Cadralazine for the treatment of preeclampsia. An open, noncomparative, dose-finding pilot study.

The antihypertensive effect, tolerability, and influence on placental and fetal circulation of cadralazine, a 6-substituted derivative of 3-hydrazinopyridoxine structurally related to hydralazine, was assessed in 46 preeclamptic patients in the third trimester of pregnancy and with diastolic blood pressure of 100-120 mm Hg after 24 hours of bed rest. Patients who fulfilled the inclusion criteria at the initial report (24-48-hour run-in period after hospitalization) entered the titration period. During titration, cadralazine was administered at an initial dose of 5 mg once a day; if after 3 days diastolic blood pressure was still above 90 mm Hg, 5 mg more was added for another 3 days, and so forth, until the maximum dose (20 mg once a day) was reached. Patients who did not lower diastolic blood pressure below 90 mm Hg were considered nonresponders; those who achieved the desired diastolic level (responders) entered the maintenance period, which lasted until delivery. Eight patients delivered during the titration period (premature discontinuation group). A significant decrease in systolic and diastolic blood pressures was observed between the initial report and the titration period. During titration, there were 27 responders (71%) and 11 nonresponders. One of the responders was lost to follow-up. Cadralazine proved to be effective in lowering blood pressure levels; in the group of responders, a mean diastolic reduction of 20% was observed. This significant decrease was not affected by the diastolic blood pressure increase observed at the end of gestation. No adverse effects from the drug were observed on fetal development or immediate postnatal adaptation to stress during labor, and only mild maternal side effects were detected (headache).