drug interactions. –adverse drug effects –hypersensitivity –anaphylactic reactions
TRANSCRIPT
DRUG INTERACTIONS
DRUG INTERACTIONS
– Adverse drug effects
– Hypersensitivity
– Anaphylactic reactions
Adverse drug effects
• An unwanted or harmful reaction experienced following the administration of a drug or combination of drugs under normal conditions of use and suspected to be related to the drug
Onset Severity Type
Classification
Onset of event:• Acute
• within 60 minutes• Sub-acute
• 1 to 24 hours• Latent
• > 2 days
Classification
Severity of reaction:•Mild
• bothersome but requires no change in therapy
•Moderate• requires change in therapy, additional
treatment, hospitalization
• Severe• disabling or life-threatening
Classification - Severity
– Result in death
– Life-threatening
– Require hospitalization
– Prolong hospitalization
– Cause disability
– Cause congenital anomalies
– Require intervention to prevent permanent injury
Classification - Severity
•Type A• extension of pharmacologic effect• often predictable and dose dependent• responsible for at least two-thirds of
ADRs• propranolol is given for tachycardia to
reduce heart rate.It can cause heart block due to excessively slowing the heart
Classification
•Type B
• idiosyncratic or immunologic reactions
• rare and unpredictable
• e.g., chloramphenicol and aplastic anemia
Classification
•Type C
• associated with long-term use
• involves dose accumulation
• e.g., antimalarials and ocular toxicity
Classification
•Type D
• delayed effects (dose independent)
• Carcinogenicity (e.g., immunosuppressants)
• Teratogenicity (e.g., fetal hydantoin syndrome)
Classification
Types of allergic reactions• Type I • Type II• Type III• Type IV
Classification- Drug Hypersensitivity
Understanding hypersensitivity
• Our immune system mediates this
• Immune system has lots of cells
• Mast cells are responsible of type 1
• Antibodies cause type 11 and 111
• T cells cause type 1V
Examples
• Type 1-anaphylaxis to drugs
• Type 11-drug induced hemolysis
• Type 111-serum sickness syndrome
Drug-Induced Hemolytic Anemia
• This is where certain antibiotics can absorb to the proteins on RBC membranes
• Examples: penicillin, streptomycin
• Sometimes antibodies cause lysis and thus progressive anemia
• When drug is withdrawn the hemolytic anemia disappears
Serum sickness syndrome
• reaction that develops when antigen is intravenously administered resulting in formation of large amounts antigen-antibody complexes and the deposition in tissue
Risk factors for Drug Allergy
• Frequent exposure to the drug
• Large doses of the drug
• Drug given by injection rather than pill
• Family tendency to develop allergies and asthma.
Anaphylactic Reaction
• Life threatening
• Almost all anaphylactic reactions occur within 4 hours of the first dose of the drug. Most occur within 1 hour of taking the drug, and many occur within minutes or even seconds.
Symptoms of anaphylactic shock
• Skin reaction - Hives, redness/flushing, sense of warmth, itching
• Difficulty breathing - Chest tightness, wheezing, throat tightness
• Fainting - Light-headness or loss of consciousness due to drastic decrease in blood pressure ("shock")
• Rapid or irregular heart beat• Swelling of face, tongue, lips, throat, joints, hands,
or feet
The causative antigens causing anaphylaxis
• Blood products
• ß-lactam antibiotics• X-ray contrast agent• Other drugs
Prophylaxis of anaphylaxis
• Routine skin testing before giving drugs • If X ray contrast is to be used in a patient, the
patient should be pretreated with a steroid if there is a history of allergies
Thank you…