Assessing the clinical need for short-term conversion from oral to parenteral angiotensin converting enzyme inhibitor therapy in hypertensive patients: A quinapril to quinaprilat placebo-controlled model

Rationale and study design. This study assesses safety and efficacy when hypertensive patients convert from an oral angiotensin converting enzyme inhibitor, quinapril, to its intravenous counterpart, quinaprilat, and evaluates the need for short-term conversion from oral to parenteral therapy. Blood pressure was measured by clinical measurements using a sphygmomanometer and by 24-h ambulatory blood pressure monitoring. During a placebo-baseline phase, patients' blood pressure had to increase within 3 days in the absence of an angiotensin converting enzyme inhibitor. Responding patients were stabilized on oral quinapril and then randomized to 3 days of double-blind treatment with one 5 ml or 10 ml injection twice daily of quinaprilat or placebo. Results. Overall response to quinaprilat in ambulatory blood pressure monitoring and clinic blood pressure measurements was not statistically or clinically different from the response to oral quinapril therapy during baseline. Withdrawal from quinapril resulted in clinically significant increases in all blood pressure measurements compared with baseline therapy; the differences between placebo and quinaprilat therapy were statistically and clinically significant. Two patients treated with quinaprilat withdrew due to hypotension; one patient required a dosage reduction. Parenteral quinaprilat safely maintained blood pressure control whereas placebo control did not during the 72-h interruption of quinapril.