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-(β-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:Soluble

                   Methanol: Sparingly soluble

pKa: 7.8 (0.3% aqueous solution) pH: 3.5 to 5.5 (5% aqueous solution)

Melting Range: 200 to 203°C

Last updated on RxList: 5/6/2008

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.

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.

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: NDC 54092-007-01 Bottle of 100

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. Rev. 10/03. FDA revision date: 7/22/2004

Last updated on RxList: 5/6/2008

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

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.

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.

Last updated on RxList: 5/6/2008

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® .

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.

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/m²basis, 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.

Last updated on RxList: 5/6/2008

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 induced emesis and administration of alpha-sympatholytic drugs (e.g., phentolamine).

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.

Last updated on RxList: 5/6/2008

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.

Last updated on RxList: 5/6/2008

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.

Last updated on RxList: 5/6/2008

IMPORTANT NOTE: This is a summary and does not contain all possible information about this product. For complete information about this product or your specific health needs, ask your health care professional. Always seek the advice of your health care professional if you have any questions about this product or your medical condition. This information is not intended as individual medical advice and does not substitute for the knowledge and judgment of your health care professional. This information does not contain any assurances that this product is safe, effective, or appropriate for you.

MIDODRINE - ORAL

(MY-doh-dreen)

COMMON BRAND NAME(S): ProAmatine

WARNING: Midodrine should only be used in carefully selected patients. When you are lying on your back, this medication causes a significant increase in blood pressure. Your blood pressure will be monitored carefully during treatment.

USES: This medication is used for certain patients who have symptoms of low blood pressure when standing. This condition is also known as orthostatic hypotension. Midodrine is used in people whose daily activities are severely affected by this condition, even after other treatments are used (e.g., support stockings). It is known as a sympathomimetic (alpha receptor agonist) that acts on the blood vessels to raise blood pressure.

HOW TO USE: Take this medication by mouth with or without food, usually 3 times daily with at least 4 hours between doses or as directed by your doctor. Follow all your doctor's instructions carefully. This drug is taken during daytime hours, when people stand most often. This medicine should not be taken after the evening meal or less than 4 hours before bedtime. Taking your dose is not recommended if you plan to lie down for a long time afterward (e.g., taking a nap).

Dosage is based on your medical condition and response to treatment. Usually, your doctor will start you at a low dose and gradually increase your dose in order to reduce side effects. Do not increase your dose or take it more frequently than prescribed.

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same times each day.

Tell your doctor if your condition persists or worsens. This drug should be continued only in those people whose symptoms improve during treatment.

SIDE EFFECTS: Skin tingling, chills, "goose bumps," stomach pain, or urinary problems (strong/frequent urge to urinate, frequent urination, trouble urinating) may occur. Less common side effects include dry mouth, dizziness, drowsiness, trouble sleeping, or leg cramps. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

This medication can cause your blood pressure to increase, especially when you are lying down (supine hypertension). Stop taking midodrine and contact your doctor immediately if you experience the following signs of supine hypertension: pounding heartbeat, pounding in the ears, headache, blurred vision.

Tell your doctor immediately if any of these unlikely but serious side effects occur: slow heartbeat, unusual feeling in the chest, fainting, pressure/fullness in the head, confusion, anxiety, weakness, vision problems.

A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching, swelling, severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

Contact your doctor for medical advice about side effects. The following numbers do not provide medical advice, but in the US you may report side effects to the Food and Drug Administration (FDA) at 1-800-FDA-1088. In Canada, you may call Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking midodrine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: high blood pressure, pheochromocytoma, thyroid disease (severe hyperthyroidism), severe difficulty urinating (urinary retention).

Before using this drug, tell your doctor your entire medical history, including: heart disease, liver disease, kidney disease, diabetes.

Get up slowly to reduce dizziness when rising from a sitting or lying position. Also, limit your intake of alcoholic beverages, which will worsen this effect.

This drug may rarely make you dizzy or drowsy or cause blurred vision. Use caution while driving, using machinery, or doing any activity that requires alertness or clear vision.

Before having surgery, tell your doctor or dentist that you are taking this medication.

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

It is not known whether this drug passes into breast milk. Because this medication could have undesirable effects on a nursing infant, breast-feeding while using this drug is not recommended. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: Your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor or pharmacist first.

Avoid taking MAO inhibitors (e.g., furazolidone, isocarboxazid, linezolid, moclobemide, phenelzine, procarbazine, rasagiline, selegiline, tranylcypromine) within 2 weeks before or after treatment with this medication. In some cases, a serious (possibly fatal) drug interaction may occur.

Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: adrenaline-like drugs (e.g., ephedrine, phenylephrine, pseudoephedrine), alpha blockers (e.g., doxazosin, prazosin, terazosin), beta-blockers (e.g., atenolol, metoprolol), digoxin, ergot alkaloids (e.g., dihydroergotamine, ergotamine), drugs to control high blood pressure, psychiatric medications (especially certain antidepressants and antipsychotic drugs).

If you are also taking fludrocortisone for low blood pressure when standing, be sure to regularly monitor your blood pressure, especially when you are lying down. You will be at a greater risk for developing supine hypertension while using these 2 drugs together. (See also Side Effects section.)

Check the labels on all your medicines (e.g., cough-and-cold products, diet aids) because they may contain ingredients that could increase your blood pressure. Ask your pharmacist about using those products safely.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.

OVERDOSE: If overdose is suspected, contact your local poison control center or emergency room immediately. US residents can call the US National Poison Hotline at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include "goose bumps," difficulty urinating, feeling cold.

NOTES: Do not share this medication with others.

Blood pressure checks (lying, sitting, and standing) should be routinely taken. Share the results with your doctor. (See also Side Effects section.)

You may lessen high blood pressure while lying down by sleeping with the head of the bed lifted up.

Laboratory and/or medical tests (e.g., kidney function, liver function) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.

MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

STORAGE: Store at room temperature at 77 degrees F (25 degrees C) away from light and moisture. Brief storage between 59 and 86 degrees F (15 and 30 degrees C) is permitted. Do not store in the bathroom. Keep all medicines away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.

Information last revised July 2008 Copyright(c) 2008 First DataBank, Inc.