From the Guidelines
Midodrine is not typically associated with tachycardia, but rather reflex bradycardia, due to its alpha-1 adrenergic agonist properties, as noted in the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1. When midodrine increases blood pressure by causing peripheral vasoconstriction, the body's baroreceptors detect this elevation and trigger a compensatory slowing of heart rate. If a patient on midodrine experiences tachycardia, this is likely not a direct effect of the medication and warrants further investigation for other causes, such as:
- Anxiety
- Dehydration
- Hyperthyroidism
- Anemia
- Other medications The most recent and highest quality study, the 2017 ACC/AHA/HRS guideline, recommends midodrine as a reasonable treatment option for patients with recurrent vasovagal syncope (VVS) with no history of hypertension, heart failure, or urinary retention 1. Midodrine is typically prescribed at 2.5-10 mg three times daily, with the last dose taken at least 4 hours before bedtime to avoid supine hypertension, as noted in the study published in Diabetes/Metabolism Research and Reviews in 2011 2. Patients should monitor their blood pressure and heart rate regularly while taking midodrine, especially when starting therapy or changing doses. It is essential to investigate other potential causes of tachycardia and adjust the midodrine dosage or evaluate for drug interactions as needed, to prioritize the patient's morbidity, mortality, and quality of life outcomes.
From the Research
Midodrine and Tachycardia
- Midodrine is a peripheral alpha-adrenergic agonist used to treat orthostatic hypotension and secondary hypotensive disorders 3, 4.
- The drug increases standing blood pressure and improves symptoms of orthostatism without associated cardiac stimulation 3.
- Midodrine is well-tolerated, with common adverse events including piloerection, pruritus, paraesthesias, urinary retention, and chills 4.
- There is no direct evidence in the provided studies that midodrine causes tachycardia, but it can cause cardiovascular complaints, which are generally mild and can be controlled by reducing the dosage of midodrine 3.
Orthostatic Hypotension Treatment
- Midodrine is an effective therapeutic option for the management of various forms of orthostatic hypotension 4, 5.
- Pyridostigmine can also improve standing blood pressure in patients with orthostatic hypotension without worsening supine hypertension 6, 5.
- The combination of midodrine and pyridostigmine can be effective in treating orthostatic hypotension, with midodrine being better at improving OH-related symptoms 5.
- Other treatment options for primary orthostatic hypotension include droxidopa, fludrocortisone, atomoxetine, and sympathomimetic agents, with midodrine and droxidopa having the most evidence for increasing blood pressure and alleviating symptoms 7.