Small Animal Clinical Pharmacology - CYF MEDICAL DISTRIBUTION

CHAPTER 3 ADVERSE DRUG REACTIONS
Undesirable
clinical
phenomenon
Anticipated
drug effect not
observed
Adverse Event (AE)
Associated with drug treatment?
No
AE
Yes
Serious?
Unexpected death? Serious morbidity? Teratogenic effects? Animal
welfare compromised? Effect om human leading to death or requiring
medical treatment?
Yes
No
Suspected serious
adverse drug reaction
Suspected adverse
drug reaction
Investigation (veterinarian/regulator):
chance, bias, confounding, causation
Casualty components:
Temporality? Biological plausibility? Consistency? Dose-response?
Dechallenge? Rechallenge? Alternatives? Strength of association?
A
Probable
B
Possible
O
Unassessable
N
Unlikely
Fig. 3.1 Adverse event classification.
Type E (end of treatment) ADRs occur when drug
treatment is terminated suddenly. Examples include
withdrawal seizures on terminating anticonvulsant
therapy and adrenocortical insufficiency subsequent to
cessation of chronic administration of glucocorticoids.
Type F (failure of treatment) ADRs can be particularly
informative if thoroughly investigated. There can
be a multitude of reasons for treatment failure and a
direct drug-related cause is unusual.
Table 3.1 provides a summary of many factors to be
considered when faced with antibacterial drug failure.
A similar list can readily be prepared for other drug
categories.
INCIDENCE OF ADVERSE
DRUG REACTIONS
The incidence of ADRs in veterinary medicine is difficult
to evaluate. In human medicine it has been estimated
that 3–5% of all hospitalized patients are admitted
because of an ADR. Some studies give a wide variety of
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