Interpreting the Language of Prescriptions

When you’re calculating drug dosages, it’s important to understand medical abbreviations. Misunderstanding them can lead to medication errors. If you’re unsure about what a medical abbreviation stands for, if the handwriting is illegible, or if you have any question about the medication order or prescription, do not prepare the dose. Clarify the order, prescription or abbreviation with the healthcare provider who prescribed the medication.

Below are three sample medication orders. They may look confusing now, but after you’ve worked your way through this chapter, they’ll make perfect sense:

Morphine sulfate 15 mg Sub Q stat and 10 mg q4h prn

Chloromycetin 0.01% Ophth Oint left eye bid

Ampicillin 1 g IVPB q6h

In 2004, the Joint Commission issued a list of “Do Not Use” abbreviations—the ones that were often misread and thus led to medication errors. Some of them (clearly labeled “Do Not Use”) appear in this book, either because they are from the minimal required list on the Joint Commission’s Web site or because they supplement that list. To see a complete roster of abbreviations designated “Do Not Use,” go to www.jointcommission.org or search “prohibited abbreviations.” Each institution may also have its own “Do Not Use” list. As a nurse, you need to make careful note of abbreviations that are prohibited or dangerous.

Time of Administration of Drugs

The abbreviations for the times of drug administration appear in the following table. Most of these abbreviations come from Latin words and are given for your reference. Memorize the abbreviations, their meanings, and the sample times that indicate how the abbreviations are interpreted. However, follow your institutional policy for administration times.

The time abbreviations in the following table are based on a 24-hour day. To determine the number of times a medication is given in a day, divide 24 by the number given in the abbreviation.

There are four additional time abbreviations that require explanation. They are as follows:

Military Time: The 24-Hour Clock

If a handwritten prescription does not clearly distinguish “AM” from “PM,” confusion about times of administration can arise. To prevent error, many institutions have converted from the traditional 12-hour clock to a 24-hour clock, referred to as military time. (This text will continue using the normal 12-hour clock.)

The 24-hour clock begins at midnight as 0000. The hours from 1 AM to 12 noon are the same as traditional time; colons and the terms AM and PM are omitted (Fig. 3-1). Examples:

The hours from 1 PM continue numerically; 1 PM becomes 1300. To change traditional time to military time from 1 PM on, add 12. To change military time to traditional time from 1300 on, subtract 12. Examples:

FIGURE 3-1
Example of a military, or 24-hour, clock.

Routes of Administration

The abbreviations for routes of administration are given in the following table. Latin words are given for reference only. Note the “Do Not Use” abbreviations. Figure 3-2 shows the use of several abbreviations for routes of administration.

FIGURE 3-2
Label states the routes of administration. Epinephrine may be administered intramuscularly (IM) or subcutaneously, or by intravenous (IV) or intracardiac (IC) routes after dilution. (Courtesy of Abbott Laboratories.)

Metric and SI Abbreviations

Metric abbreviations in dosage relate to a drug’s weight or volume and are the most common measures in dosage. The International System of Units (Système International d’Unités; SI) was adapted from the metric system in 1960. Most developed countries except the United States have adopted SI nomenclature to provide a standard language of measurement.

Differences between metric and SI systems do not occur in dosage. The meaning and abbreviations for weight and volume are the same. Weight measures are based on the gram; volume measures are based on the liter.

Study the meaning of the abbreviations listed in the following table. In the Explanation column, you’ll see one equivalent for each abbreviation to help you understand what kinds of quantities are involved. Equivalents (metric, household, apothecary) are discussed in Chapter 2. The preferred abbreviation is listed first; variations appear in parentheses.

Apothecary Abbreviations

Apothecary measures were common in the United States as far back as colonial times. Today, apothecary measures are discouraged for several reasons: (1) Equivalency with the metric system is not exact, (2) the system requires Roman numerals and fractions, and (3) apothecary symbols can easily be misinterpreted. These apothecary terms are in minimal use:

Household Abbreviations

Physicians and healthcare providers may use these common household measures to order drugs, especially if the drug is to be administered at home. The Explanation column shows metric equivalents.

Terms and Abbreviations for Drug Preparations

The following abbreviations and terms are used to describe selected drug preparations. Some of these abbreviations are rarely used yet are included here for reference.

Now consider the formerly confusing orders that appeared at the beginning of this chapter.

Original: Morphine sulfate 15 mg Sub Q stat and 10 mg q4h prn

Interpretation: Morphine sulfate 15 mg subcutaneously immediately and 10 mg every 4 hours as needed.

Original: Chloromycetin 0.01% Ophth Oint left eye bid

Interpretation: Chloromycetin 0.01% ophthalmic ointment left eye twice a day.

Original: Ampicillin 1 g IVPB q6h

Interpretation: Ampicillin 1 gram intravenous piggyback every 6 hours.

Drug Labels

An understanding of drug labels and the ways in which drugs are packaged provides a background for dosage and administration.

Labels contain specific facts and appear on drugs intended to be administered as packaged: either in solid form or in liquid form. Occasionally the label does not include some details—such as route of administration, usual dose, and storage—because the container is too small. When you need more information than the label provides, consult a professional reference. Figure 3-3 shows a sample drug label.

NDC NUMBER. The National Drug Code (NDC) is a number used by the pharmacist to identify the drug and the method of packaging.

In Figure 3-3, the NDC is 0165-0022-10. The letters NSN (not shown) mean “national supply number,” a code for ordering the drug.

DRUG QUANTITY. This information always appears on the label at either the top left, the top right, or at the bottom.

Figure 3-3 indicates 1000 tablets.

TRADE NAME. A drug’s trade name (also called brand name or proprietary name) is usually followed by the federal registration symbol ®. Several companies may manufacture the same drug, using different trade names. When a trade name appears on the label, it may be written either in all capital letters or with only the first letter capitalized.

In Figure 3-3, MagOx400 is the trade name.

GENERIC NAME. The generic name is the official accepted name of a drug, as listed in the United States Pharmacopeia (USP). A drug may have several trade names but only one official generic name. The generic name is not capitalized.

The generic name given in Figure 3-3 is magnesium oxide.

FIGURE 3-3
Label of MagOx

DRUG STRENGTH. For solid drugs, the label shows metric weights; for liquid drugs, the label states a solution of the drug in a solvent.

In Figure 3-3, the strength is 400 mg.

DRUG FORM. The label specifies the type of preparation in the container.

Figure 3-3 indicates that the drug is dispensed in tablets.

USE. The label may include the indication for the drug.

Figure 3-3 states “Magnesium helps to sustain the performance of your heart, muscles, nervous system, bone structure and cell function. Magnesium may be depleted during illness (such as hypertension, arrhythmias, diabetes and other chronic conditions) and associated treatment (such as diuretics, cisplatin, cyclosporine or amphoterican B)”.

USUAL DOSAGE. The dosage information states how much drug is administered at a single time or during a 24-hour period. It also identifies who should receive the drug.

Figure 3-3 states, “Usual dosage: take 1 tablet daily or as directed by your physician.”

ROUTE OF ADMINISTRATION. The label specifies how the drug is to be given: orally, parenterally (through an injection of some type), or topically (applied to skin or mucous membranes). If the label does not specify the route, the drug is in an oral form.

In Figure 3-3, the route is oral.

STORAGE. Certain conditions are necessary to protect the drug from losing its potency (effectiveness), so this information is crucial. Some drugs come in a dry form and must be dissolved (i.e., reconstituted). The drug may need one kind of storage when it’s dry and another kind after reconstitution.

Figure 3-3 specifies storing the drug at room temperature.

PRECAUTIONS AND WARNINGS. The label may include specific instructions—related to safety, effectiveness, and/or administration—that the nurse must note and follow.

Figure 3-3 shows these precautions: “Do not purchase or use if tamper-evident inner foil seal is broken or missing. Also, Warnings: Consult a physician before use if you are taking a prescription drug. If you are pregnant, nursing a baby, or have kidney disease, consult a physician. May have a laxative effect. The label also states, When using this product: Do not take more than 2 tablets in a 24-hour period. If symptoms persist for more than 2 weeks, consult a physician. Keep out of reach of children.”

FIGURE 3-4
Label of Augmentin for oral suspension. (Reproduced with permission of GlaxoSmithKline.)

MANUFACTURER’S NAME. If you have any question about the drug, direct them to the manufacturer.

In Figure 3-3, the manufacturer is Blaine Pharmaceuticals.

EXPIRATION DATE. A drug expires on the last day of the indicated month. After that date, the drug cannot be used.

Figure 3-3 shows 4-05 as the expiration date.

LOT NUMBER. This number indicates the batch of drug from which the stock came.

Figure 3-3 shows B030120B as the lot number.

ADDITIVES. The manufacturer may have added substances to the drug, for various reasons: to bind the drug, to make the drug dissolve more easily, to produce a specific pH, and so on. Information about such additives may appear on the label or in the literature accompanying the drug.

Additives are not shown in Figure 3-3; however, the label states that the product is “sugar & gluten free”

DRUG RECONSTITUTION. In figure 3-4, the drug Augmentin comes in powder form. Prepare suspension at time of dispensing. The label states, “Add approximately 2/3 of total water for reconstitution (total = 90 mL); shake vigorously to wet powder. Add remaining water; again shake vigorously.” This provides 100 mL suspension. Reconstituted solution contains 125 mg amoxicillin and 31.25 mg clavulanic acid (as clavulanate potassium) per 5 mL solution.

Combination Medications

Some medication labels indicate more than one drug in the dose form. These combination drugs are ordered according to the number of tablets to give or the amount of liquid to pour.

EXAMPLE

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