Study design and treatments
This was a single-centre, prospective, two-sequence, two-period crossover study, in which healthy male subjects were randomised to receive 400 mg zamicastat or placebo.
The study had a double-blind design and was placebo controlled to reduced potential bias. Compared with a parallel-group study, the crossover design reduces the influence of confounding covariates and provides more precise estimates of effects with fewer participants.
The study consisted of a screening evaluation, two treatment periods, and an end-of-study visit. In each treatment period, subjects were administered a 400 mg once-daily oral dose of zamicastat or matching placebo, for 10 days, in fed conditions. The two treatment periods were separated by a washout of at least seven days. Subjects were screened between days -28 to -3 (both inclusive) before the first IMP administration to confirm that they met the eligibility criteria for the study (Figure 1).
On both treatment periods, subjects were admitted to the clinical site two days before (day -2) the first IMP administration. On both treatment periods, the following procedures were completed on the day before (day -1) the first IMP administration: measurement of vital signs (BP, HR, and body temperature); 24-hour urine collection for catecholamines assay; collection of blood for plasma catecholamines concentration, DβH activity determination, and zamicastat and metabolites (BIA 5-453 and BIA 5-961) quantification; and CPT.
On the morning of days 1 to 10, subjects received 400 mg of zamicastat or matching placebo orally, after a moderate breakfast. On days 3, 6, 8, and 10, 24-hour urine was collected for catecholamines assay, and blood samples were collected for DβH activity determination and zamicastat and metabolites quantification. On day 1 and day 10, CPT was performed, and blood was collected for the determination of plasma catecholamines concentration, before and after CPT.
During the treatment days, the following safety assessments were performed: clinical laboratory safety test on day 5 (haematology and biochemistry); ECG on days 1, 3, 5, 7, and 9; and vital signs from day 1 to 10.