Understanding Pharmacology for Health Professionals

CHAPTER

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Drug Forms CHAPTER CONTENTS Drug Forms Quiz Yourself Spelling Tips

Clinical Applications Multimedia Extension Exercises

Learning Objectives After you study this chapter, you should be able to 1. Name eleven forms in which drugs are manufactured. 2. Describe seven different types of tablets. 3. Describe the difference between a solution and a suspension. 4. Name eight different types of drugs that come in a solution form. 5. Describe how pellets, beads, and wafers are used as drug forms.

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6. Define these words and phrases: ampule, elixir, lozenge, transdermal patch, and vial.

Understanding Pharmacology for Health Professionals, Fourth Edition, by Susan M. Turley, MA (Educ), BSN, RN, RHIT, CMT. Published by Prentice Hall. Copyright © 2010 by Pearson Education, Inc.

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UNIT ONE • THE PAST HISTORY, PRESENT USES, AND FUTURE OF DRUGS

B

efore a drug can receive final approval by the FDA, the drug company must clearly state in what form or forms the drug will be manufactured. Different forms of a drug are appropriate for different routes of administration. Some drugs are ineffective when administered in a certain form; other drugs can seriously injure the patient if administered in the wrong drug form.

Drug Forms Drugs are manufactured in the following different forms. 1. Tablet. A tablet is a solid drug form that contains an active drug (as a dried powder) plus inert ingredients (binders and fillers) to provide bulk and ensure a standardized tablet size. In written prescriptions, tablet is sometimes abbreviated as tab or tabs. Tablets come in many colors, many standard shapes (round, oval, square, oblong), and some unusual shapes (triangle, baseball-diamond shape [see ■ FIGURE 3–1], pentagon, hexagon, and others). Example: Tablets of Cialis, a drug used to treat erectile dysfunction, are mustard colored and manufactured in the shape of a teardrop. Example: Tablets of Valium, a drug used to treat anxiety, have a tiny, V-shaped opening cut in the center of each tablet.

■ FIGURE 3-1 Drug label

for over-the-counter Zantac. Over-the-counter Zantac also comes in a 75 mg strength. Zantac is a nonprescription acid reducer available for prevention and relief of heartburn associated with acid indigestion and sour stomach.

Clinical Applications A 2006 survey of pharmacists found that a tablet with a unique color and shape, one that had the drug name and dose imprinted on it, and one that had a distinctive aroma was the best combination to help positively identify the drug and decrease drug errors. Nearly 70 percent of pharmacists report that patients ask them weekly to identify tablets or capsules that have been taken out of the original packaging. The Food and Drug Administration (FDA) advises patients who take more than one drug to be able to tell them apart by size, shape, color, imprint, or drug form.


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Tablets are also manufactured in several specialized types: scored tablet, effervescent tablet, enteric-coated tablet, slow-release tablet, caplet, lozenge, and troche. A scored tablet has an indented line running across it, from one side to the other, so that it can be easily broken into equal pieces to produce an accurate, but reduced, dose (see ■ FIGURE 3–2).

CHAPTER 3 • DRUG FORMS

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■ FIGURE 3–2 Scored tablets. A scored tablet can be divided easily and accurately. These scored tablets can be divided into two or three equal doses, depending on the number of score marks on the tablet.

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“While the doctor’s trying to split one of the tablets he prescribed, I thought I’d give you a call.”

An effervescent tablet is one that is dissolved in a glass of water before being swallowed (e.g., Alka-Seltzer for a head cold). An enteric-coated tablet is covered with a special coating that resists stomach acid, but dissolves in the alkaline environment of the small intestine to avoid irritating the stomach (e.g., Ecotrin for pain). The ec in the trade name Ecotrin reminds that it is enteric coated). A slow-release tablet is manufactured to provide a continuous, sustained release of the drug. The drug’s trade name often includes the abbreviation CR (controlled release), LA (long acting), SR (slow release), or XL (extended length). Caplets are coated tablets in the form of an elongated capsule. Some over-the-counter drugs come in the form of lozenges. These tablets are formed from a hardened base of sugar and water containing the drug and other flavorings. Lozenges are never swallowed whole, but are allowed to disintegrate slowly into a liquid form that releases the drug topically in the mouth and throat (e.g., Cepacol lozenge for a sore throat). A troche is an oblong tablet that has a base of sugar and disintegrates into a paste to release the drug topically in the mouth (e.g., Mycostatin Pastilles for a yeast infection in the mouth. A pastille, a French word that means little lump of bread, is another name for a troche).


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2. Capsule. A capsule comes in two varieties. The first is a soft, one-piece gelatin shell with the liquid drug inside (e.g., fat-soluble vitamins such as A and E). The second type of capsule is a hard shell manufactured in two pieces that fit together and hold the powdered or granular drug inside (see ■ FIGURE 3–3). In written prescriptions, the word capsule is sometimes abbreviated as cap or caps. Hard shell capsules come in a variety of colors.

■ FIGURE 3–3 Hard shell capsules. The trade name drug Cardizem is used to treat hypertension. It comes in a blue and white, hard shell capsule that contains the drug in a granular form.

Example: Nexium, a drug used to treat heartburn and ulcers, is a distinctive deep purple–colored capsule with three gold bands around one end and the drug name in large letters. Its marketing campaign is built around the phrase “the little purple pill.” Even its Website www.purplepill .com is done in purple!

Historical Notes Many over-the-counter cold remedies and drugs to treat pain were manufactured as capsules until some Tylenol capsules were purposely contaminated with cyanide in the early 1980s. Now, most drug companies manufacture their over-the-counter drugs for pain in a tablet or caplet form that prevents tampering with the contents. Many prescription drugs, however, are still manufactured as two-piece, hard shell capsules.


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3. Ointment. An ointment is a semisolid emulsion of oil (lanolin or petroleum) and water, the main ingredient being oil (see ■ FIGURE 3–4 and ■ TABLE 3–1). Many topical drugs are manufactured in an ointment base (e.g., Kenalog ointment for skin inflammation). Specially formulated ophthalmic ointments can be applied topically to the eye without causing irritation. Ointments are absorbed into the area to which they are applied; most exert a local, not systemic, drug effect.


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■ FIGURE 3–4 Ointment and cream drug forms. These over-the-counter drugs are triple antibiotic ointment and hydrocortisone cream. The feel, appearance, and consistency of the two drug forms are different.

4. Cream. A cream is a semisolid emulsion of oil (lanolin or petroleum) and water, the main ingredient being water (see ■ FIGURE 3–4). Emulsifying agents are added to keep the oil and water mixed together. Many topical drugs are manufactured in a cream base (e.g., hydrocortisone cream for skin inflammation). Creams are absorbed into the skin and exert a local, not systemic, drug effect. 5. Lotion. A lotion is a suspension of a drug in a water base (e.g., Keri lotion or Calamine lotion for skin dryness and irritation). Lotions are absorbed into the skin and exert a local, not systemic, drug effect.

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■ TABLE 3–1 Comparison of ointment, cream, and lotion drug forms Drug Form

Feel

Appearance

Consistency

Dispensed from

Ointment

Greasy

Clear

Firm

Tube

Cream

Nongreasy

Opaque/milky

Semiliquid

Tube or bottle

Lotion

Nongreasy

Opaque/milky

Liquid

Bottle

6. Powder. A powder is a finely ground form of a drug. Powdered drugs can be found within capsules; they are also placed in glass vials where they must be reconstituted with sterile water before they can be injected (e.g., powdered ampicillin, an antibiotic drug in a vial). Powders come in individual packets. The powder is reconstituted with water for oral use (e.g., Metamucil, a laxative). Powders can also be sprinkled topically or sprayed onto the skin (e.g., Tinactin, an antifungal drug for the skin). Powders also come in a canister that is activated and the powder is inhaled into the lungs with the help of a special inhalation device (e.g., Serevent Diskus, a bronchodilator drug). 7. Liquid. A liquid drug comes in the form of a solution or a suspension. Two general words used to describe liquid drugs are aqueous (from the Latin word aqua, water), meaning of a watery consistency, and viscous, meaning nonwatery or thick.


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Solutions contain the drug in a base of sterile water, saline, or water and alcohol. Solutions never need to be mixed, as the drug concentration is always the same in every part of the solution, even after prolonged standing. Solutions come in three forms. A. Solutions in which the drug is dissolved in sterile water or saline for injection into body tissue or the blood. These drugs are packaged in ampules (see ■ FIGURE 3–5) or vials (see ■ FIGURE 3–6).

■ FIGURE 3–5 Ampule. An ampule is a small, slender glass container with a main body and a narrow, extended top. An alcohol swab is placed around the neck (narrowed indentation) of the ampule, and the ampule is quickly snapped into two pieces. A syringe is used to withdraw the drug solution from the body of the broken ampule. An ampule can be used only once and the remaining, unused drug must be discarded because it contains no preservative. This ampule contains the liquid drug Narcan, which is used to treat an overdose of narcotic drugs.

■ FIGURE 3–6 Vial. A vial is a small glass bottle. The top has an aluminum cap that protects a rubber stopper beneath until the vial is opened. To withdraw the liquid drug from a vial, the vial is turned upside down, the needle of a syringe is inserted through the rubber stopper, air is injected into the vial, and the drug dose is withdrawn. A vial can be used multiple times. The rubber stopper is cleansed with alcohol before each dose is withdrawn. This vial contains the liquid drug atropine, which is used to treat an abnormally slow heart rate. Some vials contain a powdered drug that must be reconstituted to a liquid before it can be drawn up into the syringe.


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B. Solutions in which the drug is dissolved in a liquid base (elixirs, syrups, tinctures, liquid sprays, foams, mousse) are for topical or oral administration. Elixirs are solutions that contain the drug in a water and alcohol base with added sugar and flavoring (e.g., Tylenol elixir for fever and pain). Elixirs are commonly used for pediatric or elderly patients who cannot swallow the tablet or capsule form of a drug (see ■ FIGURE 3–7).


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■ FIGURE 3–7 Elixir. Digoxin elixir is used to treat congestive heart failure in children. Notice the illustration of the calibrated dropper on the label. The dropper allows a very precise, small dose of the elixir to be given.

Syrups are solutions that contain the drug in a thickened water base with added sugar and flavorings, but no alcohol. Syrups are sweeter and more viscous (thicker) than elixirs. Most over-the-counter cough drugs are syrups that coat the mucous membranes for a soothing effect in addition to the drug effect (e.g., Robitussin for coughs). Tinctures are solutions that contain the drug in a water and alcohol base (e.g., topical iodine tincture to disinfect the skin). Tinctures are never taken internally. Liquid sprays are solutions that contain the drug in a water or alcohol base. They are sprayed manually by a pump or by squeezing a bottle or they are forced from a can by an aerosol propellant. Spray liquid drugs are commonly used for topical application (example: Afrin nasal spray, a decongestant drug). Foams are solutions that contain the drug in a water base that is expanded by tiny aerosol bubbles when expelled from the container (e.g., over-the-counter contraceptive foams; Rogaine foam for male baldness). Mousse is a solution that contains the drug in a thickened alcohol base. It is expanded by tiny aerosol bubbles when expelled from the container (e.g., RID mousse to kill lice on the body). C. Solutions in which the drug form remains separate from the base (emulsions, gels) but is still evenly distributed throughout the solution. Even though the drug particles never dissolve in the base, they never settle to the bottom over time, so they do not need to be shaken prior to administration. Emulsions are solutions that contain fat globules dispersed uniformly throughout a water base (e.g., Intralipid intravenous fat solution). Gels are solutions that contain fine, undissolved drug particles dispersed uniformly throughout a thickened water base (e.g., MetroGel for acne rosacea).

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Did You Know? Liquid drugs that are given orally come in a variety of flavors to please everyone and “help the medicine go down”: grape, cherry, bubblegum, pineapple, maple, wine, raspberry, mocha, butterscotch, strawberry, mint, orange, honey lemon, root beer, watermelon, coconut, licorice, banana, etc.


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“I think you’ll like this new medication, p it’s a little spritzy, sweet and spicy with some bite, but not abrupt p and it has a rich, toasted almondpeach aftertaste with lots of character.” Suspensions contain fine, undissolved particles of a drug suspended in a water or oil base (see ■ FIGURE 3–8). After prolonged standing, these fine particles gradually settle to the bottom of the container (due to the action of gravity). It is always important to shake suspensions well before using them, a fact that is noted on the label of the drugs (e.g., Maalox, an antacid drug).

■ FIGURE 3–8 Suspension form of a drug. This drug label is for the antibiotic drug azithromycin (Zithromax). It is in the form of a powder that is reconstituted with water to make an oral suspension. Notice the fine print (bottom left) that says “Shake Well Before Using,” because the fine drug particles of a suspension will settle to the bottom of the container over time.


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8. Suppository. A suppository is composed of a solid base of glycerin or cocoa butter that contains the drug. Suppositories are manufactured in appropriate sizes for vaginal or rectal insertion and also come in adult and pediatric sizes. Vaginal suppositories are used to treat vaginal yeast infections, but can also be inserted into the mouth to treat oral yeast infections. Rectal suppositories can be used to administer drugs to patients who are vomiting and cannot take oral drugs. 9. Transdermal patch. Transdermal patches contain drugs and are applied to the skin (see ■ FIGURE 3–9 and ■ FIGURE 3–10). The patch releases a small amount of drug over a long period of time, usually for one to two days. The drugs in transdermal patches are designed to exert a systemic effect in the body, not a topical effect on the skin.


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■ FIGURE 3–9 Transdermal patch. Transdermal patches release drugs slowly over a long period of time. They are used to treat chronic conditions, such as severe pain, to relieve the urge to smoke, and to prevent angina attacks in patients with heart disease.

Backing layer Drug reservoir Microporous rate-limiting membrane Adhesive layer Skin surface

Blood vessel

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■ FIGURE 3–10 Cross section of a transdermal patch. A transdermal patch consists of a multilayered disk containing a drug reservoir, a porous membrane, and an adhesive layer to hold it to the skin. The porous membrane regulates the amount of drug entering the skin, releasing small amounts over time.

10. Pellet, bead, wafer, insert, and device. A drug in the form of a pellet, bead, wafer, or insert can be placed within a body space or body cavity, where it slowly releases drug to the surrounding tissues (e.g., a Muse pellet inserted into the urethra to treat erectile dysfunction; Septopal beads on a wire implanted in bone to treat chronic infection; a Gliadel wafer, a chemotherapy drug, implanted near a cancerous tumor; Lacrisert inserts placed in the lower eyelid sac to treat dry eye syndrome; Mirena, a T-shaped device, inserted into the uterus to prevent pregnancy). 11. Gas. A drug can be inhaled in the form of a gas (e.g., a general anesthetic gas used during surgery).


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Focus on Healthcare Issues Studies have shown that patients usually take their prescribed drugs accurately only 50 percent of the time. Researchers want to improve that percentage by inventing new drug forms. Development is nearly completed on an artificial tooth that contains a tiny mechanism that is preprogrammed to dispense a drug at specific times. Another drug researcher wants to make drugs in the form of a tasteless powder that can be sprinkled on food. A Massachusetts company has created a computer chip that contains up to 100 doses of a drug; the chip is implanted in the body and receives wireless signals that tell it when to release a drug dose. In the future, drug researchers will work closely with biomedical engineers to create drug forms and drug-delivery technology so small that they are measured in nanometers (billionths of a meter).

Chapter Review Quiz Yourself 1. 2. 3. 4. 5. 6. 7. 8.

What is the reason for manufacturing a drug as an enteric-coated tablet? What are caplets? Besides tablets and capsules, list five other forms in which drugs are manufactured. Describe the difference between an elixir and a syrup. Which drug form contains a built-in drug reservoir? What is the difference between an ampule and a vial? What can be done with a scored tablet that cannot be done with other tablets? What phrase is written on the drug label of a suspension that would not be on the drug label of a solution? 9. A suppository can only be given rectally: true or false? 10. Differentiate between the feel, appearance, and consistency of an ointment versus a cream versus a lotion. 11. What do the abbreviations CR, LA, SR, and XL have in common?

Spelling Tips lozenge no final r, although it is often mispronounced as “lozenger.”

000200010270643129 Understanding Pharmacology for Health Professionals, Fourth Edition, by Susan M. Turley, MA (Educ), BSN, RN, RHIT, CMT. Published by Prentice Hall. Copyright © 2010 by Pearson Education, Inc.


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Clinical Applications 1. Carefully examine this photograph and identify what drug forms are represented by each of the four pictured over-the-counter drugs.

2. This nurse is preparing a drug dose. What two pieces of drug-related equipment are shown here? What form of drug would be in the container?

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Multimedia Extension Exercises ■

Go to www.pearsonhighered.com/turley and click on the photo of the cover of Understanding Pharmacology for Health Professionals to access the interactive Companion Website created for this textbook.
