Ch.'s 7-8 & 11-13, Lehne's Pharmacology (Comp. Pharm Final)
Fundamentals of Pharmacology: Adverse
Drug Events and Individual Variation
I. Adverse Drug Reactions (ADRs)
An adverse drug reaction (ADR) is defined as:
Any noxious, unintended, and undesired effect that occurs at normal drug doses.
ADRs encompass a wide range of responses, from mild discomfort to life-
threatening conditions.
Types of Adverse Drug Reactions
Allergic Reaction:
An immune response triggered by re-exposure to a drug that
previously sensitized the immune system.
o The intensity of an allergic reaction is based on the degree of immune
system sensitization, not the drug dosage.
Carcinogenic Effect:
The ability of certain medications and environmental chemicals to
cause cancers.
o The carcinogenic potential of a new drug is usually unknown at the
time of its release.
Hepatotoxic Drugs:
Drugs that, after metabolism in the liver, are converted to toxic
products that can injure liver cells.
o Drugs are the most common cause of acute liver failure.
o Hepatotoxicity is the most common reason for removing drugs from
the market.
Iatrogenic Disease:
, A disease that occurs as a result of medical care or treatment,
including diseases produced by drugs.
Idiosyncratic Effect:
An uncommon drug response resulting from a genetic predisposition.
o Example: Red blood cell hemolysis in individuals with glucose-6-
phosphate dehydrogenase (G6PD) deficiency upon taking
sulfonamides or aspirin.
Medication Error:
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.
o A major cause of morbidity and mortality.
Organ-Specific Toxicity:
Many drugs exhibit toxicity towards specific organs.
o Special attention should be paid to drugs causing liver injury
(hepatotoxic) and those altering ***cardiac function (QT interval
drugs)***.
Physical Dependence:
A state in which the body has adapted to drug exposure, leading to an
abstinence syndrome if drug use is discontinued.
o Develops with long-term use of opioids, alcohol, barbiturates, and
amphetamines.
o Patients should be warned against abrupt discontinuation without
consulting a healthcare professional.
QT Interval Drugs:
Medications with the ability to prolong the QT interval on the ECG,
increasing the risk of serious dysrhythmias.
o The QT interval measures the time required for the ventricles to
repolarize after each contraction.
Fundamentals of Pharmacology: Adverse
Drug Events and Individual Variation
I. Adverse Drug Reactions (ADRs)
An adverse drug reaction (ADR) is defined as:
Any noxious, unintended, and undesired effect that occurs at normal drug doses.
ADRs encompass a wide range of responses, from mild discomfort to life-
threatening conditions.
Types of Adverse Drug Reactions
Allergic Reaction:
An immune response triggered by re-exposure to a drug that
previously sensitized the immune system.
o The intensity of an allergic reaction is based on the degree of immune
system sensitization, not the drug dosage.
Carcinogenic Effect:
The ability of certain medications and environmental chemicals to
cause cancers.
o The carcinogenic potential of a new drug is usually unknown at the
time of its release.
Hepatotoxic Drugs:
Drugs that, after metabolism in the liver, are converted to toxic
products that can injure liver cells.
o Drugs are the most common cause of acute liver failure.
o Hepatotoxicity is the most common reason for removing drugs from
the market.
Iatrogenic Disease:
, A disease that occurs as a result of medical care or treatment,
including diseases produced by drugs.
Idiosyncratic Effect:
An uncommon drug response resulting from a genetic predisposition.
o Example: Red blood cell hemolysis in individuals with glucose-6-
phosphate dehydrogenase (G6PD) deficiency upon taking
sulfonamides or aspirin.
Medication Error:
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.
o A major cause of morbidity and mortality.
Organ-Specific Toxicity:
Many drugs exhibit toxicity towards specific organs.
o Special attention should be paid to drugs causing liver injury
(hepatotoxic) and those altering ***cardiac function (QT interval
drugs)***.
Physical Dependence:
A state in which the body has adapted to drug exposure, leading to an
abstinence syndrome if drug use is discontinued.
o Develops with long-term use of opioids, alcohol, barbiturates, and
amphetamines.
o Patients should be warned against abrupt discontinuation without
consulting a healthcare professional.
QT Interval Drugs:
Medications with the ability to prolong the QT interval on the ECG,
increasing the risk of serious dysrhythmias.
o The QT interval measures the time required for the ventricles to
repolarize after each contraction.
