To calculate doses and administer drugs, you must be familiar with those

abbreviations commonly used in medicine, especially those found in prescriptions and

clients' charts. Table 1-1 is a list of common Latin terms and abbreviations used in

medicine. Tables 1-2 and 1-3 are summaries of common abbreviations used to indicate

times of administration, routes of administration, and dosage forms. Tables 1-4 and 1-5

give symbols or abbreviations for different units of measure.

Roman numerals are used in writing prescriptions. They are used to specify the

amounts of ingredients when the apothecary system is being used. They are used to

specify the number of units (capsules, tablets, powders, suppositories, and so forth) to

be dispensed; for example, "Dispxxiv." And lastly, they are used in the signa or

directions to the client. You should, therefore, be thoroughly familiar with the system of

Roman numerals used in pharmacy. The basic symbols or numerals are:

ss,

1/2

I

1

V

5

X

10

L

50

C

100

D

500

M

1000

These basic numerals may be combined to represent any number, and there are

definite rules for the manner in which they are combined. Upper-case or lower-case

letters may be used for Roman numerals. Prescribers usually prefer uppercase letters,

but they dot the "I" for the sake of clarity. The rules for Roman numerals are as follows:

a. **Fractions**. Except for "ss" meaning one-half (1/2), all other fractions are

represented by Arabic numerals (1/4, 3/8, 1/120, and so forth). (Note: The "ss" may be

written with or without a bar--ss or .)

b. **Repeating Numerals**. Numerals may be repeated. When they are, the

value of the number is repeated. Thus, iii or III is 3 (1+1+1), XXX is 30 (10+10+10), and

CCC is 300 (100+100+100). Any numeral that would be the same as another when

MD0913

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