title: Photostabilization of papaverine hydrochloride solutions.
abstract: Abstract: The stability of aqueous and non-aqueous papaverine hydrochloride solutions exposed to the UV radiation is poor. In order to enhance its photo-stability suitable light absorbers may be used. There werefour photo-protectors considered in this work: 4-aminobenzoic acid, sodium benzoate, methyl 4-hydroxybenzoate and propyl 4-hydroxybenzoate, whose UV absorption spectra characteristics match to some extent with the UV spectrum of papaverine. Approximately 20 mg/mL papaverine chloroform solutions with the above non-toxic additives in the concentrations 0.01; 0.05; 0.10% were exposed to the UV light of 254 nm. High performance capillary electrophoresis was used to determine the papaverine hydrochloride concentration loss as a function of time exposition to the light. It was found that papaverine hydrochloride photolysis proceeds according to the first-order kinetics. Methyl 4-hydroxybenzoate was found to be the best UV radiation-protective agent, and at the concentration 0.10%, the reaction rate constant decreases from 0.143 h(-1) to 0.028 h(-1). Both 4-hydroxybenzoate esters develop a more efficient UV radiation-protective activity than sodium benzoate, because the latter additive molar extinction coefficient is less significant. However, in spite of a high value of 4-aminobenzoic acid molar absorptivity coefficient, it is an unsuitable photo-protector for papaverine hydrochloride solutions, because its UV absorption spectrum does not match with that of papaverine.
authors.affiliation: Department of Physical Pharmacy and Pharmacokinetics, Poznań University of Medical Sciences, 6 Swiecickiego St., 60-781 Poznań, Poland.
authors.forename: Karolina
authors.initials: K
authors.lastname: Piotrowska
authors.forename: Tadeusz W
authors.initials: TW
authors.lastname: Hermann
authors.forename: Alicja
authors.initials: A
authors.lastname: Pawelska
mesh_terms: D002138:Calibration; D053801:Capillary Electrochromatography; D002725:Chloroform; D004355:Drug Stability; D005079:Excipients; D007202:Indicators and Reagents; D007700:Kinetics; D010084:Oxidation-Reduction; D010208:Papaverine / Q000737:chemistry*; D019999:Pharmaceutical Solutions; D010777:Photochemistry; D012997:Solvents; D013056:Spectrophotometry, Ultraviolet
chemical_list: D005079:Excipients; D007202:Indicators and Reagents; D019999:Pharmaceutical Solutions; D012997:Solvents; D002725:Chloroform; D010208:Papaverine