Adverse drug reactions Flashcards
What is an adverse drug reaction?
“An unintended or unexpected effect on animals, human beings, or the environment, including injury, sensitivity reactions or lack of efficacy associated with the clinical use of a veterinary medicine (which includes pharmaceutical, biological and pesticide products).”
What is a suspected adverse drug reaction?
Where the causality of an adverse drug reaction is uncertain
What is an adverse event?
“An untoward occurrence that may be present during treatment with a veterinary medicine but which do not necessarily have a causal relationship with this treatment”
List some things to consider regarding adverse drug reactions
All therapeutic drugs have a toxic/lethal dose
ADR may exacerbate existing conditions or manifest as another disease
Some ADR take a long time to become evident, which may be more difficult to recognise
ADRs may only occur with certain physiological states (e.g. pregnancy)
What is pharmacogenomics?
The study of individual differences or certain genotypes in the way the body handles drugs (e.g. MDR1, multidrug resistance gene)
What is the genetic basis of the MDR1 gene mutation?
4 base pair delation mutation in the Multi Drug Resistance gene (associated with multiple drug sensitivity)
Which breeds of dog are more likely to be affected by the MDR1 gene mutation?
75% of collies in Australia
Shetland sheepdogs
Old English sheepdogs
German Shepherds
Long-haired Whippets
(>10 purebreds)
Variety of mixed-breed dogs
What are the effects of the MDR1 gene mutation?
Alteration in the blood brain barrier alowing increased penetration of a number of drugs
Relatively reduced rate of drug elimination
Results in elevated plasma drug levels and increased tendency for toxicity
Which drugs are known to cause problems in dogs with MDR1 mutation?
Acepromazine
Butorphanol
Cyclosporin
Digoxin
Doxorubicin (antineoplastic)
Ivermectin
Loperamide
Vinblastine (antineoplastic)
Vincristine (antineoplastic
How are adverse drug reactions categoried?
Type A, B, C, D, E, F
What is a type A drug reaction?
Augmented reaction
Expected but exaggerated pharmacological or toxic responses to a drug (including normal side effects).
Predictable, dose-dependent and usually avoidable
What is the difference between primary and secondary responses in a Type A reaction
Primary: exaggeration of the inteded response (absolute or relative overdose)
Secondary: affecting an organ other than the target (side effect)
Give examples of Type A ADRs
Tachycardia with salbutamol
Water retention with glucocorticoid administration
Hypotension after acepromazine
Decreased tear production (keratoconjunctivitis sicca) with sulphonamides
(Any side effect)
What is meant by tolerance?
Increasing doses of a drug required to produce the same effect. May be pharmacokinetic, pharmacodynamic, physiological or behavioural
What is meant by tachyphylaxis?
A rapid decrease in response rate following repeated administration of a drug over a short interval.
Not dose-dependent, but rate-sensitive, and usually resolves after a short witholding period
