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MIDODRINE HYDROCHLORIDE

Medical Diagnosis and Drugs, Medications
MIDODRINE HYDROCHLORIDE
(mid'o-dreen)
Orvaten, ProAmatine
Classifications: alpha1 agonist; vasopressor;
Therapeutic: antihypotensive; vasopressor
Prototype: Methoxamine
Pregnancy Category: C

Availability

2.5 mg, 5 mg, 10 mg tablets

Action

Vasopressor and alpha1 agonist. Activates the alpha-adrenergic receptors of the arteries and veins, resulting in increased vascular tone and elevation in blood pressure.

Therapeutic Effect

Affects standing, sitting, and supine systolic and diastolic blood pressures. Indicated by an increase in 1-min standing systolic BP and subjective feelings of clinical improvement.

Uses

Treatment of symptomatic orthostatic hypotension.

Contraindications

Severe organic heart disease; heart failure; acute kidney disease; urinary retention; pheochromocytoma; thyrotoxicosis; MAOI therapy; persistent and excessive supine hypertension; pregnancy (category C).

Cautious Use

Renal impairment, hepatic impairment; history of visual problems; diabetes with hypotension or visual disorders; lactation. Safety and efficacy in children are not established.

Route & Dosage

Orthostatic Hypotension
Adult: PO 10 mg t.i.d. during the daytime hours, dosed not less than 3 h apart with last dose at least 4 h before bedtime (max: 20 mg/dose)

Administration

Oral
  • Do not give at bedtime or before napping (within 4 h of lying supine for any length of time).
  • Give with caution in persons with pretreatment, supine systolic BP ≥170 mm Hg.
  • Store at 15°–30° C (59°–86° F).

Adverse Effects (≥1%)

Body as a Whole: Paresthesia, chills, pain, facial flushing. CNS: Confusion, nervousness, anxiety. CV: Hypertension. GI: Dry mouth. Skin: Pruritus, piloerection, rash. Urogenital: Dysuria, urinary retention, urinary frequency.

Interactions

Drug: may antagonize effects of doxazosin, prazosin, terazosin; may potentiate vasoconstrictive effects of ephedrine, phenylephrine, pseudoephedrine; may cause hypertensive crisis with maois.

Pharmacokinetics

Absorption: Rapidly from GI tract. Peak: Midodrine 0.5 h; desglymidodrine 1–2 h. Metabolism: Rapidly metabolized to desglymidodrine, the active metabolite. Elimination: In urine. Half-Life: Midodrine 25 min, desglymidodrine 3–4 h.

Nursing Implications

Assessment & Drug Effects

  • Lab tests: Evaluate kidney and liver function prior to initiating therapy.
  • Monitor supine and standing BP regularly. Stop drug if supine BP increases excessively; determine acceptable parameters.
  • Monitor carefully effect of the drug in diabetics with orthostatic hypotension and those taking fludrocortisone acetate, which may increase intraocular pressure.

Patient & Family Education

  • Take last daily dose 4 h before bedtime.
  • Report immediately to physician sensations associated with supine hypertension (e.g., pounding in ears, headache, blurred vision, awareness of heart beating).
  • Discontinue drug and report to physician if S&S of bradycardia develop (e.g., dizziness, pulse slowing, fainting).
  • Do not take allergy drugs, cold preparations, or diet pills without consulting physician.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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