Prolonged Hypotension Induced by Ingesting a Topical Minoxidil Solution: Analysis of Minoxidil and Its Metabolites

In 2016, a 47-year-old man suffered prolonged hypotension after ingesting 60 mL of a topical minoxidil solution, equivalent to 3,000 mg of minoxidil. His serum concentration of minoxidil sharply decreased from 4,994 ng/mL to 33.9 ng/mL within 12 hours, yet he still required vasopressor support for four days. Urine analysis 16 hours after ingestion revealed higher levels of minoxidil-O-glucuronide (1,953 ng/mL) than unchanged minoxidil (360.4 ng/mL) or minoxidil-N-O-sulfate (104.5 ng/mL). The case demonstrated that ingestion of large amounts of topical minoxidil can lead to severe and lasting cardiovascular effects, and monitoring minoxidil-O-glucuronide in urine is an effective method for diagnosing minoxidil poisoning.