Thermal behavior and kinetic study of degradation for adamantan-2-one versus memantine hydrochloride Ma ˘da ˘lina Mateescu 1 • Mihaela Budiul 1 • Paul Albu 1,2 • Gabriela Vlase 3 • Titus Vlase 1 Received: 14 December 2016 / Accepted: 4 May 2017 Ó Akade ´miai Kiado ´, Budapest, Hungary 2017 Abstract Adamantan-2-one is an adamantane derivative used as a precursor for different adamantane-based phar- macologically active compounds. Adamantan-2-one and memantine hydrochloride were investigated in other of our previous published papers, as pure compounds and in binary mixtures with various excipients. The aim of our study is to determine the thermal behavior of adamantan-2- one, as well as the kinetic parameters that characterize the degradation process of this precursor. The employed ana- lytical techniques were thermal analysis (TG/DTG/HF) and FTIR spectroscopy. The TG/DTG/HF curves were recor- ded in air at different heating rates: b = 5, 7, 10, 12 and 15 °C min -1 , in respect of the ICTAC 2000 protocol regarding the kinetic analysis. The methods used for kinetic analysis of the thermal degradation process were isocon- versional methods: Friedman and Flynn–Wall–Ozawa. Modified NPK method was used for determination of kinetic parameters. Keywords Adamantane-2-one  FTIR  Thermal stability  Non-isothermal kinetics  Kinetic analysis  Modified NPK method Introduction Nowadays the drugs based on 2-substituted adamantanes have attracted significant interest. Due to the number of methods of direct oxidation of adamantane to adamantan- 2-one (Ada) or 2-oxo-tricyclo[3.3.1.1 3,7 ]decane (Fig. 1), the last compound is often used as a precursor in the synthesis of different biological active substances [1]. Ada and drug memantine hydrochloride (Mem) are two substances that contain the bridged tricyclic adamantane structure. The difference occurs regarding their functional groups: Ada has an oxo group, while memantine has an amino group and two methyl side chains [2, 3]. The development of stable medicinal compounds requires to study the initial substances, intermediates and the target compound [1]. Thermal analytical techniques are very often used to provide information about storage and stability of pharmaceuticals [3]. Thermal stability for drugs and for drug-excipient mixtures is important to elucidate incompatibility and to know the thermal behavior. Also these data can offer very important information about the stability of the organic molecule [3]. The objective of this study was to use TG/DTG and HF data to investigate the thermal behavior and decomposition kinetics of Ada. Isoconversional methods Friedman and Flynn–Wall–Ozawa were used for kinetic analysis, and mod- ified NPK was used for determination of kinetic parameters. The thermal analysis and data processing strategy were similar to some of our previous studies regarding Ada and Mem [2, 3]. & Titus Vlase titus.vlase@e-uvt.ro 1 Research Center: Thermal Analysis in Environmental Problems, West University of Timisoara, 16 Pestalozzi Street, 300115 Timis ¸oara, Romania 2 Department of Pharmaceutical Sciences, Faculty of Pharmacy, ‘‘Vasile Goldis’’ West University of Arad, 86 L. Rebreanu St., 310414 Arad, Romania 3 Faculty of Pharmacy, University of Medicine and Pharmacy ‘‘Victor Babes ¸’’, 2 EftimieMurgu Square, 300041 Timis ¸oara, Romania 123 J Therm Anal Calorim DOI 10.1007/s10973-017-6443-9