What are the contraindications for midodrine?

Midodrine Contraindications

Midodrine is contraindicated in patients with severe organic heart disease, acute renal disease, urinary retention, pheochromocytoma, thyrotoxicosis, and persistent/excessive supine hypertension. 1

Absolute Contraindications

• Severe organic heart disease - Midodrine can increase peripheral vascular resistance which may worsen cardiac function in patients with severe heart disease
• Acute renal disease - May worsen renal function through vasoconstriction
• Urinary retention - Midodrine can exacerbate urinary retention through increased sphincter tone 2
• Pheochromocytoma - Can precipitate hypertensive crisis in patients with catecholamine-secreting tumors
• Thyrotoxicosis - May worsen cardiovascular symptoms
• Persistent and excessive supine hypertension - Midodrine can significantly worsen supine hypertension 1

Relative Contraindications/Use with Caution

Cardiovascular Conditions

• Congestive heart failure (CHF) - Midodrine should be used cautiously in patients with CHF due to potential worsening of cardiac function 3
• Patients using negative chronotropic agents - Use with caution in patients taking:
  • Beta-blockers
  • Digoxin
  • Non-dihydropyridine calcium channel blockers 3

Medication Interactions

• Other α-adrenergic agents - Concomitant use with ephedrine, pseudoephedrine, and phenylpropanolamine should be avoided as this may aggravate supine hypertension 3
• α-adrenergic blockers - Midodrine can antagonize the actions of α-blockers (terazosin, prazosin, doxazosin) 3

Special Populations

• Dialysis patients - While midodrine is used for intradialytic hypotension, it is effectively cleared by hemodialysis with a reduced half-life of 1.4 hours 3
• Spinal cord injury patients - May silently lead to progressive urinary retention in patients who void spontaneously 2

Monitoring Requirements

When prescribing midodrine, patients should be monitored for:

1. Supine hypertension - Occurs in up to 10% of patients on long-term therapy, requiring cessation of treatment 3, 4
2. Bradycardia - Due to reflex parasympathetic stimulation 3
3. Urinary retention - Particularly in patients with pre-existing prostatic hypertrophy or bladder outflow obstruction 2

Risk Mitigation Strategies

• Schedule the final daily dose at least 4 hours before bedtime to reduce the risk of supine hypertension 4
• Start with lower doses (2.5mg) and titrate based on symptoms and blood pressure response 5
• For dialysis patients, administer 30 minutes before dialysis sessions to improve intradialytic blood pressure 3
• Consider alternative treatments for orthostatic hypotension in patients with contraindications, such as fludrocortisone or non-pharmacological measures 3

Proper patient selection and careful monitoring can help maximize the benefits of midodrine while minimizing potential adverse effects in the management of orthostatic hypotension.