α-Chymotrypsin-catalyzed degradation of desmopressin (dDAVP): influence of pH, concentration and various cyclodextrins

• Published in: International journal of pharmaceutics Vol. 178; no. 2; pp. 223 - 229
• Main Authors: Fredholt, Karin, Østergaard, Jesper, Savolainen, Jouko, Friis, Gitte Juel
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.02.1999; Elsevier
• Subjects: Biological and medical sciences; Chymotrypsin - chemistry; Cyclodextrin; Cyclodextrins - chemistry; Deamino Arginine Vasopressin - chemistry; Desmopressin (dDAVP); Dose-Response Relationship, Drug; Drug Interactions; Drug Stability; Enzyme kinetics; General pharmacology; Hormones. Endocrine system; Hydrogen-Ion Concentration; Hydrolysis; Medical sciences; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Phenylalanine - chemistry; Stability; α-Chymotrypsin; α-Chymotrypsin; Hydrolysis; Cyclodextrin; Stability; Enzyme kinetics; Desmopressin (dDAVP); Desmopressin; Pharmaceutical technology; Serine endopeptidases; Enzyme; Stabilization; Oligosaccharide; Chemical stability; Peptidases; Chymotrypsin; Enzymatic activity; Antidiuretic; Neurohypophyseal hormone; Enzymatic digestion; Dosage form; Hydrolases; Kinetics; Inclusion compound
• ISSN: 0378-5173; 1873-3476
• DOI: 10.1016/S0378-5173(98)00377-9

Desmopressin [1-(mercaptopropanoic acid)-8- d-arginine vasopressin; dDAVP] is a vasopressin analogue with a selective antidiuretic effect. The oral bioavailability of desmopressin is limited due both to its high hydrophilicity leading to a low intestinal permeability and to low enzymatic stability. The degradation of desmopressin was investigated in aqueous buffer solutions (pH 6.00–9.00) containing the enzyme α-chymotrypsin at a concentration of 0.50 mg/ml at 37°C. The degradation of desmopressin was also studied in solutions containing α-chymotrypsin in the concentration range 0.10–1.00 mg/ml (pH 7.40 and 37°C). The rate of degradation was shown to be highly dependent on both enzyme concentration and pH. Maximal α-chymotrypsin activity was observed in the pH range 7.40–8.00. It was observed that phenylalanine was formed during the degradation of desmopressin. Phenylalanine was formed in the amount of 20% in 120 min. In the same time period 95% of desmopressin was degraded. The formation of phenylalanine can be explained from the substrate specificity of α-chymotrypsin. Cyclodextrins are known to stabilize drugs including peptides against both chemical and enzymatic degradation. In this study it was shown that hydroxypropyl cyclodextrins (α, β and γ) stabilized desmopressin against α-chymotrypsin-catalyzed degradation. The stabilization was by a factor of 3, 9 and 8 at the concentration 12.5% (w/v) for hydroxypropyl-α-cyclodextrin, hydroxylpropyl-β-cyclodextrin and hydroxypropyl-γ-cyclodextrin.