Figure 16.

Two 24-hour ambulatory blood pressure monitoring records (based on individual readings), starting at 10 a.m., of a 63-year old woman taking Verapamil hydrochloride for migraine. Both the records show normal blood pressure during the waking hours. (a) Shows that when she was taking Verapamil at bedtime, during sleep there was a marked degree of nocturnal arterial hypotension (blood pressure falling as low as 80/30 mm Hg). (b) Shows markedly less nocturnal hypotension on stopping the bedtime dose of Verapamil (lowest blood pressure 110/50 mm Hg)