Abstract:
Salmon calcitonin (CT) is a peptide used in the treatment of osteoporosis and other bone-related disorders. It is currently available in Thailand as an injection and a nasal spray solution, both of which are imported resulting in a high cost of medication and limited usage. The main objective of this study was to develop salmon CT nasal spray preparations that could provide acceptable stability and bioavailability at a more economical cost. Two strengths (100 and 200 IU per actuation) of salmon CT nasal sprays were prepared (two batches each). The formulation was an isotonic solution of synthetic salmon CT with appropriate preservative, buffer and tonicity adjuster. A special spray pump was used that could provide an accurate and reproducible spray volume of 0.09 ml per actuation. The stability studies consisted of real-time testing at 4 ℃ (recommended storage condition) for 12 months and at 30 ℃ (accelerated condition) for 4 months. Samples were taken periodically to determine for salmon CT content as well as its degradation product (calcitonin C) and related peptide (N-acetyl-cys1-calcitonin) by HPLC. The percent labeled amount of all four batches was within 90.0 - 115.0 % ranges. The prepared nasal sprays also complied with the tests for calcitonin C and related peptide as well as the clarity, pH, osmolarity, uniformity of mass and sterility tests under both storage conditions. The reproducibility of the pump spray performance was also confirmed based on the results from the leak test, droplet size distribution and spray pattern evaluation. The in vivo bioavailability of the test product (200 IU strength) relative to the innovator product was further evaluated in 12 healthy male volunteers. Each subject received a total single dose of 400 IU salmon CT in a two-way crossover study. The plasma concentrations of salmon CT were determined by radioimmunoassay. There were no statistically significant differences in the corresponding pharmacokinetic parameters (AUC and C[subscript max]) between the two products (p > 05, ANOVA). The 90% confidence intervals for the ratio of the two parameters (test to innovator) based on the log-transformed data were within the 80.0 -125.0% bioequivalence range. Thus, it can be concluded that the prepared salmon CT nasal spray solutions were both pharmaceutically equivalent and bioequivalent to the innovator product.