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 Indications, Dosage, Storage, Stability - Phentolamine Mesylate
Regitine Indications, Dosage, Storage, Stability - Phentolamine Mesylate
INDICATIONS
Phentolamine Mesylate for Injection is indicated for the prevention
or control of hypertensive
episodes that may occur in a patient
with pheochromocytoma as a result of stress
or manipulation
during preoperative preparation
and surgical excision.
Phentolamine Mesylate for Injection is indicated for the prevention
or treatment of dermal
necrosis and sloughing
following intravenous
administration or extravasation
of norepinephrine.
Phentolamine Mesylate for Injection is also indicated for the diagnosis
of pheochromocytoma
by the phentolamine blocking
test.
DOSAGE AND ADMINISTRATION
The reconstituted solution
should be used upon preparation
and should not be stored.
1. Prevention or control
of hypertensive
episodes in the patient with pheochromocytoma.
For preoperative reduction
of elevated blood pressure,
5 mg of phentolamine mesylate
(1 mg for children) is injected
intravenously or intramuscularly 1 or 2 hours before surgery, and
repeated if necessary.
During surgery, phentolamine mesylate (5 mg
for adults, 1 mg for children)
is administered intravenously as indicated, to help prevent or control
paroxysms of hypertension, tachycardia, respiratory depression,
convulsions, or other effects of epinephrine
intoxication. (Postoperatively, norepinephrine may be given to control
the hypotension
that commonly follows complete removal of a pheochromocytoma.)
2. Prevention or treatment
of dermal necrosis
and sloughing following
intravenous administration
or extravasation
of norepinephrine.
For Prevention: 10 mg
of phentolamine mesylate is added to each liter of solution
containing norepinephrine. The pressor
effect of norepinephrine
is not affected.
For Treatment: 5 to 10 mg
of phentolamine mesylate in 10 mL of saline is injected
into the area of extravasation
within 12 hours.
3. Diagnosis of pheochromocytoma
- phentolamine blocking
test.
The test is most reliable
in detecting pheochromocytoma
in patients with sustained hypertension
and least reliable in those with paroxysmal hypertension. False-positive
tests may occur in patients with hypertension without pheochromocytoma.
a. Intravenous
Preparation: The CONTRAINDICATIONS
,
WARNINGS, and PRECAUTIONS
sections should be reviewed. Sedatives, analgesics, and all other
medications except those that might be deemed essential
(such as digitalis
and insulin) are withheld for at least 24 hours, and preferably
48 to 72 hours, prior to the test. Anti-hypertensive drugs are withheld
until blood pressure returns
to the untreated, hypertensive
level. This test is not
preformed on a patient
who is normotensive.
Procedure: The patient
is kept at rest in a supine
position throughout
the test, preferably in a quiet, darkened room. Injection of phentolamine
is delayed until blood
pressure is stabilized,
as evidenced by blood
pressure readings taken every 10 minutes for at least 30 minutes.
Five milligrams of phentolamine mesylate is dissolved in 1 mL of
Sterile Water for Injection. The dose
for adults is 5 mg; for children, 1 mg.
The syringe needle
is inserted into the vein, and injection
is delayed until pressor
response to venipuncture
has subsided.
Phentolamine is injected
rapidly. Blood pressure
is recorded immediately after injection, at 30-second intervals
for the first 3 minutes, and at 60- second intervals for the next
7 minutes.
Interpretation: A positive
response, suggestive
of pheochromocytoma, is indicated when the blood
pressure is reduced
more than 35 mm Hg
systolic and 25 mm Hg
diastolic. A typical
positive response
is a reduction in
pressure of 60 mm Hg
systolic and 25 mm
Hg diastolic. Usually, maximal
effect is evident within
2 minutes after injection. A return to preinjection pressure commonly
occurs within 15 to 30 minutes but may occur more rapidly.
If blood pressure
decreases to a dangerous level, the patient
should be treated as outlined under OVERDOSAGE.
A positive response
should always be confirmed by other diagnostic
procedures, preferably by measurement of urinary catecholamines
or their metabolites.
A negative response
is indicated when the blood
pressure is elevated,
unchanged, or reduced less than 35 mm
Hg systolic
and 25 mm Hg
diastolic after injection
of phentolamine. A negative
response to this test
does not exclude the diagnosis
of pheochromocytoma, especially in patients with paroxysmal hypertension
in whom the incidence
of false- negative
responses is high.
b. Intramuscular
If the intramuscular
test for pheochromocytorna
is preferred, preparation is the same as for the intravenous
test. Five milligrams of phentolamine mesylate is then dissolved
in 1 mL of Sterile Water for Injection. The dose for adults is 5
mg intramuscularly; for children,
3 mg. Blood pressure is recorded every 5 minutes for 30 to 45 minutes
following injection. A positive response
is indicated when the blood
pressure is reduced
35 mm Hg systolic and
25 mm Hg
diastolic, or more, within 20 minutes following injection.
Note: Parenteral drug
products should be inspected visually for particulate matter
and discoloration prior to administration, whenever solution and
container permit.
HOW SUPPLIED
Phentolamine Mesylate for Injection USP, 5 mg, for intramuscular
or intravenous use, is supplied in a 2 mL vial
and individually boxed. NDC 55390-113-01.
The reconstituted solution
should be used upon preparation
and should not be stored.
Store at controlled room
temperature, 15° to 30° C (59° to 86° F).
CAUTION: Federal wlaw
prohibits dispensing without prescription.
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