Adsorption of salmon calcitonin to PLGA microspheres

S. Calis, L. R. Jeyanthi, T. Tsai, R. C. Mehta, P. P. DeLuca

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

Purpose. The interaction of salmon calcitonin (sCT) and poly (d,l-lactide-co-glycolide) was detected during preparation and evaluation of microspheres. The purpose of this study was to quantitate the extent and nature of the interaction. Methods. Blank microspheres were prepared by an aqueous emulsification solvent extraction technique. Adsorption studies were carried out at six concentrations of sCT and three concentrations of microspheres. Adsorption isotherms were constructed using the Langmuir and Freundlich treatments. Results. Adsorption at 1 mg/ml sCT concentration resulted in almost complete depletion of the peptide from the adsorption medium with the time to reach maximum adsorption decreasing with increasing microsphere concentration. At sCT concentrations below 100 μg/ml, a true equilibrium occurred in 1 hour or less while at higher concentrations (up to 350 μg/ml), a transient equilibrium was reached in 1 to 2 hours, followed by further adsorption of the peptide. The adsorption followed the Langmuir isotherm at concentrations below 200 μg/ml, indicating formation of a monolayer. Multilayer interaction, described by the Freundlich isotherm, occurred at higher concentrations and resulted in complete depletion of sCT from the adsorption medium. The affinity constant during monolayer formation was 0.09 and the plateau surface concentration was 5.1 μg/mg. The multilayer peptide-peptide adsorption showed a lower affinity (0.025) but higher capacity (24 μg/mg) than the monolayer peptide-polymer adsorption. Conclusions. The results show that poly (d,l-lactide-co-glycolide) microspheres have a high adsorption capacity for sCT which must be considered in formulating a controlled delivery product of this peptide.

Original languageEnglish
Pages (from-to)1072-1076
Number of pages5
JournalPharmaceutical Research
Volume12
Issue number7
Publication statusPublished - 1995

Fingerprint

salmon calcitonin
Microspheres
Adsorption
Peptides
Monolayers
Isotherms
Multilayers
polylactic acid-polyglycolic acid copolymer

Keywords

  • Adsorption isotherms
  • Adsorption kinetics
  • Peptide-polymer interaction
  • PLGA
  • Salmon calcitonin

ASJC Scopus subject areas

  • Chemistry(all)
  • Pharmaceutical Science
  • Pharmacology

Cite this

Calis, S., Jeyanthi, L. R., Tsai, T., Mehta, R. C., & DeLuca, P. P. (1995). Adsorption of salmon calcitonin to PLGA microspheres. Pharmaceutical Research, 12(7), 1072-1076.

Adsorption of salmon calcitonin to PLGA microspheres. / Calis, S.; Jeyanthi, L. R.; Tsai, T.; Mehta, R. C.; DeLuca, P. P.

In: Pharmaceutical Research, Vol. 12, No. 7, 1995, p. 1072-1076.

Research output: Contribution to journalArticle

Calis, S, Jeyanthi, LR, Tsai, T, Mehta, RC & DeLuca, PP 1995, 'Adsorption of salmon calcitonin to PLGA microspheres', Pharmaceutical Research, vol. 12, no. 7, pp. 1072-1076.
Calis S, Jeyanthi LR, Tsai T, Mehta RC, DeLuca PP. Adsorption of salmon calcitonin to PLGA microspheres. Pharmaceutical Research. 1995;12(7):1072-1076.
Calis, S. ; Jeyanthi, L. R. ; Tsai, T. ; Mehta, R. C. ; DeLuca, P. P. / Adsorption of salmon calcitonin to PLGA microspheres. In: Pharmaceutical Research. 1995 ; Vol. 12, No. 7. pp. 1072-1076.
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AU - Tsai, T.

AU - Mehta, R. C.

AU - DeLuca, P. P.

PY - 1995

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AB - Purpose. The interaction of salmon calcitonin (sCT) and poly (d,l-lactide-co-glycolide) was detected during preparation and evaluation of microspheres. The purpose of this study was to quantitate the extent and nature of the interaction. Methods. Blank microspheres were prepared by an aqueous emulsification solvent extraction technique. Adsorption studies were carried out at six concentrations of sCT and three concentrations of microspheres. Adsorption isotherms were constructed using the Langmuir and Freundlich treatments. Results. Adsorption at 1 mg/ml sCT concentration resulted in almost complete depletion of the peptide from the adsorption medium with the time to reach maximum adsorption decreasing with increasing microsphere concentration. At sCT concentrations below 100 μg/ml, a true equilibrium occurred in 1 hour or less while at higher concentrations (up to 350 μg/ml), a transient equilibrium was reached in 1 to 2 hours, followed by further adsorption of the peptide. The adsorption followed the Langmuir isotherm at concentrations below 200 μg/ml, indicating formation of a monolayer. Multilayer interaction, described by the Freundlich isotherm, occurred at higher concentrations and resulted in complete depletion of sCT from the adsorption medium. The affinity constant during monolayer formation was 0.09 and the plateau surface concentration was 5.1 μg/mg. The multilayer peptide-peptide adsorption showed a lower affinity (0.025) but higher capacity (24 μg/mg) than the monolayer peptide-polymer adsorption. Conclusions. The results show that poly (d,l-lactide-co-glycolide) microspheres have a high adsorption capacity for sCT which must be considered in formulating a controlled delivery product of this peptide.

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