Peptide Storage

Storage

The following paragraph comes from a study that sent the peptide home with study participants for self-administration.

Vials were stored frozen until dispensed to the subjects, then kept at 4 C for 10 days at home. High performance liquid chromatographic analysis showed that the peptide was stable at 4 C for at least 2 weeks.

The following seems to indicate that GHRP-6 which is a simple peptide chain unlike IGF-1 which is more complex, is relatively resistant to degradation under the right circumstances at room temperature for almost five years.

The influence of the various buffer species (acetate, citrate, phosphate and borate) was shown to be different and the maximum stability of GHRP-6 was revealed to be in acetate buffer of pH 5.5-6.0. Degradation of GHRP-6 was greater in citrate-containing buffers than in acetate-containing ones. Furthermore, in the citrate-containing buffers, the higher buffer concentration caused greater degradation than the lower ones, but the concentration effect was negligible in acetate-containing buffers. Aqueous solution of GHRP-6 buffered with acetate (0.01 M, pH 5.5) showed a predicted t90% of 4.73 years at 20°C. – Degradation kinetics of growth hormone-releasing hexapeptide (GHRP-6) in aqueous solution, In Sik Ha… International Journal of Pharmaceutics Volume 144, Issue 1, 22 November 1996, Pages 91-97

5.5.4 Storage in solid state

Lyophilized powders can be quite stable as long as they are not reconstituted.
For example, Activase® lyophilized powder shows no significant loss of
bioactivity after storage for more than 4 years at controlled room temperature.

Degradation in the solid state often takes place by aggregation. The
stability of a protein in the solid state is dependent on the moisture content
of the solid, temperature, and composition of the formulation….

These degradation factors become more important the longer the chain of amino acids becomes & with the inclusion of amino acids sensitive to degradation.

Storage of unreconstituted peptides in frozen form (devoid of moisture) is always far more preferable for long-term storage then reconstituted peptides.

GHRP-6 is a simple chain with no extra-sensitive amino acids. But Growth Hormone Releasing Hormone (GHRH) is more sensitive because it is a longer chain composed of some sensitive amino acids. The added bioconjugation complex of CJC-1295 appears to be stable and shouldn’t effect degradation/life of the peptide it is attached to…GHRH.

To answer stability questions the best way is to find studies that specifically examine the stability of the peptide you are interested in.

We have already looked to a very comprehensive study of GHRP-6 now lets look at a stability study for a slightly modified GHRH (and by undeclared assumption CJC-1295).

Investigation of the chemical stability of a new growth hormone-releasing hormone (GHRH) analogue by HPLC, M Idei, I Mezo, EZ Szabo, and G Keri, Biomed Chromatogr, March 1, 1996; 10(2): 89-91

The stability of a new active growth hormone-releasing hormone analogue (D-Ala2,Nle27,(gamma-amino-butyric acid)30-GHRH(1-30)-NH2) was investigated during storage at different temperatures in aqueous solution. Samples stored for various periods of time were analysed by HPLC.

It is concluded that in aqueous solution D-Ala2, Nle27,(gamma-amino-butyric acid)30-growth hormone-releasing hormone (1-30)-NH2 is stable: at least for 36 days at 4 degrees C; for 28 days at 25 degrees C; and for 10 days at 37 degrees C.

Leave a Reply