A1,
A2,
B,
C1,
C2,
D,
E,
F,
G-H,
I-K,
L,
M,
N,
O,
P1,
P2,
Q-R,
S,
T,
U-V,
W-Z
Regitine Warnings, Precautions, Pregnancy, Nursing, Abuse - Phentolamine Mesylate
Regitine Warnings, Precautions, Pregnancy, Nursing, Abuse - Phentolamine Mesylate
WARNINGS
Myocardial infarction, cerebrovascular
spasm, and cerebrovascular
occlusion have been reported to occur following the administration
of phentolamine, usually in association
with marked hypotensive
episodes.
For screening tests in patients with hypertension, the generally
available urinary assay of catecholamines or other biochemical
assays have largely replaced the phentolamine and other pharmacological
tests for reasons of accuracy and safety. None of the chemical
or pharmacological tests is infallible in the diagnosis
of pheochromocytoma. The phentolamine blocking
test is not the procedure
of choice and should be reserved for cases in which additional confirmatory
evidence is necessary
and the relative risks involved in conducting the test
have been considered.
PRECAUTIONS
General
Tachycardia and cardiac
arrhythmias may occur with the use of phentolamine or other alpha-adrenergic
blocking agents. When
possible, administration of cardiac
glycosides should be deferred until cardiac
rhythm returns to normal.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Long-term carcinogenicity studies, mutagenicity studies, and fertility
studies have not been conducted with phentolamine.
Pregnancy
Teratogenic Effects - Pregnancy Category C: Administration
of phentolamine to pregnant
rats and mice at oral doses
24 to 30 times the usual daily human
dose (based on a 60 kg
human) resulted in slightly decreased growth
and slight skeletal
immaturity of the fetuses. Immaturity was manifested by increased
incidence of incomplete
or unossified calcanei and phalangeal
nuclei of the hind limb
and of incompletely ossified sternebrae. At oral
doses 60 times the usual daily human
dose (based on a 60 kg
human), a slightly lower rate
of implantation
was found in the rat. Phentolamine did not affect
embryonic or fetal
development in the
rabbit at oral doses 20
times the usual daily human
dose (based on a 60 kg
human). No teratogenic or embryotoxic effects were observed in the
rat, mouse, or rabbit studies.
There are no adequate and well-controlled studies in pregnant
women. Phentolamine should be used during pregnancy only if the
potential benefit
justifies the potential
risk to the fetus.
Nursing Mothers
It is not known whether this drug
is excreted in human milk.
Because many drugs are excreted in human
milk and because of the
potential for serious
adverse reactions in nursing
infants from phentolamine, a decision should be made whether to
discontinue nursing
or to discontinue the drug, taking into account the importance of
the drug to the mother.
Pediatric Use
See DOSAGE AND ADMINISTRATION.
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