An adverse drug reaction (ADR) is an injury caused by taking medication. ADRs can range from mild to severe or lethal. Common ADRs to antibiotics include diarrhea, disruption of intestinal flora, and yeast infections. Diagnosing ADRs considers rechallenge, reporting to drug monitoring programs, and postmarketing surveillance to identify low-incidence ADRs. Treatment involves modifying or stopping the drug, switching to an alternative, or preventing interactions.

1. ADVERSE
DRUG
REACTION
SAAJIDA
SULTAANA
MAHUSOOK

2. • Adverse drug reaction
• An adverse drug reaction (ADR) is an injury caused by
taking medication. It may occur following a single dose or prolonged
administration of a drug or result from the combination of two or
more drugs.
• "It is an appreciably harmful or unpleasant reaction, resulting from
an intervention related to the use of a medicinal product, which
predicts hazard from future administration and warrants prevention
or specific treatment, or alteration of the dosage regimen, or
withdrawal of the product."
• Some antibacterials have been associated with a range of adverse
effects.

3. • Side-effects range from mild to very serious depending on the
antibiotics used, the microbial organisms targeted, and the individual
patient.
• Safety profiles of newer drugs are often not as well established as
for those that have a long history of use. Adverse effects range from
fever and nausea to major allergic reactions, including
photodermatitis and anaphylaxis.
• Common side-effects include diarrhea, resulting from disruption of
the species composition in the intestinal flora, resulting, for example,
in overgrowth of pathogenic bacteria, such as Clostridium difficile.
• Antibacterials can also affect the vaginal flora, and may lead to
overgrowth of yeast species of the genus Candida in the vulvo-
vaginal area.
• Other side-effects can result from interaction with other drugs, such
as elevated risk of tendon damage from administration of a
quinolone antibiotic with a systemic corticosteroid.

4. Severity Description Example
Mild No antidote or treatment is required;
hospitalization is not prolonged.
Antihistamines (some): Drowsiness
Opioids: Constipation
Moderate A change in treatment (eg, modified dosage,
addition of a drug), but not necessarily
discontinuation of the drug, is required;
hospitalization may be prolonged, or specific
treatment may be required.
Hormonal contraceptives: Venous
thrombosis
NSAIDs: Hypertension and edema
Severe An ADR is potentially life threatening and
requires discontinuation of the drug and specific
treatment of the ADR.
ACE inhibitors: Angioedema
Phenothiazines: Abnormal heart rhythm
Lethal An ADR directly or indirectly contributes to a
patient’s death.
Acetaminophen overdosage: Liver
failure
Anticoagulants: Hemorrhage
Classification

5. Etiology
• Most adverse drug reactions are dose-related; others are allergic or
idiosyncratic.
• Dose-related ADRs are usually predictable; ADRs unrelated to dose
are usually unpredictable.
• Dose-related ADRs are particularly a concern when drugs have a
narrow therapeutic index (eg, hemorrhage with oral anticoagulants).
ADRs may result from decreased drug clearance in patients with
impaired renal or hepatic function or from drug-drug interactions.
• Allergic ADRs are not dose-related and require prior exposure. Allergies
develop when a drug acts as an antigen or allergen. After a patient is
sensitized, subsequent exposure to the drug produces one of several
different types of allergic reaction. Clinical history and appropriate skin
tests can sometimes help predict allergic ADRs.
• Idiosyncratic ADRs are unexpected ADRs that are not dose-related or
allergic. They occur in a small percentage of patients given a drug.
Idiosyncrasy is an imprecise term that has been defined as a
genetically determined abnormal response to a drug, but not all
idiosyncratic reactions have a pharmacogenetic cause. The term may
become obsolete as specific mechanisms of ADRs become known.

6. Signs and Symptoms
• Adverse drug reactions are usually classified as mild, moderate,
severe, or lethal Severe or lethal ADRs may be specifically
mentioned in black box warnings in the physician prescribing
information provided by the manufacturer.
• Symptoms and signs may manifest soon after the first dose or only
after chronic use. They may obviously result from drug use or be too
subtle to identify as drug-related. In the elderly, subtle ADRs can
cause functional deterioration, changes in mental status, failure to
thrive, loss of appetite, confusion, and depression.
• Allergic ADRs typically occur soon after a drug is taken but generally
do not occur after the first dose; typically, they occur when the drug
is given after an initial exposure. Symptoms include itching, rash,
fixed-drug eruption, upper or lower airway edema with difficulty
breathing, and hypotension.
• Idiosyncratic ADRs can produce almost any symptom or sign and
usually cannot be predicted.

7. Diagnosis
• Consideration of rechallenge
• Reporting of suspected ADRs to MedWatch
• Symptoms that occur soon after a drug is taken are often easily connected with
use of a drug. However, diagnosing symptoms due to chronic drug use requires
a significant level of suspicion and is often complicated. Stopping a drug is
sometimes necessary but is difficult if the drug is essential and does not have an
acceptable substitute. When proof of the relationship between drug and
symptoms is important, rechallenge should be considered, except in the case of
serious allergic reactions.
• Physicians should report most suspected adverse drug reactions to MedWatch
(the Food and Drug Administration's [FDA’s] ADR monitoring program), which is
an early alert system. Only through such reporting can unexpected ADRs be
identified and investigated. MedWatch also monitors changes in the nature and
frequency of ADRs. The FDA's Adverse Event Reporting System (FAERS) is a
search tool that improves access to data about adverse drug reactions.
• The incidence of severe or fatal adverse drug reactions is very low (typically < 1
in 1000) and may not be apparent during clinical trials, which are typically not
powered to detect low-incidence ADRs. Thus, these ADRs may not be detected
until after a drug is released to the general public and is in widespread use.
Clinicians should not assume that because a drug is on the market that all ADRs
are known. Postmarketing surveillance is extremely important for tracking low-
incidence ADRs.

8. Treatment
• Modification of dosage
• Discontinuation of drug
• Switching to a different drug
• For dose-related adverse drug reactions, modifying the dose or
eliminating or reducing precipitating factors may suffice.
Prevention
• Prevention of adverse drug reactions requires familiarity with the
drug and potential reactions to it.
• Computer-based analysis should be used to check for potential drug
interactions; analysis should be repeated whenever drugs are
changed or added. If patients develop nonspecific symptoms, ADRs
should always be considered before beginning symptomatic
treatment.

9. Reference
• https://www.ncbi.nlm.nih.gov/pubmed/11072960
• https://www.msdmanuals.com/en-in/professional/clinical-
pharmacology/adverse-drug-reactions/adverse-drug-reactions
Thank You