LISBON — Intravenous diazoxide was as safe and effective as intravenous hydralazine for treating hypertensive crisis during pregnancy in a study with 124 patients.
Diazoxide has the advantage of working very quickly, and it may be a good option for physicians who are uncomfortable with hydralazine, Dr. Annemarie Hennessy said at the 15th World Congress of the International Society for the Study of Hypertension in Medicine. Intravenous β-blockers, another option for physicians in the United States, are not approved for use in Australia.
Women with severe hypertension at Royal Prince Alfred Hospital in Sydney were randomized so that 63 were assigned to treatment with diazoxide and 61 were scheduled to receive hydralazine. Treatment was actually administered to 59 women in the diazoxide group and 51 women in the hydralazine group, said Dr. Hennessy, a nephrologist at the University of Sydney and managing director of the preeclampsia research laboratory at the hospital.
The dosage used for diazoxide was a 15-mg bolus administered every 3 minutes to a maximum of 300 mg. In the hydralazine group, patients received 5 mg every 20 minutes to a maximum of 15 mg. The study's primary end point was need for cesarean section because of fetal deterioration as determined by cardiotocography.
The cesarean section rate was 70% in the hydralazine group and 76% in the diazoxide group, not a statistically significant difference.
The average time to reach target blood pressure was 34 minutes in the hydralazine group and 19 minutes in the diazoxide group, a statistically significant difference that is probably not very significant clinically, Dr. Hennessy said.
Episodes of persistent, severe hypertension occurred in 38% of women receving hydralazine and 16% of those receiving diazoxide, a statistically significant difference. There was one episode of severe hypotension in the hydralazine group and none in the diazoxide group. The incidence of other adverse events was 11% in both groups.
Dr. Hennessy attributed the absence of diazoxide-related hypotensive episodes in this study to the use of 15-mg boluses, which produced a controlled reduction in blood pressure.