Along with fludrocortisone, midodrine is one of the few medications approved for the treatment of orthostatic hypotension. Some of the more common side effects of midodrine include increased blood pressure, headache, dizziness, pounding in the ears, polyuria, anxiety, and scalp pruritus. However, this case, published in the Journal of Pharmacy Practice, describes two rare adverse effects which have only previously been reported in one other human case.
Midodrine, an alpha-1-adrenergic agonist, was almost withdrawn by the FDA in 2010 for a lack of follow-up tests on side effects and clinical benefit. During its trial phase in the 1990s, midodrine did not, in fact, show improvement of orthostatic hypotension symptoms. Even so, the FDA approved the drug in 1996 as it was shown to increase the 1-minute standing blood pressures of patients with orthostatic hypotension.1 Three subsequent clinical trials on the efficacy of midodrine had similar results, but none revealed dysgeusia or dysosmia, the adverse events reported in this case.
The patient at the center of this case study, a 58-year-old male, was hospitalized after experiencing several episodes of vertigo and loss of consciousness. Following his hospitalization he was started on 5mg of midodrine thrice daily by his physician. At a follow-up 2 weeks after treatment began, the patient stated the midodrine was helping his orthostatic hypotension symptoms, though he said he experienced new-onset taste and smell changes described as strong and unbearable.
The patient reported that the taste changes would occur instantly or within 30 minutes after taking a tablet, and that the changes in smell started around an hour after administration. The effects would begin to subside 4 to 5 hours after the dose, by which time he was supposed to take his next dose, thereby causing the symptoms to worsen. The patient’s medication profile included aspirin, acetaminophen, duloxetine, gabapentin, lispro insulin MIX 75/25, loratadine, metformin, omeprazole, oxycodone, topiramate, and ergocalciferol. Some of these have been linked to mild taste disruptions but none have been linked to olfactory perception changes, making the smell disturbances unique.