication should be dispensed	40 tablets
6. How many refills of the medication are allowed	Refills are not specified so there would be no refills