Purpose: A case of mild symptomatic hypotension after treatment with menaquinone (vitamin K(2)) is reported.
Summary: A 62-year-old white man with a medical history of hyperlipidemia, coronary artery disease, and benign prostatic hyperplasia was started on a regimen of menaquinone 100 μg daily as a supplement to his medications for coronary artery disease. Approximately two hours after taking the first dose of menaquinone, the patient experienced sudden weakness and dizziness. At that time, his blood pressure was 110/55 mm Hg. On day 2 of treatment, his blood pressure was 105/50 mm Hg two hours after taking menaquinone; however the patient was asymptomatic. On day 3, the patient's blood pressure was 100/50 mm Hg two hours after menaquinone ingestion, with symptoms of generalized weakness and dizziness, at which point menaquinone was discontinued. All of the patient's heart rate measurements were within normal limits during this time. The day after discontinuing menaquinone, the patient's blood pressure was 115/65 mm Hg, after which his readings were within normal limits on subsequent days. After a 10-day menaquinone-free period, the patient was rechallenged. On rechallenge day 1, the patient's blood pressure was 115/60 mm Hg two hours after menaquinone ingestion; on rechallenge day 2, his blood pressure was 100/55 mm Hg. The patient was asymptomatic on both days of the rechallenge. The Naranjo et al. adverse drug reaction probability scale score was 7, indicating a probable adverse reaction to menaquinone. The drug interaction probability scale score for this case was 6, indicating that a drug interaction was probable.
Conclusion: A 62-year-old white man developed mild symptomatic hypotension while receiving menaquinone therapy.