Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Chapter 7 Adverse Drug Reactions and Medication Errors

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.

Chapter 7

Adverse Drug Reactions and Medication Errors

2Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.

Two Related Issues of Drug Safety

Adverse drug reactions (ADRs) Also known as adverse drug events (ADEs)

Medication errors


Adverse Drug Reactions

Defined by the World Heath Organization Any noxious, unintended, and undesired effect

that occurs at normal drug doses Excludes excessive dosages Can range from annoying to life-threatening



Scope of the problem Mild reactions

• Drowsiness, nausea, itching, and rash Severe reactions (potentially fatal)

Respiratory depression, neutropenia, hepatocellular injury, anaphylaxis, hemorrhage

Most common in the elderly and very young Risk increased by severe illness Possibly 110,000 deaths a year due to ADRs


Terms Related to Adverse Drug Reactions

Side effect Toxicity Allergic reaction Idiosyncratic effect Iatrogenic disease Physical dependence Carcinogenic effect Teratogenic effect


Terms Related to Adverse Drug Reactions cont’d

Organ-specific toxicity Kidneys Lungs Inner ear Heart

QT interval Liver



Side effect A nearly unavoidable secondary drug effect

produced at therapeutic doses May develop soon after drug is initiated or not until

drug has been taken for weeks or months Toxicity

Formal definition: adverse drug reaction caused by excessive dosing

May occur even with normal dosing• Neutropenia (risk for infection) and anticancer

medications



Allergic reaction Immune response Determined primarily by the degree of

sensitization of the immune system, not by drug dosage

Patient’s sensitivity to a drug can change over time.

Very few drugs cause severe allergic reaction.• Penicillins are the most common.• Allergies may also be induced by sulfonamides

(diuretics, antibiotics, and oral hypoglycemic agents).



Idiosyncratic effect An uncommon drug response resulting from a

genetic predisposition Succinylcholine-induced paralysis

• Usually brief• May last for hours in genetically predisposed patient



Iatrogenic disease iatros = a Greek word meaning “physician” genic = a combining form meaning “to produce” iatrogenic = literally, “a disease produced by a

physician,” also used to refer to a disease produced by drugs (eg, drugs for antipsychotic disorders can cause Parkinson’s-like symptoms)

Sometimes also called drug-induced disease Essentially identical to naturally occurring

pathology



Physical dependence Develops during long-term use of certain drugs

(opioids, alcohol, barbiturates, and amphetamines) A state in which the body has adapted to drug

exposure in such a way that• An abstinence syndrome will result if drug use is

discontinued Important to warn patients against abrupt

discontinuation of any medication without first consulting a knowledgeable health professional



Carcinogenic effect Only a few therapeutic agents are carcinogenic. Several drugs used to treat cancer are among

those with the greatest carcinogenic potential. Evaluating drugs is difficult; it may take decades

for evidence of carcinogenesis after exposure. An example is diethylstilbestrol (DES).

Teratogenic effect Drug-induced birth defect More discussion of this topic in Chapter 9



Organ-specific toxicity Many drugs are toxic to specific organs. Common examples include

• Kidneys: amphotericin B (antifungal)• Heart: doxorubicin (anticancer)• Lungs: amiodarone (antidysrhythmic)• Inner ear: aminoglycoside (antibiotic)


Organ-Specific Toxicity

Hepatotoxic drugs QT interval drugs


Hepatotoxic Drugs

Leading cause of liver failure in the United States More than 50 drugs are known to be hepatotoxic. As some drugs undergo metabolism, they are

converted to toxic products that can injure liver cells. Combining hepatotoxic drugs may increase the risk

for liver damage—for example, acetaminophen and alcohol.

Monitor aspartate aminotransferase (AST) and alanine aminotransferase (ALT) for liver injury.

Watch for signs of liver injury; educate patient: Jaundice, dark urine, light-colored stools, nausea, vomiting,

malaise, abdominal discomfort, loss of appetite



QT Interval Drugs: More Than 100 Are Known

QT interval: measure of the time required for the ventricles to repolarize after each contraction

QT drugs: the ability of some drugs to prolong the QT interval on electrocardiography (ECG)

Creates serious risk of life-threatening dysrhythmias Examples: torsades de pointes, V-fib

Minimizing the risk Patients at higher risk include women, the elderly, and

patients with bradycardia, congestive heart failure (CHF), congenital QT prolongation, low potassium, and low magnesium.

Do not use two QT drugs concurrently.



Identifying Adverse Drug Reactions

Can be very difficult to determine whether a specific drug is responsible for an observed adverse event

Other factors to consider Underlying illness Other drugs


Identifying Adverse Drug Reactions

Did symptoms appear shortly after the drug was first used?

Did symptoms abate when the drug was discontinued?

Did symptoms reappear when the drug was reinstituted?

Is the illness itself sufficient to explain the event?

Are other drugs in the regimen sufficient to explain the event?


Adverse Reactions to New Drugs

50% of all new drugs have serious ADRs that are not revealed during Phase II and Phase III trials.

Be alert for unusual responses when giving new drugs.

Drugs that you suspect of causing a previously unknown adverse effect should be reported to MedWatch: the FDA Medical Products Reporting

Program


Ways to Minimize Adverse Drug Reactions

Responsibility for reducing ADRs lies with everyone associated with drug production and usage Prescriber: select the least harmful drug. Balance

potential risks versus probable benefit. Nurse: evaluate patient for ADRs and educate

patients and families on how to minimize harm. Patients and families: watch for signs an ADR may

be developing and notify health care provider.


Ways to Minimize Adverse Drug Reactions

Anticipation of ADRs can help minimize them. Target evaluation of the function of any at-risk

organs Important sites of toxicity

• Liver: signs of jaundice; monitor liver function tests (LFTs)

• Kidney: routine urinalysis and serum creatinine (periodic creatinine clearance)

• Bone marrow: periodic blood cell counts Patients with chronic disorders are especially

vulnerable to ADRs.


Boxed Warnings

Black box warnings Strongest safety warning a drug can carry

and still remain on the market Concise summary of the adverse effects of

concern Text is presented inside a box with a heavy

black border.


Medication Errors

Major cause of morbidity and mortality Documented in two landmark reports from the

Institute of Medicine: To Err Is Human—1999 Preventing Medication Errors—2006

It is estimated that medication errors Injure 1.5 million people per year Kill 7000 people per year


Medication Errors

Defined by the National Coordinating Council for Medication Error Reporting and Prevention (NCCMERP) as “. . .any preventable event that may cause or lead to

inappropriate medication use or patient harm, while the medication is in the control of the healthcare professional, patient, or consumer. Such events may be related to professional practice, healthcare products, procedures, and systems, including prescribing; order communication, product labeling, packaging and nomenclature, compounding, dispensing; distribution, administration; education, monitoring; and use”


Medication Errors

Risk for error in hospitals is high because each medication order is processed by several people. The nurse is the last person in this sequence. Thus, the nurse is the last line of defense against

mistakes. This places a heavy responsibility on the nurse for

ensuring patient safety.


Types of Medication Errors

Fatal medication errors Overdose: 36.4% Wrong drug: 16.2% Wrong route: 9.5%



Causes of Medication Errors

90% of all errors are due to Human factors Communication mistakes Name confusion




Ways to Reduce Medication Errors

Help and encourage patients and their families to be active, informed members of the health care team.

Create an institutional culture dedicated to safety.

Give health care providers the tools and information they need to prescribe, dispense, and administer drugs as safely as possible.

Institute safety checklists for high-alert drugs. About 20 drugs cause 80% of medication error-

related deaths.


Ways to Reduce Medication Errors

Replace handwritten medication orders with a computerized order entry system.

Have a senior clinical pharmacist accompany physicians on rounds.

Use a bar-code system. Do not use error-prone abbreviations. See Table 7-7.


Ways to Report Medication Errors

Medication Errors Reporting (MER) program Reporting is confidential. Reporting can be done by phone, fax, or Internet.

Program encourages all health care providers, including pharmacists, nurses, physicians, and students, to report errors.

www.usp.org/hqi/patientSafety/mer/ All information is forwarded to the Food and

Drug Administration (FDA), the Institute for Safe Medication Practices (ISMP), and the product manufacturer

http://www.usp.org/hqi/patientSafety/mer/

Documents

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Chapter 7 Adverse Drug Reactions and Medication Errors