An Inside Look at Pharmacology

Just the mention of drugs causes all sorts of images to run through our mind: the magic pill that made you feel better when you were under the weather; the stinging injection that left your arm sore for days; the handful of capsules that cost a month's pay; and even the vision of furtive street-corner exchanges.

These impressions are from our experiences as patients or consumers. Healthcare providers, however, view drugs differently because drugs are an integral component of the arsenal used to combat the diseases and physiological changes that disrupt activities of daily living.

A drug is more than a pill. It is a compound of chemical elements that interacts with the body's chemistry causing a chain reaction of events. Drugs are given to achieve a therapeutic effect. However, most drugs also have side effects. Some side affects are desirable and some are not. Healthcare providers must have a thorough understanding of a drug's action in order to effectively prescribe and administer the drug and evaluate the patient's response to the medication.

Throughout this book you'll learn about drugs: how they work; their therapeutic effects; their adverse effects; their interactions with other drugs; how they

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are prescribed; and how they are administered. However, before learning these details, let's begin in this chapter with the basic concepts of pharmacology.

What Is Pharmacology?

Pharmacology is the study of chemicals—drugs—on living tissues and how those chemicals help diagnose, treat, cure, and prevent disease or correct the pathophysiology of living tissues. The term pharmacology is derived from two Greek words: pharmakon, the Greek word for drugs, and logos, the Greek word for science.

Pharmacology has its roots in folklore and tradition that dates back to ancient times when knowledge of the medicinal effects of plants were passed down through generations. By 1240 ad, pharmacology moved from the realm of home remedies to a science where drug standards were established and a measuring system was developed—called the apothecary system—that was used to measure quantities of drugs. Because drugs can vary in strength and purity, pharmacological standards have been developed that govern the manufacturing and control of drugs. The United States Pharmacopeia National Formulary is the only official book of drug standards in the United States. If a drug is included in this book it has met the standards of quality, purity, and strength. These drugs can use the letters U.S.P. following the official name of the drug. Accurate dosage and the reliability of the effect the drug will have on a patient is dependent upon the purity and strength of the drug. Purity is the dilution or mixture of a drug with other materials to give it a form that can be administered. Drugs may vary in the strength of their action. The strength of drugs from plants can depend on where the plant is grown, the age at which the plant is harvested, and how the harvest is preserved. Drug packaging standards determine what information needs to be displayed on packages of drugs. You'll learn more about these later in this book.

In addition to these standards, there are a number of important laws that have been enacted to control the sale and distribution of drugs.

1938 FOOD, DRUG AND COSMETIC ACT

Before 1938 there was no control over pharmaceuticals. This changed when a drug company distributed a sulfa drug to treat pediatric patients. The drugs turned out to be a chemical similar to antifreeze. It was highly toxic and killed more than 100 people, including children.

At the urging of the public, the United States Congress passed the 1938 Food, Drug and Cosmetic Act. This act required:

• Drugs must be proven save for use before they can be sold.

• Inspections of drug manufacturing facilities.

• Safe tolerance levels be identified to prevent the patient from being poisoned.

• Cosmetics and therapeutic devices be controlled.

1952 DURHAM-HUMPHREY AMENDMENT TO THE FOOD, DRUG AND COSMETIC ACT

Until 1952, anyone could distribute drugs. With the passage of the Durham-Humphrey amendment to the Food, Drug and Cosmetic Act of 1938, a group of drugs was defined that could only be purchased if the patient had a prescription from a licensed practitioner.

1962 KEFAUVER-HARRIS AMENDMENT TO THE FOOD, DRUG AND COSMETIC ACT

The Food, Drug and Cosmetic Act of 1938 was amended once more in 1962 with the passage of the Kefauver-Harris Amendment. This amendment tightened controls on drug safety by requiring drug manufacturers to use standard labeling of drug containers. The label lists adverse reactions and contraindications or reasons why the drug should not be used.

1970 COMPREHENSIVE DRUG ABUSE PREVENT AND CONTROL ACT

By 1970, there was widespread abuse of prescription drugs. In an effort to contain this problem, Congress passed the Comprehensive Drug Abuse Prevent and Control Act. This act categorized controlled substances according to a schedule based on potential for abuse.

• Schedule I is reserved for the most dangerous substances that have no recognized medicinal use.

• Schedule II drugs have high abuse potential with accepted medicinal use.

• Schedule III drugs have high abuse potential with accepted medicinal uses.

• Schedule IV and V drugs have lower abuse potential with accepted medicinal uses.

The Source of Drugs

Ask a child where milk comes from and you might be surprised by his answer that it comes from the grocery store. The same might be true if you ask an adult where drugs come from and he answers from the drug store. Both are correct answers, but neither identifies the true source.

Drugs can be purchased from a drug store, but the origins are from one of four sources.

PLANTS

A number of plants have medicinal qualities and have been used for centuries as natural remedies for injuries and illnesses. Pharmaceutical firms harvest these plants and transform them into drugs that have a specific purity and strength sufficient to treat diseases.

An example of a drug that comes from a plant is digitalis. Digitalis is made from leaves of the foxglove plant and is used to treat congestive heart failure and cardiac arrhythmias. Digitalis also strengthens the force of the contractions of the heart.

ANIMALS

Byproducts of animals, including humans, are a source for drugs because they contain hormones that can be reclaimed and given to patients who need increased hormonal levels to maintain homeostasis.

For example, Premarin is a drug that contains estrogen that is recovered from mare urine. This is used as hormonal therapy to manage menopausal symptoms. Insulin is another hormonal drug that is used to regulate blood sugar levels in patients with diabetes mellitus. Insulin can be recovered from humans using DNA technology.

MINERALS

Our body requires trace elements of minerals in order to maintain homeostasis. Minerals are inorganic crystal substances that are found naturally on earth. Patients lacking an adequate level of these materials may take specific mineral-based drugs to raise the level of minerals.

For example, an iron supplement is a common mineral-based drug that is given to patients who suffer iron deficiency, a condition which can lead to fatigue. Iron is a natural metal that is an integral part of body proteins such as hemoglobin that carries oxygen throughout the body. Minerals are obtained from animal and plant sources.

SYNTHETIC/CHEMICAL DERIVATIVES

Great strides in molecular biology and biochemistry enable scientists to create manmade drugs referred to as synthetic drugs. A synthetic drug is produced using chemical synthesis, which rearranges chemical derivatives to form a new compound.

Sulfonamides are a common group of synthesized drugs that are used to treat many infections including bronchitis, pneumonia, and meningitis. Sulfonamides are designed to prevent the growth of bacteria.

HERBALS

Herbals are non-woody plants. Some have medicinal qualities classified as a dietary supplement—not a drug. Unlike drugs that are governed by the Food and Drug Administration, dietary supplements are not tested or regulated and can be sold over-the-counter without a prescription. This lack of monitoring means there are no standards for purity and strength for herbals. Two packages of the same herbal distributed by the same company might have different purity and strength that makes the effect of the herb unreliable. There is no control over the manufacturing process and that can lead to contamination. The law prohibits distributors of herbals from claiming that an herbal can cure a disease. They can only state the effect of the herbal on the body. For example, the manufacturer can say that an herbal increases blood flow to the heart, but cannot say that the herb prevents heart disease.

Herbals can lead to unwanted side effects and undesirable interactions with prescription drugs. For example, ginkgo inhibits platelet aggregation (grouping to form clots) if taken with coumadin, an anticoagulant. The result can be increased bleeding and stroke. Garlic interacts with protease inhibitors used to treat HIV and decreases the effectiveness of the prescribed medication. The interaction of herbals with other drugs can be unpredictable and even dangerous. Healthcare providers should encourage patients to reveal any herbal preparations they are taking.

Drugs Names

One of the most confusing aspects of pharmacology is naming drugs. A drug is given three names. Each is used in a different area of the drug industry. These names are the drug's chemical name, generic name, and brand name.

CHEMICAL NAME

The chemical name identifies chemical elements and compounds that are found in the drug. The chemical name is important to chemists, pharmacists, and researchers who work with drugs at the chemical level.

A chemical name looks strange to anyone who isn't a chemist and is difficult for most of us to pronounce. That's why names other than the chemical name are given to a drug. Here is the chemical name for a commonly used drug: N-acetyl-p-aminophenol.

GENERIC NAME

The generic name of a drug is the universally accepted name and considered the official proprietary name for the drug. The generic name appears on all drug labels and is the official name listed in official sources such as the Physicians Desk Reference (PDR). The pharmaceutical company that patents a drug has exclusive rights to sell it until the patent expires. When the patent expires, other drug manufacturers may distribute the drug under the drug's generic name or create a brand name. The generic version of a drug may be cheaper than the original drug and the cost is usually reimbursed by insurance companies. An example of a generic name for a commonly used drug is acetaminophen. The generic name is easier to read and pronounce than the drug's chemical name, N-acetyl-p-aminophenol.

BRAND/TRADE NAME

Drug companies often select and copyright a trade or brand name for their drug. This restricts the use of this name to that particular company. Many brand names may exist for the same chemical compound.

Brand name drugs may be more costly than generic drugs and are partially reimbursed or not covered at all by insurance companies.

A brand name for acetaminophen is Tylenol (patented by Johnson & Johnson Pharmaceuticals).

An example of the correct documentation of the generic and brand name of a drug is: furosemide (Lasix). This drug is a diuretic used for many patients with hypertension (high blood pressure) or cardiac (heart) disease.

Prescription versus Over-the-Counter Drugs

The 1952 Durham-Humphrey Amendment to the Food, Drug and Cosmetic Act requires that certain classifications of drugs be accessible only by prescription from a licensed practitioner. These are commonly referred to as prescription drugs or legend drugs because the drug label must display the legend "Caution: Federal law prohibits dispensing without prescription" on the label of the drug.

Drugs that fall under this classification are:

• Those given by injection.

• Hypnotic drugs (drugs that depress the nervous system).

• Narcotics (drugs that relieve pain, dull the senses and induce sleep).

• Habit-forming drugs.

• Drugs that are unsafe unless administered under the supervision of a licensed practitioner.

• New drugs that are still being investigated and not considered safe for indiscriminate use by the public.

Non-prescription drugs are called over-the-counter (OTC) drugs and are available to the public without prescription. Some over-the-counter drugs were at one time available by prescription, but later were considered safe for use by the public or reformulated for over-the-counter use. Some drugs can be sold in lower doses over-the-counter (OTC) while higher doses of the same drug require a prescription as per FDA requirements.

Drug Effects

Drugs have multiple effects on the body. Some effects are desirable and some are not. The therapeutic effect is the intended physiological effect or the reason the drug is being given. A therapeutic effect can be the drug's action against a disease such as an antibiotic destroying bacteria. Another physiological effect can be the side effects that occur in the body such as nausea and vomiting or a skin rash. A side effect is a physiologic effect that is not the intended action such as the drowsiness that occurs when a patient takes an antihistamine. Some side effects are beneficial while others are adverse effects that can be harmful to a patient.

Healthcare providers must identify all known side effects of a drug and weigh any adverse effects with the therapeutic effect before administering a drug. Patients must also be informed about expected side effects and provided instructions about how to manage adverse side effects if at all possible.

For example, female patients are instructed to drink buttermilk and eat yogurt when taking a broad-spectrum antibiotic. This counters a possible vaginal yeast infection, which is a common adverse effect of broad-spectrum antibiotics. Additionally, a female patient should be instructed to use other forms of birth control when taking this medication because antibiotics lower the effectiveness of birth control pills.

Many times patients will discontinue the use of a medication because the side effects are so unpleasant. Antihypertensive medications (blood pressure medicine) can cause side effects such as drowsiness or the inability to achieve an erection in a male. Patients may decide that this effect is undesirable and discontinue the use of the prescribed drug. Patients should be encouraged to discuss any and all side effects with the provider. Many times, there are alternative medications that can be prescribed. Abruptly discontinuing the use of a drug may not be in the best interest of a patient. Some drugs may be gradually decreased in dose and frequency. Sometimes patients discontinue taking a drug because they feel better, however, the condition being treated is still present. Some examples of these types of medication are antibiotics and antidepressants.

Drug Safety

Drugs must undergo rigorous testing before being approved by the Food and Drug Administration for use in humans. The initial testing is done with animals to determine the toxicity of the drug. Acute toxicity is the dose that is lethal or kills 50% of the laboratory animals tested. The testing is also done to determine what symptoms are experienced by the animals and the time the symptoms appear.

Subchronic toxicity studies, conducted in at least two animal species, usually consist of daily administration of the drug for up to 90 days. Physical examinations and laboratory tests are performed throughout the study and at the end of the study to see what organs may have been adversely affected by the drug.

Chronic toxicity studies, also conducted in at least two species, usually last the lifetime of the animal but the length of the study may depend on the intended duration of drug administration to humans. Three dose levels are used, varying from a nontoxic low-level dose to a dose that is higher than the expected therapeutic dose and is toxic when given over a long period of time. Physical examinations and laboratory tests are performed to determine which organs are affected and whether the drug has the potential to cause cancer (carcinogenic).

Animal studies enable scientists to develop a therapeutic index for the drug. A therapeutic index is the ratio between the median lethal dose and the median effective dose. It tells a practitioner the safe dose to give for the therapeutic effect to be achieved.

Some drugs have a narrow margin of safety and require that the blood plasma levels be frequently monitored to assure that the drug stays within the therapeutic range. Drugs that have a wide margin of safety don't require that the plasma levels be monitored. Digitalis (digoxin) is an example of a drug that has a narrow margin of safety and requires frequent monitoring of plasma levels.

Scientists also learn how the drug is absorbed, distributed, metabolized, and excreted once it is administered to the animals. This helps scientists predict how the drug will react when administered to humans.

Tests are also conducted in laboratory test tubes that can determine the metabolism of the drug in humans, which may be different from animals. These are called in vitro studies. Once animal studies are successfully completed, the drug is ready for human trials during which human subjects are given the drug. There are three phases of human trial.

PHASE I: INITIAL PHARMACOLOGICAL EVALUATION

In Phase I, drug trials, the drug is given to a small number of healthy volunteers to determine safe dosage levels. The purpose is to document the dose level at which signs of toxicity first appear in humans, determine a safe tolerated dose, and determine the pharmacokinetics of the drug. Pharmacokinetics will be discussed in Chapter 2. Volunteers who give consent to participate are monitored closely during this phase. Permission must be obtained from the FDA to conduct Phase I clinical trials.

PHASE II: LIMITED CONTROLLED EVALUATION

The purpose of Phase II evaluation is to monitor drug effectiveness and any side effects. Individuals with the targeted disease participate in this phase of drug trials. For example, antihypertensive (blood pressure lowering) drugs will be administered to patients who have hypertension (high blood pressure) to determine the drug's effectiveness or optimal dose response range and for side effects. The number of participants is larger than Phase I trials but usually does not exceed 100 persons and every effort is made to use only people who have no other disorders or diseases.

PHASE III: EXTENDED CLINICAL EVALUATION

Phase III drug trials include many physicians and large groups of participants. When enough information has been collected to justify continued use of the drug, a New Drug Application (NDA) is submitted to the FDA. Usually, more than 4 years has passed between the drug's selection and the filing of the NDA.

Phase IV studies are also called post-marketing follow-up. They are voluntarily conducted by pharmaceutical companies. These studies continue after the FDA has approved the drug and often include populations such as pregnant women, children, and the elderly. Manufacturers can find low-level side effects or can find that a drug is toxic and must be removed from market. The FDA continues to monitor new drugs even after they are marketed.

Drugs also undergo tests to determine the possible effects on a fetus. As a result of these tests, drugs are classified using the following Pregnancy Categories.

Category A

Adequate and well-controlled studies indicate no risk to the fetus in the first trimester of pregnancy or later.

Category B

Animal reproduction studies indicate no risk to the fetus, however there are no well-controlled studies in pregnant women.

Category C

Animal reproduction studies have reported adverse effects on the fetus, however there are no well-controlled studies in humans but potential benefits may indicate use of the drug in pregnant women despite potential risks.

Category D

Positive human fetal risk has been reported from investigational or marketing experience, or human studies. Considering potential benefit versus risk may, in selected cases, warrant the use of these drugs in pregnant women.

Category X

Fetal abnormalities reported and positive evidence of fetal risk in humans is available from animal and/or human studies. The risks involved clearly outweigh the potential benefits. These drugs should not be used in pregnant women.

Locating Drug Information

Before administering a drug to a patient (see Chapter 4), healthcare providers need to know the following information about the drug:

• Generic and trade name: The generic name is the official name of the drug while the trade name is the drug's brand name.

• Clinical uses and indications for use: Describes the purpose of the drug and when the drug is to be given to a patient.

• Mechanism of action: Describes how the drug works.

• Adverse and side effects and toxicity: Identifies the effects the drug has other than the therapeutic effect.

• Signs and symptoms to monitor: Identifies the patient's physiological response that must be evaluated after the drug is administered.

• What to teach the patient: Specifies instructions that must be given to the patient before and after the drug is administered.

This information is available in product inserts, various drug handbooks for nurses, and in computerized pharmacology databases and in the following:

• American Hospital Formulary Service (AHFS) Drug Information: Published by the American Society of Hospital Pharmacists, Inc. and contains an overview of every drug.

• United States Pharmacopeia Dispensing Information: Published by the U.S. Pharmacopeial Convention and highlights clinical information, which is the same as the drug inserts found in packages of drugs.

• Physician's Desk Reference (PDR): Published by Medical Economics with the financial support of the pharmaceutical industry and contains the same information as found in the drug inserts.

• Physician's GenRx published by Mosby and includes comprehensive drug information product identification charts and product ratings by the Food and Drug Administration. It also contains cost comparisons between drugs.

• Handbook of Nonprescription Drugs: Published by the American Pharmaceutical Association and contains comprehensive information on over-the-counter drugs including the primary minor illnesses the drug is used to treat.

• Medline Plus (http://www.nlm.nih.gov/medlineplus/druginformation.html): An online database produced by the U. S. National Library of Medicine and the National Institutes of Health and contains information about prescription and over-the-counter drugs and devices as well as warnings and drug recall information.

Drug Orders

A drug order, also called a medical prescription, is an instruction from a provider to give a patient medication. Providers such as a physician, dentist, podiatrist, advanced practice nurse (in most states), and other authorized licensed healthcare providers can write a drug order. Physician assistants can also write a drug order but require the co-signature of a physician.

All drug orders are written on a prescription pad or on an order sheet if written in a healthcare institution. Sometimes orders are written into a computerized drug order system. A verbal drug order is sometimes given but must be followed up with a written drug order within 24 hours.

Drug orders are written using the abbreviations shown in Table 1-1 and must contain:

• Date and time the order (prescription) was issued.

• Name of drug and whether or not a generic form of the drug can be substituted for a brand-name drug.

• Route of administration.

• Frequency and duration of administration.

• Special instructions such as withholding or adjusting dosage based on nursing assessment, laboratory results, or drug effectiveness.

Signature of the prescriber.

Signature of the healthcare providers who took the order and transcribed it.

Table 1-1. Commonly used abbreviations for drug orders.

Direction

L (in circle)

Left

R (in a circle)

Right

Dose

aa

Of each

c

With

DS

Double strength

elix.

Elixir

fl or fld.

Fluid

gtt

Drop

NS or N/S

Normal saline

q.s.

A sufficient amount/ as much as needed/ quantity sufficient

s

Without

ssor ss

One half

SR

Sustained release

XL

Long acting

XR

Extended release

Form

amp

ampule

aq

water

c

Cup

cap or caps

Capsule

EC

Enteric coated

mix

Mixture

sol or soln

Solution

supp

Suppository

Table 1-1. (continued)

susp

Suspension

syp or syr

Syrup

tab

Tablet

Tr or tinct

Tincture

ung. or oint

Ointment

Method

gt or GT

Gastrostomy tube

I.D.

Intradermal

I.M.

Intramuscular

I.V.

Intravenous

IVPB

Intravenous piggyback

IVSS

Intravenous soluset

KVO

Keep vein open (a vey slow infusion rate)

NGT

Nasogastric tube

n.p.o

Nothing by mouth

Per

Through or by

Per os or p.o.

By or through mouth

p.r.

By rectum

s.c or S.C. or s.q.*

Subcutaneous

sl or SL

Sublingual

S&S

Swish and swallow

vag

Vaginally

Part

A.D. or AD*

Right ear

A.S. or AS*

Left ear

A.U. or AU*

Both ears

OD*

Right eye

os*

Mouth

OS*

Left eye

Table 1-1. (continued)

OU*

Both eyes

Rect*

Rectum

Time

a

Before

ad.lib

As desired

b.i.d. or bid

Twice a day

d.c. or D/C

Discontinue

h or hr

Hour

h.s.

At bed time

min

Minute

o.d. or OD

Once a day

P

After

px.

After meals

p.r.n.

When necessary

q.

Every, each

q.a.m.

Every morning

q.d. or qd*

Every day or once a day

q.h. or qh

Every hour

q2h, q4h

Every two hours, every four hours

qhs or q.h.s.*

Every night at bedtime

q.i.d. or qid

Four times a day

q.o.d. or qod*

Every other day

s.o.s

Once if necessary

stat or STAT

Immediately or at once

t.i.d. or tid

Three times a day

t.i.w.*

Three times a week

*The Joint Commission for Accreditation of Hospitals Organization (JCAHO) has recommended that these abbreviations not be used to decrease the chance of errors. However, some hospitals and providers continue to use them when writing medications orders.

*The Joint Commission for Accreditation of Hospitals Organization (JCAHO) has recommended that these abbreviations not be used to decrease the chance of errors. However, some hospitals and providers continue to use them when writing medications orders.

TYPES OF DRUG ORDERS

There are four types of drug orders. These are:

Routine orders: This is an ongoing order given for a specific number of doses or number of days.

Example: 1/31/05 7:30 p.m. Lasix (furosemide) 40 mg., PO, qd (signature)

This is an order to give 40 milligrams of Lasix by mouth once a day. Once a day medications are generally given around 9 a.m. or 10 a.m. based on the healthcare institution or patient choice if at home. Lasix is a diuretic.

One-time order: This is a single dose given at a particular time.

Example: Demerol 50 mg with Vistaril 25 mg IM at 10 a.m. or 2 h before call to the OR.

This is an order to give Demerol (meperidine) 50 milligrams with Vistaril (hydroxyzine) 25 milligrams intramuscularly at 10 a.m. or one hour before call to the operating room.

PRN: This is an order to give a medication if specific criteria exist, such as a headache, fever, or pain and at the patient's request.

Example: Advil 600 mg po q 6 h prm for mild to moderate knee pain.

This is an order to give Advil (ibuprofen) 600 milligrams by mouth every six hours as needed for mild to moderate knee pain.

STAT: This is a single dose order to give at once or immediately

Example: Give Benadryl 50 mg. po Stat.

This is an order to give Benadryl (dyphenhydramine) 50 milligrams by mouth immediately.

There are also protocols for administering medications. This is a set of criteria that indicates under what conditions a drug may be given. There are two types of protocols: standing orders or flow diagrams (algorithms). Standing orders are an officially accepted sets of orders to be applied by nurses, physician assistants, and paramedics in the care of patients with certain conditions or under certain circumstances. For example, if a patient is not breathing and has no heartbeat, an algorithm has been developed to administer different medications such as epinephrine and other cardiac stimulants to resuscitate the individual. Other standing orders include orders for Tylenol (acetaminophen) 600 milligrams q 4 h by mouth or per rectum for a temperature > 101.4°F.

The "Five Rights" of Drug Administration

There are five traditional right actions that should be followed when giving medication. These are to determine the right patient, right drug, right dose, right time, and right route. Five additional rights include the right assessment, documentation, education, evaluation, and the right to refuse.

RIGHT PATIENT

The right patient means that the healthcare provider gives the drug to the right patient. Each time a drug is administered, the healthcare provider must verify who the patient is by the patient's identification bracelet. This is the preferred method as opposed to identifying a patient by asking his or her name. Some patients will answer "yes" to any name and two patients can have similar-sounding names or the same name. Some patients are not mentally alert and do not remember their name. Again, check the patient's identification every time medication is administered.

RIGHT DRUG

Healthcare providers must be sure that the drug is the correct medication for the patient. This too leads to errors. Healthcare providers ask: Was this the drug prescribed on the medication order? Is the medication order legible and complete? Why is the patient receiving this medication? Is the medication consistent with the patient's condition? Does the patient have any food or drug allergies?

Providers check the expiration date and return the medication to the pharmacy if it has expired. If the medication is used past the expiration date, the effect on the patient can be unpredictable.

Healthcare providers check the medication label three times before administering the drug. First, when they take the medication from the shelf or drawer. Next, the label should be checked before pouring the drug, and third it is checked after pouring the drug before throwing away the drug packaging.

RIGHT DOSE

The dose on the medication order must be within recommended guidelines. The healthcare provider should have a general idea of the dose before performing any drug calculations. If the calculated dose varies too much from this estimated dose, check with a pharmacist or another appropriate healthcare provider. Some drug calculations should always be checked by two individuals if the calculation is complicated or the drug has the potential to be harmful if the dose is too large or too small. Medications that are wrapped and labeled or pre-filled for the exact dose are preferred and can reduce errors.

Healthcare providers should also make sure they use the proper system of measurement when calculating a dose (see Chapter 4 Principles of Medication Administration).

RIGHT TIME

Is it the correct time to administer the drug? The time is specified in the drug order and may be given a half hour before or after the stated time depending on the policy of the hospital or healthcare facility. How often a drug is given is dependent on the half life of the drug. A drug's half life is the amount of time for /2 of the drug to be eliminated from the body. A drug with a short half life must be administered more frequently than a drug with a long half-life in order to maintain a therapeutic level of the drug in plasma.

The use of military time can avoid a.m. and p.m. errors.

Check if the patient is scheduled for diagnostic or other procedures that might interfere with administration of medications. Check if the patient should receive the medication even if they are scheduled to be NPO (nothing by mouth).

Healthcare providers should also make sure that medication is given in coordination with meals. Some drugs must be given with meals while other drugs are given a specific period before or after a meal.

Where possible, the medication schedule is adjusted to conform to the patient's lifestyle, which may differ from the normal schedule. For example, Digoxin might be scheduled for 10 a.m. to conform to hospital policy, but the patient can take Digoxin any time in the morning. This becomes important once the patient is discharged and takes medication at home.

RIGHT ROUTE

The healthcare provider determines the proper routine to administer the drug so the patient's body properly absorbs it. Here are the common routes:

• Oral (by mouth): liquid, elixir, suspension, pill, tablet, and capsule

• Sublingual (under tongue): pill, tablet, and capsule

• Buccal (between gum and cheek): pill, tablet, and capsule

• Topical (applied to skin): cream, ointment, and patch

• Inhalation (aerosol sprays): liquid

• Instillation (nose, eye, ear): liquid, cream, and ointment

• Insertion (rectal, vaginal): suppository

• Intradermal (beneath skin): injection

• Subcutaneous (beneath skin): injection

• Intramuscular (in muscle): injection

• Intravenous (in vein): injection

• Nasogastric and gastronomy tubes: liquid

• Transdermal: patches

Make sure that the patient can swallow if the route of the medication is by mouth and stay with the patient until the medication is swallowed. Enteric coated or time-release drugs should not crushed or mixed. Caution should be used when administering intravenous medications because the body quickly absorbs these drugs. Therefore, healthcare providers need to know expected side effects, effects that occur when the drug is first given, effects the drug has during its therapeutic peak, and duration of the drug's action. Caution should be used when administering any medication via this route.

Self-administration of medication (SAM) is the normal practice for patients in the home and workplace. This method is also used in some acute and long-term care institutional settings. In these settings the nurse gives the patient a packet of medications with instructions that are kept at the bedside. The patient takes the medication according to the instructions and advises the nurse when he or she has done so. This practice help patients learn how to manage the medications and prepares them for discharge and use of these medications in the home. This method is often used with oncology (cancer) patients and maternity patients.

Patient controlled analgesia (PCA) is a common method of administering intravenous pain medication for many patients. This will be discussed further in a subsequent chapter.

RIGHT TO REFUSE MEDICATION

A mentally competent patient has the right to refuse medication. Refusal is documented on the patient record. Patients should be advised of the consequences of the refusal to take the medication such as a worsening of the condition. As a general rule, every effort is made to encourage the patient to take the medication. However, no one should physically force a patient to take medication.

RIGHT TO EDUCATION

The patient has the right to be told about the medication that is about to be administered. The patient is told:

• The name of the medication

• Why the medication is given

• What the medication looks like

• How much of the medication to take

• When to take the medication

• When not to take the medication

• What are the side effects, adverse effects, and toxic effects

This information is discussed in the best way the patient can understand. Healthcare providers should avoid speaking in medical terminology and, instead, use common words and expressions that are familiar to the patient—and always in the language that the patient speaks.

The patient provides feedback that he or she understands everything about the medication. It is common for the healthcare provider to ask the patient to tell in his or her own words what was told to them about the medication.

The patient is also shown how to keep track of multiple medications. Typically, the patient is encouraged to keep a list of medications. The list should have the name of the medication, dose, time the medication is to be taken and the name and phone number of the prescriber who ordered the medication.

Summary

Pharmacology is the study of drug effects on living tissue and how drugs cure, prevent, or manage diseases. Drugs are derived from plants, animals, minerals, and are synthesized in the laboratory. Each drug has three names. These are the chemical name, the generic name that is considered the official name for the drug, and the brand name, which is used by the manufacturer to market the drug.

There are two general classifications of drugs: prescription and over-the-counter drugs. Prescription drugs are also known as legend drugs and must be prescribed by an authorized healthcare provider. Over-the-counter drugs can be purchased with or without a prescription.

Drugs have three effects: these are the therapeutic effect to fight or prevent a disease; a side effect that isn't harmful; and an adverse effect that is harmful to a varying degree. Some drugs can also cause an allergic response in some patients. Healthcare providers must know about these effects before administering the medication to the patient. Furthermore, the patient must be informed of these effects.

Before a drug is manufactured and released for public use, it must undergo a series of tests that begin with animal studies and follows through to clinical studies on humans. Animal studies determine the therapeutic index for the drug. Clinical studies determine the therapeutic effect, adverse effect, and side effects the drug has on humans.

A drug is prescribed to a patient by writing a drug order or medical prescription. A drug order specifies, among other things, the name of the drug, the dose, route of administration, and frequency. Only an authorized healthcare provider can order drugs. There are four types of drug orders. These are routine orders, one-time orders, PRN orders, and STAT orders. There are also standing orders or protocols.

There are five right actions to take when giving medications. These are to give the right patient the right drug, in the right dose, at the right time, by the right route. Patients also have the right to refuse medication and the right to education about the medication.

With this overview of pharmacology under your belt, let's take a closer look at how drugs work by exploring the principles of drug action and drug interactions in the next chapter.

Quiz

1. A brand name of a drug is

(a) the non-trademarked name given by the original drug manufacturer.

(b) the trademarked name given by the drug manufacturer.

(c) the official nonproprietary name for the drug.

(d) the universally accepted name.

2. Schedule I controlled substances

(a) cannot be prescribed.

(b) can be prescribed only by a physician.

(c) can be purchased over-the-counter.

(d) are approved for medical use.

3. The 1938 Food, Drug and Cosmetic Act

(a) established categories of drugs.

(b) standardized labeling for drugs.

(c) established who could prescribe drugs.

(d) requires drug manufacturers to prove that their drugs are safe.

4. Herbals are tested and regulated by the Food and Drug Administration.

5. All drug side effects are harmful.

6. Drugs come from

7. P.O. in a drug order means by rectum.

8. A drug order that requires the drug to be given immediately is called a

(d) standing order.

9. A patient does not have the right to refuse medication.

10. The number of times a drug is given to a patient can be determined by the half-life of the drug.

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