X-Message-Number: 12310
Date: Mon, 23 Aug 1999 02:30:08 -0700 (PDT)
From: Doug Skrecky <>
Subject: potential use of arginine in freeze-drying

  Mattern M.  Winter G.  Kohnert U.  Lee G.
  Department of Pharmaceutical Technology, Friedrich-Alexander University,
  Erlangen, Germany.
  Formulation of proteins in vacuum-dried
  glasses. II. Process and storage stability in sugar-free amino acid systems.
  Pharmaceutical Development & Technology.  4(2):199-208, 1999 May.
  The purpose of this research was to investigate the freeze- and vacuum-drying
  behavior of L-amino acids of current/potential use as adjuvants for
  formulating proteins. The analytical methods used were
  wide-angle x-ray diffraction, differential scanning calorimetry, and scanning
  electron microscopy. Protein analysis was performed either as an activity
  assay (lactate dehydrogenase [LDH]) or by size-exclusion chromatography
  (granulocyte colony-stimulating factor [rhG-CSF]). After samples were
  freeze-dried, only the four basic amino acids (arginine, lysine, histidine,
  and citrulline) formed amorphous solids, which, however, were partially
  crystalline. The remaining amino acids all formed fully crystalline solids.
  After samples were vacuum-dried, (20 degrees C, 0.1 mbar, 1 ml fill volume in
  2-ml vials) fully crystalline solids were formed by all of the amino acids.
  For arginine, the addition of either HCl, H3PO4, or H2SO4 sufficient to form
  the respective salt produced amorphous solids after vacuum-drying, but they
  had high residual water contents and low glass transition temperatures (Tg).
  Addition of phenylalanine to arginine base inhibited crystallization of the
  latter at low concentrations during vacuum-drying procedure, leading to
  formation of a pure rubbery solid. At higher concentrations the phenylalanine
  crystallized, producing dry products with glass transition temperatures of >
  60 degrees C. The process and storage stability of LDH and rhG-CSF in the
  vacuum-dried phenylalanine/arginine glasses was greatly improved at
  temperatures up to 40 degrees C compared with the unprotected
  proteins. Uptake of moisture during storage was, however, a
  complicating factor, reducing Tg, promoting crystallization, and leading to
  decreased protein stability. The PO4 salt of arginine produced especially
  high glass transition temperatures after it was vacuum-dried. These
  sugar-free amino acid formulations thus are potential
  stabilizes for proteins.

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=12310