AM - Side effects/toxicity Flashcards
What antimicrobial type most commonly causes allergic reactions?
B-Lactams
How common is penicillin hypersensitivity?
True penicillin hypersensitivity is rare but alot of patients with other side effects are wrongly labelled as allergic
Are penicillin alleric patients allergic to any other antimicrobials?
Around 10% of the truly penicillin alleric patients are also alleric to cephalosporins
What are the 2 types of antimicrobial allergy?
Immediate hypersensitivity
Delayed Hypersensitivity
Whats the most extreme form of immediate hypersensitivity?
Anaphylactic shock usually following parenteral administration of an antibiotic
What mediates immmediate allergic reactions?
IgE
What are the symptoms of immediate hypersensitivity?
- Itching
- Urticaria
- Nausea
- Vomiting
- Wheezing
- Shock
- Laryngeal Oedema
What symptom of immediate hypersensitivity is most commonly fatal?
The laryngeal Oedema is often fatal if the airway isnt cleared.
How long does a delayed hypersensitivity reactions take?
Hours or Days to occur
What mediates delayed hypersensitivity reactions?
- Immune complexes
- or Cell mediated
What are the symptoms of delayed hypersensitivity?
Drug rashes
Drug Fever
Serum Sickness
Erythema Nodosum
Whats erythema nodosum?
Red lumps on the skin
Describe the rashes in a delayed hypersensitivity reaction?
Rashes are maculopapular
i.e. flat red area of skin covered in small bumps
Whats stevens-johnson syndrome?
A form of delayed hypersensitivity where the skin & mucous membranes are both involved.
Its associated with sulphonamides
Whats the common gastrointestinal side effects of antimicrobials?
Nausea
Vomiting
What is CDAD?
Clostridium Difficile Associated Diarrhoea
Whats CDI?
Clostridium Difficile Infection (specifically infection of a dangerous strain no the normal commensal in the gut)
Whats an EIA?
An Enzyme Immunoassay
What happens to C. Diff. when during antibiotic use?
It overgrows normal flora in the gut and produces toxins
What does C. Diff growth cause during antibiotic use?
Anything from mild CDAD or CDI to life threatening pseudomembranous colitis.
How do we check fo a CDI?
Use an EIA to check the stool for toxins
How do we treat a CDI?
Oral Vancomycin or metronidazole
IF possible stop all other antibiotic treatment
How do we stop spores of the dangerous C Diff strains spreading?
- Isolating patients with CDI
- Hand Washing with soap (resistant to alcohol gel)
What antimicrobials cause thrush?
Broad Spectrum penicillins & cephalosporins
What is Thrush?
ORal and/or Vaginal Candidiasis
fungal infection of candida yeast
How do antimicrobials cause thrush?
Certain antimicrobials cause thrush by suppressing normal flora leading to overgrowth of yeast candida albicans
What kind of liver toxicity can be caused by antimicrobials?
Varies from transient elevation of liver enzymes al the way to severe hepatitis
In what patients are liver toxicity side effects most common?
Pregnant patients
Or those with pre-existing liver disease
Name some drugs associated with liver toxicicity:
Tetracycline
Rifampicin
Flucloxacillin
Isoniazid (anti-TB)
Who does nephrotoxiicty effect most?
People with pre-exisiting renal disease
Why do we monitor the levels of aminoglycosides & vancomycin in the blood?
Because they can cause renal toxicity
What drugs cause ototoxicity?
Aminoglycosides
Vancomycin
What drug can cause optic nerve damage?
Ethambutol an anti-TB drug can damage the optic nerve
What do we monitor during ethambutol treatment?
Durin ethambutol treatment we monitor optic nerve function
What drugs cause encephalopathy & convulsions?
High dose Penicillin
High dose Cephalosporin
Acyclovir (an anti-viral)
How do we alter the drug if the pateint has renal impairment?
MAy have to reduce the dose proportionally to impairment to avoid toxicity (particularly encephalopathy & convulsion)
What drugs can cause peripheral neuropathy?
Metronidazole
Nitrofurantoin
How does Isoniazid cause peripheral neuropathy?
By competetive inhibition wiht pyridoxine (Vitamin B6)
In what ways can AMs affect cause marow depression?
Selective Depression of one cell line
Unselective depression of all bone marrow elements (pancytopenia)
Example of AM that suppresses marrow?
Linezolid (an anti-MRSA agent) can cause low platelet counts
What haematological side effect can co-trimoxazole cause?
Inhibits folic acid synthesis
- > a folate deiciency
- > megaloblastic anaemia
What antiviral blood levels must be monitored?
Zidovudine for HIV
Ganciclovir for CMV
