Formulation for a novel inhaled peptide therapeutic for idiopathic pulmonary fibrosis

Abstract

A caveolin-1 scaffolding domain, CSP7, is a newly developed peptide for the treatment of idiopathic pulmonary fibrosis. To develop a CSP7 formulation for further use we have obtained, characterized and compared a number of lyophilized formulations of CSP7 trifluoroacetate with DPBS and in combination with excipients (mannitol and lactose at molar ratios 1:5, 70 and 140). CSP7 trifluoroacetate was stable (>95%) in solution at 5 and 25°C for up to 48 hours and tolerated at least 5 freeze/thaw cycles. Lyophilized cakes of CSP7 trifluoroacetate with excipients were stable (>96%) for up to 4 weeks at room temperature (RT), and retained more than 98% of the CSP7 trifluoroacetate in the solution at 8 hours after reconstitution at RT. The lyophilized CSP7 formulations were stable for up to 10 months at 5°C protected from moisture. Exposure of the lyophilized cakes of CSP7 to 75% relative humidity (RH) resulted in an increase in the absorbed moisture, promoted crystallization of the excipients and induced reversible formation of CSP7 aggregates. Increased molar ratio of mannitol slightly affected formation of the aggregates. In contrast, lactose significantly decreased (up to 20-times) aggregate formation with apparent saturation at the molar ratio of 1:70. The possible mechanisms of stabilization of CSP7 trifluoroacetate in solid state by lactose include physical state of the bulking agent and the interactions between lactose and CSP7 trifluoroacetate (e.g., formation of a Schiff base with the N-terminal amino group of CSP7). Finally, CSP7 trifluoroacetate exhibited excellent stability during nebulization of formulations containing mannitol or lactose.

Formulation Composition and Process Affect Counterion for CSP7 Peptide

“…Various counterions also affect the stability of CSP7 in solution. Hengsawas et al previously reported that CSP7 TFA was stable after 24 h of shaking on an orbital shaker at 5 °C and 25 °C [22]. However, we found that CSP7 acetate was also physically unstable after 6 h of shaking on an orbital shaker at 5 °C and 25 °C.…”

“…The effect of various counterions on the stability of CSP7 was also compared with the results from the previous study. Hengsawas et al reported that Formulation 5 was chemically and physically stable after one month of storage at 25 °C and 60% RH [22]. We found that lyophilization did not affect the presence of TFA counterions.…”

“…Samples were lyophilized using VirTis BenchTop lyophilizer (SP Scientific, Gardiner, NY, USA). The lyophilization cycle is shown in Table 2 [22]. The lyophilized chamber was filled with nitrogen gas after the secondary drying step.…”

“…TFA binds specifically to basic positively charged amino acid side chains and the free N-terminal amino group, forming TFA salt [21]. Recently, CSP7 as a trifluoroacetate (TFA) salt was developed as a lyophilized powder [22]. The lyophilized CSP7 TFA formulated with mannitol and DPBS was physically and chemically stable after storage at 25 °C for up to one month and at 5 °C for up to 10 months [22].…”

“…Recently, CSP7 as a trifluoroacetate (TFA) salt was developed as a lyophilized powder [22]. The lyophilized CSP7 TFA formulated with mannitol and DPBS was physically and chemically stable after storage at 25 °C for up to one month and at 5 °C for up to 10 months [22]. CSP7 TFA remained stable after reconstitution and nebulization via the Aeroneb Pro ® vibrating mesh nebulizer [22].…”