Drug Guide
Midodrine Hydrochloride
Classification
Therapeutic: Vasopressor/Antihypotensive agent
Pharmacological: Alpha-1 adrenergic agonist
FDA Approved Indications
- Orthostatic hypotension
Mechanism of Action
Midodrine is a prodrug that is converted into desglymidodrine, an active metabolite that selectively activates alpha-1 adrenergic receptors on blood vessels, leading to vasoconstriction and an increase in blood pressure.
Dosage and Administration
Adult: Initial dose: 2.5 mg orally three times daily, administered during daytime hours. Dose may be titrated up to 10 mg three times daily based on response and tolerability.
Pediatric: Not approved for pediatric use; safety and efficacy have not been established.
Geriatric: No specific dosage adjustment required, but careful monitoring is recommended due to increased risk of adverse effects.
Renal Impairment: Use with caution; dose adjustments may be necessary depending on severity.
Hepatic Impairment: No specific adjustments recommended, but caution advised.
Pharmacokinetics
Absorption: Rapidly absorbed from the gastrointestinal tract.
Distribution: Widely distributed; crosses the blood-brain barrier.
Metabolism: Metabolized mainly in the liver to desglymidodrine.
Excretion: Excreted primarily via the kidneys.
Half Life: Approximately 3-4 hours.
Contraindications
- Increased risk of supine hypertension
- Acute renal failure
Precautions
- Monitor blood pressure regularly, especially in the supine and upright positions.
- Use with caution in patients with cardiac disease or urinary retention.
- Avoid use before bedtime to prevent supine hypertension.
Adverse Reactions - Common
- Piloerection (Common)
- Itching or tingling sensation in the scalp or face (Common)
- Supine hypertension (Common)
Adverse Reactions - Serious
- Hypertension (severe or persistent) (Less common)
- Painless ischemic complications (Rare)
- Urinary retention (Rare)
- Severe hypertension leading to cerebrovascular events (Rare)
Drug-Drug Interactions
- Other agents that increase blood pressure or vasoconstrictors
- Certain antidepressants
Drug-Food Interactions
- No significant food interactions reported
Drug-Herb Interactions
- Limited data; exercise caution with herbal sympathomimetics
Nursing Implications
Assessment: Monitor blood pressure regularly, with particular attention to supine and standing readings.
Diagnoses:
- Risk for hypertension
- Risk for falls due to hypotension or hypertension.
Implementation: Administer doses with meals or at least 4 hours before bedtime. Educate patients on monitoring blood pressure and recognizing symptoms of hypertension.
Evaluation: Assess effectiveness by improvements in orthostatic symptoms and maintaining blood pressure within target range.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Do not stop suddenly; dose tapering may be necessary.
- Monitor blood pressure regularly and report significant increases or symptoms of hypertension.
- Rise slowly from sitting or lying position to prevent dizziness.
Special Considerations
Black Box Warnings:
- Use with caution due to risk of supine hypertension; avoid administration near bedtime.
- Potential for ischemic events with excessive vasoconstriction.
Genetic Factors: N/A
Lab Test Interference: No known interference.
Overdose Management
Signs/Symptoms: Severe hypertension, headache, dizziness, flushing, piloerection, restlessness.
Treatment: Discontinue medication, maintain airway, monitor cardiovascular status, and treat hypertension with appropriate antihypertensive agents if necessary.
Storage and Handling
Storage: Store at room temperature, away from light and moisture.
Stability: Stable for at least 24 months when properly stored.