In vitro studies show that clevidipine butyrate and its metabolite at the concentrations achieved in clinical practice will not inhibit or induce any CYP enzyme.

In a clinical study with radiolabeled clevidipine butyrate, 83% of the drug was excreted in urine and feces. The major fraction, 63-74% is excreted in the urine, 7-22% in the feces. More than 90% of the recovered radioactivity is excreted within the first 72 hours of collection.

Clevidipine butyrate displayed positive genotoxic potential in vitro in the Ames test, mouse lymphoma thymidine kinase locus assay, and chromosomal aberration assay but not in vivo in the mouse micronucleus test. Formaldehyde, a metabolite of clevidipine butyrate, a known genotoxicant in vitro and a probable human carcinogen, appears to be at least partially responsible for the positive in vitro results. Long-term studies for eva luation of carcinogenic potential have not been performed with clevidipine butyrate due to the intended short-term duration of human use. There were no adverse effects on fertility or mating behavior of male rats at clevidipine butyrate doses of up to 55 mg/kg/day, approximately equivalent to the maximum recommended human dose (MRHD) of 504 mg/day (21 mg/hour x 24 hours) on a body surface area basis. Female rats demonstrated pseudopregnancy and changes in estrus cycle at doses as low as 13 mg/kg/day (about 1/4 the MRHD); however, doses of up to 55 mg/kg/day did not affect mating performance or fertility.

When pregnant rats were dosed with clevidipine butyrate during late gestation and lactation, there were dose-related increases in mortality, length of gestation and prolonged parturition at dose levels as low as 13 mg/kg/day (about 1/4 the maximum recommended human dose of 504 mg/day (21 mg/hour x 24 hours) on a body surface area basis). When offspring of these dams were mated, they had a conception rate lower than that of controls. Clevidipine butyrate crosses the placental membrane in this species and doses of 35 or more mg/kg/day (about 0.7 times the MRHD) administered during organogenesis adversely affected fetal survival. Fetal survival was also adversely affected when pregnant rabbits were treated during organogenesis with 55 mg/kg/day (about twice the MRHD on a body surface area basis).

Cleviprex was eva luated in two double-blind, randomized, parallel, placebo-controlled, multicenter trials of cardiac surgery patients—pre-operative use in ESCAPE-1 (n=105) and post-operative use in ESCAPE-2 (n=110). Patients were undergoing coronary artery bypass grafting, with or without valve replacement. Inclusion in ESCAPE-1 required a systolic pressure ≥160 mmHg. In ESCAPE-2, the entry criterion was systolic pressure of ≥140 mmHg within 4 hours of the completed surgery. The mean baseline blood pressure was 178/77 mmHg in ESCAPE -1 and 150/71 mmHg in ESCAPE 2. The population of both studies included 27% females and 47% patients older than age 65.

Cleviprex was infused in ESCAPE-1 preoperatively for 30 minutes, until treatment failure, or until induction of anesthesia, whichever came first. Cleviprex was infused in ESCAPE-2 postoperatively for a minimum of 30 minutes unless alternative therapy was required. The maximum infusion time allowed in the ESCAPE studies was 60 minutes.

In both studies infusion of Cleviprex was started at a dose of 1- 2 mg/hour and was titrated upwards, as tolerated, in doubling increments every 90 seconds up to