Proam insert 006 (page 1)

ProAmatine®
WARNING: Because ProAmatine® can cause marked elevation of supine blood pressure,
it should be used in patients whose lives are considerably impaired despite standard
clinical care. The indication for use of ProAmatine® in the treatment of symptomatic
orthostatic hypotension is based primarily on a change in a surrogate marker of
effectiveness, an increase in systolic blood pressure measured one minute after
standing, a surrogate marker considered likely to correspond to a clinical benefit. At
present, however, clinical benefits of ProAmatine®, principally improved ability to carry
out activities of daily living, have not been verified.
DESCRIPTION
Name: ProAmatine® (midodrine hydrochloride) Tablets
Dosage Form: 2.5-mg, 5-mg and 10-mg tablets for oral administration
Active Ingredient: Midodrine hydrochloride, 2.5 mg, 5 mg and 10 mg
Inactive Ingredients: Colloidal Silicone Dioxide NF, Corn Starch NF, FD&C Blue No. 2 Lake (10-
mg tablets), FD&C Yellow No. 6 Lake (5-mg tablet), Magnesium Stearate NF, Microcrystalline
Cellulose NF, Talc USP
Pharmacological Classification: Vasopressor/Antihypotensive
Chemical Names (USAN: Midodrine Hydrochloride): (1) Acetamide, 2-amino-N-[2-(2,5-
dimethoxyphenyl)-2-hydroxyethyl]-monohydrochloride, (±)-;
(2) (±)-2-amino-N-(ß-hydroxy-2,5-dimethoxyphenethyl)acetamide monohydrochloride
BAN, INN, JAN: Midodrine
Structural formula:
Molecular formula: C12H18N2O4HCl; Molecular Weight: 290.7
Organoleptic Properties: Odorless, white, crystalline powder
Solubility: Water:
pKa: 7.8 (0.3% aqueous solution) pH: 3.5 to 5.5 (5% aqueous solution)
Melting Range: 200 to 203°C
CLINICAL PHARMACOLOGY
Mechanism of Action: ProAmatine® forms an active metabolite, desglymidodrine, that is an
alpha1-agonist, and exerts its actions via activation of the alpha-adrenergic receptors of the
arteriolar and venous vasculature, producing an increase in vascular tone and elevation of
blood pressure. Desglymidodrine does not stimulate cardiac beta-adrenergic receptors.
Desglymidodrine diffuses poorly across the blood-brain barrier, and is therefore not associated
with effects on the central nervous system.
Administration of ProAmatine® results in a rise in standing, sitting, and supine systolic and
diastolic blood pressure in patients with orthostatic hypotension of various etiologies. Standing
systolic blood pressure is elevated by approximately 15 to 30 mmHg at 1 hour after a 10-mg
dose of midodrine, with some effect persisting for 2 to 3 hours. ProAmatine® has no clinically
significant effect on standing or supine pulse rates in patients with autonomic failure.
Pharmacokinetics: ProAmatine® is a prodrug, i.e., the therapeutic effect of orally administered
midodrine is due to the major metabolite desglymidodrine, formed by deglycination of
midodrine. After oral administration, ProAmatine® is rapidly absorbed. The plasma levels of the
prodrug peak after about half an hour, and decline with a half-life of approximately 25 minutes,
while the metabolite reaches peak blood concentrations about 1 to 2 hours after a dose of
midodrine and has a half-life of about 3 to 4 hours. The absolute bioavailability of midodrine
(measured as desglymidodrine) is 93%. The bioavailability of desglymidodrine is not affected by
food. Approximately the same amount of desglymidodrine is formed after intravenous and oral
administration of midodrine. Neither midodrine nor desglymidodrine is bound to plasma proteins
to any significant extent.
Metabolism and Excretion: Thorough metabolic studies have not been conducted, but it
appears that deglycination of midodrine to desglymidodrine takes place in many tissues, and
both compounds are metabolized in part by the liver. Neither midodrine nor desglymidodrine is a
substrate for monoamine oxidase.
Renal elimination of midodrine is insignificant. The renal clearance of desglymidodrine is of the
order of 385 mL/minute, most, about 80%, by active renal secretion. The actual mechanism of
active secretion has not been studied, but it is possible that it occurs by the base-secreting
pathway responsible for the secretion of several other drugs that are bases (see also Potential
for Drug Interactions).
Clinical Studies
Midodrine has been studied in 3 principal controlled trials, one of 3-weeks duration and 2 of 1 to
2 days duration. All studies were randomized, double-blind and parallel-design trials in patients
with orthostatic hypotension of any etiology and supine-to-standing fall of systolic blood pressure
of at least 15 mmHg accompanied by at least moderate dizziness/lightheadedness. Patients with
pre-existing sustained supine hypertension above 180/110 mmHg were routinely excluded. In a
3-week study in 170 patients, most previously untreated with midodrine, the midodrine-treated
patients (10 mg t.i.d., with the last dose not later than 6 P.M.) had significantly higher (by about
20 mmHg) 1-minute standing systolic pressure 1 hour after dosing (blood pressures were not
measured at other times) for all 3 weeks. After week 1, midodrine-treated patients had small
improvements in dizziness/lightheadedness/unsteadiness scores and global evaluations, but these
effects were made difficult to interpret by a high early drop-out rate (about 25% vs 5% on
placebo). Supine and sitting blood pressure rose 16/8 and 20/10 mmHg, respectively, on average.
In a 2-day study, after open-label midodrine, known midodrine responders received midodrine
10 mg or placebo at 0, 3, and 6 hours. One-minute standing systolic blood pressures were
increased 1 hour after each dose by about 15 mmHg and 3 hours after each dose by about
12mmHg; 3-minute standing pressures were increased also at 1, but not 3, hours after dosing.
There were increases in standing time seen intermittently 1 hour after dosing, but not at 3 hours.
In a 1-day, dose-response trial, single doses of 0, 2.5, 10, and 20 mg of midodrine were given
to 25 patients. The 10- and 20-mg doses produced increases in standing 1- minute systolic
pressure of about 30 mmHg at 1 hour; the increase was sustained in part for 2 hours after
10 mg and 4 hours after 20 mg. Supine systolic pressure was ≥200 mmHg in 22% of patients
on 10mg and 45% of patients on 20 mg; elevated pressures often lasted 6 hours or more.
Special Populations
A study with 16 patients undergoing hemodialysis demonstrated that ProAmatine® is removed
by dialysis.
INDICATIONS AND USAGE
ProAmatine® is indicated for the treatment of symptomatic orthostatic hypotension (OH).
Because ProAmatine® can cause marked elevation of supine blood pressure (BP>200 mmHg
systolic), it should be used in patients whose lives are considerably impaired despite standard
clinical care, including non-pharmacologic treatment (such as support stockings), fluid
expansion, and lifestyle alterations. The indication is based on ProAmatine®’s effect on
increases in 1-minute standing systolic blood pressure, a surrogate marker considered likely to
correspond to a clinical benefit. At present, however, clinical benefits of ProAmatine®,
principally improved abitlity to perform life activities, have not been established. Further clinical
trials are underway to verify and describe the clinical benefits of ProAmatine®.
After initiation of treatment, ProAmatine® should be continued only for patients who report
significant symptomatic improvement.
CONTRAINDICATIONS
ProAmatine® is contraindicated in patients with severe organic heart disease, acute renal
disease, urinary retention, pheochromocytoma or thyrotoxicosis. ProAmatine® should not be
used in patients with persistent and excessive supine hypertension.
WARNINGS
Supine Hypertension: The most potentially serious adverse reaction associated with
ProAmatine® therapy is marked elevation of supine arterial blood pressure (supine
hypertension). Systolic pressure of about 200 mmHg were seen overall in about 13.4% of
patients given 10 mg of ProAmatine®. Systolic elevations of this degree were most likely to
be observed in patients with relatively elevated pre-treatment systolic blood pressures
(mean 170 mmHg). There is no experience in patients with initial supine systolic pressure
above 180 mmHg, as those patients were excluded from the clinical trials. Use of
ProAmatine® in such patients is not recommended. Sitting blood pressures were also
elevated by ProAmatine® therapy. It is essential to monitor supine and sitting blood
pressures in patients maintained on ProAmatine®.
PRECAUTIONS
General: The potential for supine and sitting hypertension should be evaluated at the beginning
of ProAmatine® therapy. Supine hypertension can often be controlled by preventing the patient
from becoming fully supine, i.e., sleeping with the head of the bed elevated. The patient should
be cautioned to report symptoms of supine hypertension immediately. Symptoms may include
cardiac awareness, pounding in the ears, headache, blurred vision, etc. The patient should be
advised to discontinue the medication immediately if supine hypertension persists.
Blood pressure should be monitored carefully when ProAmatine® is used concomitantly with
other agents that cause vasoconstriction, such as phenylephrine, ephedrine, dihydroergotamine,
phenylpropanolamine, or pseudoephedrine.
A slight slowing of the heart rate may occur after administration of ProAmatine®, primarily due
to vagal reflex. Caution should be exercised when ProAmatine® is used concomitantly with
cardiac glycosides (such as digitalis), psychopharmacologic agents, beta blockers or other
agents that directly or indirectly reduce heart rate. Patients who experience any signs or
symptoms suggesting bradycardia (pulse slowing, increased dizziness, syncope, cardiac
awareness) should be advised to discontinue ProAmatine® and should be re-evaluated.
ProAmatine® should be used cautiously in patients with urinary retention problems, as
desglymidodrine acts on the alpha-adrenergic receptors of the bladder neck.
ProAmatine® should be used with caution in orthostatic hypotensive patients who are also
diabetic, as well as those with a history of visual problems who are also taking fludrocortisone
acetate, which is known to cause an increase in intraocular pressure and glaucoma.
ProAmatine® use has not been studied in patients with renal impairment. Because
desglymidodrine is eliminated via the kidneys, and higher blood levels would be expected in
such patients, ProAmatine® should be used with caution in patients with renal impairment, with
a starting dose of 2.5 mg (see DOSAGE AND ADMINISTRATION). Renal function should be
assessed prior to initial use of ProAmatine®.
ProAmatine® use has not been studied in patients with hepatic impairment. ProAmatine®
should be used with caution in patients with hepatic impairment, as the liver has a role in the
metabolism of midodrine.
Information for Patients: Patients should be told that certain agents in over-the-counter
products, such as cold remedies and diet aids, can elevate blood pressure, and therefore,
should be used cautiously with ProAmatine®, as they may enhance or potentiate the pressor
effects of ProAmatine® (see Drug Interactions). Patients should also be made aware of the
possibility of supine hypertension. They should be told to avoid taking their dose if they are to
be supine for any length of time, i.e., they should take their last daily dose of ProAmatine® 3 to
4 hours before bedtime to minimize nighttime supine hypertension.
Laboratory Tests: Since desglymidodrine is eliminated by the kidneys and the liver has a role in
its metabolism, evaluation of the patient should include assessment of renal and hepatic
function prior to initiating therapy and subsequently, as appropriate.
Drug Interactions: When administered concomitantly with ProAmatine®, cardiac glycosides
may enhance or precipitate bradycardia, A.V. block or arrhythmia.
The use of drugs that stimulate alpha-adrenergic receptors (e.g., phenylephrine,
pseudoephedrine, ephedrine, phenylpropanolamine or dihydroergotamine) may enhance or
potentiate the pressor effects of ProAmatine®. Therefore, caution should be used when
ProAmatine® is administered concomitantly with agents that cause vasoconstriction.
ProAmatine® has been used in patients concomitantly treated with salt-retaining steroid therapy
(i.e., fludrocortisone acetate), with or without salt supplementation. The potential for supine
hypertension should be carefully monitored in these patients and may be minimized by either
reducing the dose of fludrocortisone acetate or decreasing the salt intake prior to initiation of
treatment with ProAmatine®. Alpha-adrenergic blocking agents, such as prazosin, terazosin,
and doxazosin, can antagonize the effects of ProAmatine®.
Potential for Drug Interaction: It appears possible, although there is no supporting
experimental evidence, that the high renal clearance of desyglymidodrine (a base) is due to active
tubular secretion by the base-secreting system also responsible for the secretion of such drugs
as metformin, cimetidine, ranitidine, procainamide, triamterene, flecainide, and quinidine. Thus
there may be a potential for drug-drug interactions with these drugs.
Carcinogenesis, Mutagenesis, Impairment of Fertility: Long-term studies have been
conducted in rats and mice at dosages 3 to 4 times the maximum recommended daily
human dose on a mg/m2 basis, with no indication of carcinogenic effects related to
ProAmatine®. Studies investigating the mutagenic potential of ProAmatine® revealed no
evidence of mutagenicity. Other than the dominant lethal assay in male mice, where no
impairment of fertility was observed, there have been no studies on the effects of ProAmatine®
on fertility.
Pregnancy: Pregnancy Category C. ProAmatine® increased the rate of embryo resorption,
reduced fetal body weight in rats and rabbits, and decreased fetal survival in rabbits when given
in doses 13 (rat) and 7 (rabbit) times the maximum human dose based on body surface area
(mg/m2). There are no adequate and well-controlled studies in pregnant women. ProAmatine®
should be used during pregnancy only if the potential benefit justifies the potential risk to the
fetus. No teratogenic effects have been observed in studies in rats and rabbits.
Nursing Mothers: It is not known whether this drug is excreted in human milk. Because many
drugs are excreted in human milk, caution should be exercised when ProAmatine® is
administered to a nursing woman.
Pediatric Use: Safety and effectiveness in pediatric patients have not been established.
ADVERSE REACTIONS
The most frequent adverse reactions seen in controlled trials were supine and sitting
hypertension; paresthesia and pruritus, mainly of the scalp; goosebumps; chills; urinary urge;
urinary retention and urinary frequency.
The frequency of these events in a 3-week placebo-controlled trial is shown in the following table:
Adverse Events
Midodrine
# of reports
% of patients
# of reports
% of patients
1 Includes hyperesthesia and scalp paresthesia2 Includes dysuria (1), increased urinary frequency (2), impaired urination (1), urinary retention 3 Includes scalp pruritus
4 Includes patients who experienced an increase in supine hypertension
5 Includes abdominal pain and pain increase
Less frequent adverse reactions were headache; feeling of pressure/fullness in the head;
vasodilation/flushing face; confusion/thinking abnormality; dry mouth; nervousness/anxiety and
rash. Other adverse reactions that occurred rarely were visual field defect; dizziness; skin
hyperesthesia; insomnia; somnolence; erythema multiforme; canker sore; dry skin; dysuria;
impaired urination; asthenia; backache; pyrosis; nausea; gastrointestinal distress; flatulence and
leg cramps.
The most potentially serious adverse reaction associated with ProAmatine® therapy is supine
hypertension. The feelings of paresthesia, pruritus, piloerection and chills are pilomotor
reactions associated with the action of midodrine on the alpha-adrenergic receptors of the hair
follicles. Feelings of urinary urgency, retention and frequency are associated with the action of
midodrine on the alpha-receptors of the bladder neck.
OVERDOSAGE
Symptoms of overdose could include hypertension, piloerection (goosebumps), a sensation of
coldness and urinary retention. There are 2 reported cases of overdosage with ProAmatine®,
both in young males. One patient ingested ProAmatine® drops, 250 mg, experienced systolic
blood pressure greater than 200 mmHg, was treated with an IV injection of 20 mg of
phentolamine, and was discharged the same night without any complaints. The other patient
ingested 205 mg of ProAmatine® (41 5-mg tablets), and was found lethargic and unable to talk,
unresponsive to voice but responsive to painful stimuli, hypertensive and bradycardic. Gastric
lavage was performed, and the patient recovered fully by the next day without sequelae.
The single doses that would be associated with symptoms of overdosage or would be
potentially life-threatening are unknown. The oral LD50 is approximately 30 to 50 mg/kg in rats,
675 mg/kg in mice, and 125 to 160 mg/kg in dogs.
Desglymidodrine is dialyzable.
Recommended general treatment, based on the pharmacology of the drug, includes inducedemesis and administration of alpha-sympatholytic drugs (e.g., phentolamine).
DOSAGE AND ADMINISTRATION
The recommended dose of ProAmatine® is 10 mg, 3 times daily. Dosing should take place
during the daytime hours when the patient needs to be upright, pursuing the activities of daily
living. A suggested dosing schedule of approximately 4-hour intervals is as follows: shortly before,
or upon arising in the morning, midday and late afternoon (not later than 6 P.M.). Doses may be
given in 3-hour intervals, if required, to control symptoms, but not more frequently. Single
doses as high as 20 mg have been given to patients, but severe and persistent systolic supine
hypertension occurs at a high rate (about 45%) at this dose. In order to reduce the potential for
supine hypertension during sleep, ProAmatine® should not be given after the evening meal or
less than 4 hours before bedtime. Total daily doses greater than 30 mg have been tolerated by
some patients, but their safety and usefulness have not been studied systematically or
established. Because of the risk of supine hypertension, ProAmatine® should be continued only
in patients who appear to attain symptomatic improvement during initial treatment.
The supine and standing blood pressure should be monitored regulary, and the administration
of ProAmatine® should be stopped if supine blood pressure increases excessively.
Because desglymidodrine is excreted renally, dosing in patients with abnormal renal function
should be cautious; although this has not been systematically studied, it is recommended that
treatment of these patients be initiated using 2.5-mg doses.
Dosing in children has not been adequately studied.
Blood levels of midodrine and desglymidodrine were similar when comparing levels in patients
65 or older vs. younger than 65 and when comparing males vs. females, suggesting dose
modifications for these groups are not necessary.
HOW SUPPLIED
ProAmatine® is supplied as 2.5-mg, 5-mg and 10-mg tablets for oral administration. The 2.5-
mg tablet is white, round, and biplanar, with a bevelled edge, and is scored on one side with
“RPC” above and “2.5” below the score, and “003” on the other side. The 5-mg tablet is
orange, round, and biplanar, with a bevelled edge, and is scored on one side with “RPC” above
and “5” below the score, and “004” on the other side. The 10-mg is blue, round, and biplanar,
with a bevelled edge, and is scored on one side with “RPC” above and “10” below the score,
and “007” on the other side.
2.5-milligram Tablets: NDC 54092-003-01 Bottle of 100
5.0-milligram Tablets: NDC 54092-004-01 Bottle of 100
10-milligram Tablets:
Store at 25°C (77°F)
Excursions permitted to 15-30˚C (59-86˚F)
[see USP Controlled Room Temperature]
Manufactured for
Shire US Inc., One Riverfront Place, Newport, KY, 41071, USA
by NYCOMED Austria GmbH
2003 Shire US Inc.
Rev. 10/03

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