. 2009 Apr 3;26(7):1679–1688. doi: 10.1007/s11095-009-9878-2

Table I.

Observed Degradation Rate Constants K_obs (n = 3) Derived from ln-plots of the Loss of the Main Oxytocin Peak in RP-HPLC from 0.1 mg/ml Oxytocin Formulations Over Time (r² > 0.99) and t_1/2 Calculated as ln2/k_obs

	k_obs at 40°C [day⁻¹]	t_1/2 at 40°C [days]	k_obs at 55°C [day⁻¹]	t_1/2 at 55°C [days]	k_obs at 70°C [day⁻¹]	t_1/2 at 70°C [days]	k_obs at 80°C [day⁻¹]	t_1/2 at 80°C [days]
pH 2.0	0.033	21.0	0.139	5.0	0.637	1.1	1.153	0.6
pH 4.5	0.006^a	115.5^b	0.046	15.1	0.367^b	1.9^b	1.079^a	0.6^a
pH 7.0	0.080	8.7	0.438	1.6	1.606	0.4	3.594^a	0.2^a
pH 9.0	0.096^a	7.2^a	0.479	1.4	2.212^a	0.3^a	5.913	0.1

The relative standard deviation of three independent degradation experiments was below 5% if not marked otherwise in the table

^aRelative standard deviation below 10%

^bRelative standard deviation below 15%