Role of nasal casts for in vitro evaluation of nasal drug delivery and quantitative evaluation of various nasal casts

Nasal casts may characterize intranasal drug deposition. The Koken cast, described as 'anatomically correct', and the Optinose cast, derived from MRI of a healthy male during velum closure, were dimensionally compared and assessed for deposition assessment suitability. Smallest vertical cross-sectional areas (valve region) for Koken and Optinose right/left: 2.55/2.75 and 1.18/1.18 cm , respectively, versus a 'normative' mean (range) of 0.85 cm (0.2-1.6 cm ). Intranasal volumes differed (computed tomography/water fill): Koken, 35.8/38.6 cm and Optinose, 24.1/25.0 cm , versus a 'normative' mean (range) of 26.4 cm (20.9-31.1 cm ). Koken cast dimensions are larger than the normal range and the Optinose cast. The validity of casts for regulatory drug deposition studies is suspect.