midodrine

[mi´do-drēn″] a vasopressor used as the hydrochloride salt in treatment of hypotension" >orthostatic hypotension; administered orally.

midodrine

(mye-doe-dreen) midodrine,

ProAmatine

(trade name)

Classification

Therapeutic: vasopressors
Pregnancy Category: C

Indications

Symptomatic management of refractory orthostatic hypotension in patients whose livers are impaired.Urinary incontinence.

Action

Activation of alpha-1–adrenergic receptors in arteries and veins.

Therapeutic effects

Increase in vascular tone and BP.

Pharmacokinetics

Absorption: 93% absorbed following oral administration; rapidly converted to desglymidodrine, the active metabolite.Distribution: Desglymidodrine crosses the blood-brain barrier poorly.Metabolism and Excretion: Desglymidodrine is 80% excreted by the kidneys.Half-life: Midodrine—25 min; desglymidodrine—3–4 hr.

Time/action profile (blood levels of active metabolite)

ROUTE	ONSET	PEAK	DURATION
PO	rapid	1–2 hr	2–3 hr

Contraindications/Precautions

Contraindicated in: Urinary retention; Severe organic heart disease; Acute renal disease; Persistent/excessive supine hypertension; Pheochromocytoma; Thyrotoxicosis.Use Cautiously in: History of hypertensionRenal impairment (↓ initial dose); Hepatic impairment; Diabetes mellitus, visual problems, concurrent fludrocortisone (↑ risk of visual disturbances); Obstetric / Pediatric: Pregnancy, lactation or children (safety not established).

Adverse Reactions/Side Effects

Central nervous system

anxiety
confusion
head pressure/fullness
headache
nervousness

Cardiovascular

supine hypertension (most frequent)
bradycardia

Genitourinary

urinary urge/retention/frequency (most frequent)
dysuria (most frequent)

Dermatologic

facial flushing
piloerection (most frequent)
pruritus (most frequent)
rash

Neurologic

paresthesia (most frequent)

Miscellaneous

chills
pain

Interactions

Drug-Drug interaction

↑ risk of bradycardia with digoxin, beta blockers, and antipsychotics.Concurrent use with other alpha-adrenergic agonists including phenylephrine, ephedrine, pseudoephedrine, and dihydroergotamine may result in ↑ pressor effect.Effects may be ↓ by alpha-adrenergic blockers including prazosin, terazosin, and doxazosin.↑ Effects of fludrocortisone (↓ initial dose of fludrocortisone or ↓ salt intake prior to midodrine).

Route/Dosage

Oral (Adults) Orthostatic hypotension—10 mg three times daily; urinary incontinence—2.5–5 mg two to three times daily.

Renal Impairment

Oral (Adults) 2.5 mg three times daily.

Availability (generic available)

Tablets: 2.5 mg, 5 mg, 10 mg

Nursing implications

Nursing assessment

Monitor supine and sitting BP prior to and during therapy.
Assess pattern of urinary output prior to and during treatment for incontinence.
Lab Test Considerations: Monitor renal and hepatic function prior to and periodically during therapy.

Potential Nursing Diagnoses

Decreased cardiac output (Indications)
Risk for injury (Indications)

Implementation

Oral: Administer 3 times daily at 3–4 hr intervals. Do not administer after last meal or within 4 hr of bedtime.

Patient/Family Teaching

Instruct patient to take midodrine as directed. First dose should be taken on or shortly after arising, second dose at midday, and third dose should be taken before evening meal and at least 4 hr before bedtime. Take missed doses as soon as remembered unless almost time for next dose; do not double doses.
Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.

Evaluation/Desired Outcomes

Decrease in signs and symptoms of orthostatic hypotension.
Decrease in the incidence of urinary incontinence.