Small Animal Clinical Pharmacology - CYF MEDICAL DISTRIBUTION

GLUCOCORTICOSTEROIDS
● Other potential adverse effects include:
– hypertension
– Na + and water retention (insignificant with most
synthetic glucocorticosteroids)
– peripheral edema (rare)
– gastric ulceration and hemorrhage (usually only
when there is another concurrent ulcerogenic
stimulus such as NSAID administration, altered
gut blood flow)
– pancreatitis (degree to which glucocorticosteroids
used at anti-inflammatory doses are a risk factor
in pancreatitis is controversial)
– osteoporosis (more an issue in humans than
dogs and cats)
– myopathy (rare)
– behavioral changes
– neuropathy (rare)
– cataract
– glaucoma.
● Adverse effects are less common in cats than dogs
given chronic glucocorticoid therapy and are usually
restricted to the development of poly dipsia, polyuria
(although usually not to the degree experienced by
dogs), polyphagia and weight gain.
Contraindications and precautions
● There is a range of contraindications for glucocorticoid
administration, which are largely situations
in which the immunomodulatory or metabolic
effects of these drugs would amplify an existing
pathology in an individual patient, for example those
with:
– infectious disease (particularly bacterial, viral or
fungal)
– diabetes mellitus
– liver disease (unless specifically indicated to treat
the pathology present)
– protein-losing nephropathy (unless specifically
indicated to treat the pathology present; however,
there is no good evidence that glucocorticosteroid
treatment reduces protein loss in immunemediated
glomerulonephropathy).
● Corticosteroids may induce abortion or congenital
defects if administered during pregnancy.
● Corticosteroids may inhibit growth if given to immature
animals.
● Wound or fracture healing may be inhibited by
glucocorticoids.
● Topical ophthalmic corticosteroid should not be
instilled into an eye with infection, glaucoma or
corneal ulceration because of the risk of inducing
corneal perforation and delaying repair, and the possibility
of secondary infection.
● Owners should be advised to wear gloves when
applying topical corticosteroids.
Known drug interactions
A range of drug interactions is reported for
glucocorticoids.
● Increased insulin requirements with concurrent glucocorticoid
therapy.
● Increased metabolism of glucocorticoids by phenytoin,
phenobarbital, rifampicin (rifampin).
● Reduced blood levels of salicylates with glucocorticoid
therapy.
● Hypokalemia when glucocorticoids are given concurrently
with amphotericin B or potassiumdepleting
diuretics (e.g. furosemide); when these
agents are used together with digitalis therapy, there
is an increased risk of digitalis toxicity in the presence
of hypokalemia.
● Concurrent administration of glucocorticoids and
ciclosporin leads to reduced hepatic metabolism
of each drug, with elevated blood levels of both
agents.
● Glucocorticoids reduce hepatic metabolism of
cyclophosphamide.
● Erythromycin reduces hepatic metabolism of
methylprednisolone.
● Concurrent administration of drugs known to induce
gastrointestinal ulceration (e.g. nonsteroidal antiinflammatories)
with glucocorticoids increases the
risk of such ulceration, which may also occur more
readily in animals given corticosteroids for spinal
cord trauma.
● Estrogens may potentiate the effects of
glucocorticoids.
● Glucocorticoids at immunosuppressive doses should
be administered with care to myasthenic animals as
they may lead to an exacerbation of weakness, the
mechanism of which has been poorly defined. Myasthenic
dogs should initially be given glucocorticoids
at anti-inflammatory doses, and these may be
increased to immunosuppressive levels over a 1–2
week period. Patients should be carefully monitored
over this time. As a general rule, the more severe the
weakness, the lower the dose of glucocorticoids that
should be used.
● Animals receiving immunosuppressive doses of glucocorticoids
may make a diminished response to vaccines
and should not be given live viral vaccines.
However, one early study of dogs administered distemper
virus vaccine after a 21-day course of prednisolone
(1 mg/kg or 10 mg/kg PO) revealed adequate
serum neutralizing antibody and protection from
challenge with virulent virus.
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