Dosing and uses of ProAmatine, Orvaten (midodrine)
Adult dosage forms and strengths
tablet
- 2.5mg
- 5mg
- 10mg
Symptomatic Orthostatic Hypotension
2.5-10 mg PO q8hr
Usual dose: 10 mg PO q8hr
Doses greater than 30 mg/day have not been studied; should not exceed 40 mg/day
Stress Incontinence (Off-label)
2.5-5 mg PO q8-12hr
Dosing Modifications
Renal impairment: 2.5 mg PO q8hr; increase as tolerated
Pediatric dosage forms and strengths
Safety & efficacy not established
ProAmatine, Orvaten (midodrine) adverse (side) effects
>10%
Paresthesia (18%)
Piloerection (13%)
Pruritus (13%)
Supine hypertension (7-13%)
Urinary retention or urgency (up to 13%)
1-10%
Chills (5%)
Pain, including abdominal pain (5%)
Rash (2%)
<1%
Anxiety
Canker sore
Confusion
Dizziness
Dry skin
Erythema multiforme
Facial flushing
Flushing
Headache
Hyperesthesia
Insomnia
Intracranial pressure increased
Nausea
Somnolence
Weakness
Xerostomia
Warnings
Black box warnings
May cause marked elevation of supine blood pressure; reserve use for patients whose lives are considerably impaired despite standard clinical care for orthostatic hypotension
Contraindications
Severe organic heart disease, supine HTN, acute renal disease, urinary retention, pheochromocytoma, thyrotoxicosis
Cautions
Concurrent use with digitalis glycosides, beta blockers, or other agents that decrease heart rate
Concomitant use with treatment agents that may cause vasoconstriction
Dm
Hepatic insufficiency
Urinary retention
Vision problems
Take drug no later than 6 pm and 3-4 hr before bed to minimize supine HTn
Pregnancy and lactation
Pregnancy category: C
Lactation: Not known if excreted into breast milk; avoid
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of ProAmatine, Orvaten (midodrine)
Mechanism of action
Alpha-1 selective adrenergic agonist; increases peripheral vascular resistance; arteriolar and venous tone increases and results in a rise in sitting, standing, and supine systolic and diastolic blood pressure in patients with orthostatic hypotension
Absorption
Bioavailability: 93%
Onset: 45-90 min (initial effect); 60 min (max effect)
Duration: 2-3 hr
Peak plasma time: 1-2 hr (desglymidodrine); 30 min (midodrine)
Distribution
Protein bound: MinimaL
Vd: <1.66 L/kg
Metabolism
Extensively undergoes enzymatic hydrolysis in the systemic circulation; prodrug (midodrine) converted to desglymidodrine (active agent)
Metabolites: Desglymidodrine, 15 times as potent as midodrine; primarily responsible for treatment activity (active)
Elimination
Half-life elimination: 3-4 hr (desglymidodrine); 25 min (midodrine)
Dialyzable: HD: Yes
Renal clearance: 385 mL/min
Excretion: Feces (1-2%); urine (80% [desglymidodrine])
