Role of Nasal Casts for In Vitro Evaluation of Nasal Drug Delivery and Quantitative Evaluation of Various Nasal Casts

Background: Nasal casts may characterize intranasal drug deposition. Methodology: 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. Results: Smallest vertical cross-sectional areas (valve region) for Koken and Optinose right/left: 2.55/2.75 and 1.18/1.18 cm 2 , respectively, versus a ‘normative’ mean (range) of 0.85 cm 2 (0.2–1.6 cm 2 ). Intranasal volumes differed (computed tomography/water fill): Koken, 35.8/38.6 cm 3 and Optinose, 24.1/25.0 cm 3 , versus a ‘normative’ mean (range) of 26.4 cm 3 (20.9–31.1 cm 3 ). Conclusion: Koken cast dimensions are larger than the normal range and the Optinose cast. The validity of casts for regulatory drug deposition studies is suspect.