A pharmacokinetic study of radiprodil oral suspension in healthy adults comparing conventional venous blood sampling with two microsampling techniques

In this phase I, single‐center, open‐label study of ten heathy adults (18‐45 years; NCT02647697), the PK, safety, and tolerability profile of radiprodil oral suspension in healthy adults were assessed, as well as two PK microsampling techniques. All participants received a single 30 mg radiprodil dose (12 mL oral suspension). Blood was collected at various time points using conventional venous sampling (intravenous catheter or venepuncture), and Mitra™ and Aqua‐Cap™ Drummond microsampling (finger‐prick and blood taken from venous blood sample tubes). Geometric mean radiprodil plasma concentrations from conventional venous samples were above the lower limit of quantification up to 48 hours after administration of a single oral dose of radiprodil. Geometric mean AUC (inf) and C (max) were 2042 h ng mL (−1) and 89.4 ng mL (−1), respectively. Geometric mean t (½) was 15.8 hour; median t (max) was 4 hour (range: 3‐6 hour). Radiprodil exposure variables for Aqua‐Cap™ Drummond sampling were similar to the conventional venous‐derived data. Conversely, radiprodil exposure variables were lower with Mitra™ sampling compared with conventional venous sampling. The geometric mean ratio (90% confidence interval) for C (max) of conventional venous versus Mitra™ and Aqua‐Cap™ Drummond sampling (finger‐prick blood) was 0.89 (0.85, 0.94) and 1.03 (0.97,1.08), respectively, and therefore within the conventional bioequivalence range (0.80‐1.25). Radiprodil oral suspension had an acceptable safety, tolerability, and palatability profile. The PK profile of radiprodil oral suspension was established in healthy adults, and was comparable when analyzed using conventional versus microsampling techniques. These results will support future radiprodil paediatric studies.