Pulsatile and sustained peptides release from Zn(II) suspensions.

The dynamics of peptide release from suspensions in the form of solid, sparingly soluble Zn(II)-Peptide complexes in molar ratio 50:1 was observed in vitro conditions. Thyroliberine and dalareline release from suspensions is statistically significant in comparison with gonadrenaline release. Pulsatile character of peptide release in 6 significant peaks of released dalareline, 5--of gonadoreline release and 4--thyroliberine were observed. Thyroliberine was released fastest from the obtained suspensions--63 h +/- 3.1, and dalareline was released slowest--26.5 h +/- 2.3. The release time for gonadoreline from suspensions was 12.0 h +/- 1.0. Molecular weight of the peptide and properties of the Zn(II)-Peptide complexes have major influence upon the character and time of peptide release from suspensions. The greater is the molecular weight and durability of Zn(II)-Peptide complex, the bigger is the number of peaks of the peptide released from suspensions. The release time of the peptides is longer when the molecular weight of the released peptide is bigger.