Mechanistic study of carvacrol processing and stabilization as glassy solid solution and microcapsule.
Essential oils and other liquid active pharmaceutical ingredients (APIs) are frequently microencapsulated to improve shelf life, handling, and for tailoring release. A glassy solid solution (GSS), a single-phase system, where the excipient is plasticized by the API, could be an alternative formulation system. Thus this study focuses on the investigation of two formulation strategies using carvacrol as a model compound, namely a microcapsule (MC) and a glassy solid solution (GSS). Applying the solubility parameter approach, polyvinylpyrrolidone (PVP) was chosen as a suitable matrix material for a GSS system, whereas maltodextrin and sucrose served as excipients for a microcapsule (MC) system. Differential scanning calorimetry (DSC) measurements of the excipients' glass transition temperatures and the melting point of carvacrol verified plasticizing properties of carvacrol on PVP. Batch mixing processes, as preliminary experiments for future extrusion processes, were performed to prepare GSSs and MCs with various amounts of carvacrol, followed by crushing and sieving. Maximally 4.5% carvacrol was encapsulated in the carbohydrate material, whereas up to 16.3% were stabilized as GSS, which is an outstanding amount. However, grinding of the samples led to a loss of up to 30% of carvacrol.
['Tackenberg|Markus W|MW|', 'Geisthövel|Carola|C|', 'Marmann|Andreas|A|', 'Schuchmann|Heike P|HP|', 'Kleinebudde|Peter|P|', 'Thommes|Markus|M|']
D002152:Calorimetry, Differential Scanning D002214:Capsules D002241:Carbohydrates D000081007:Cymenes D004355:Drug Stability D005079:Excipients D039821:Monoterpenes D011092:Polyethylene Glycols D011095:Polyethylenes D011109:Polymethacrylic Acids D011126:Polypropylenes D011205:Povidone D012996:Solutions D014867:Water
Carvacrol Glassy solid solution Microencapsulation Plasticization PVP Carbohydrates Carvacrol (PubChem CID: 10364) Maltodextrin (PubChem CID: 107526) Methylene chloride (PubChem CID: 66344) Polyvinylpyrrolidone (PubChem CID: 6917) Sodium hydroxide (PubChem CID: 14798) Sucrose (PubChem CID: 5988)