Catherine Bulcourt, Benjamin Gavinet
Skin Forum 2022
Formulators often face challenges related to the APIs such as poor water solubility, targeted skin penetration or instability issues due to chemical structure. To solve these issues, formulation scientists have to use high quantities and/or a mix of solvents which can affect the stability, appearance or texture of the final product. Innovative inverse latex polymers allow formulation of chassis with high amounts of commonly used solvents such as PEG-400, diethylene glycol monoethyl ether, monopropylene glycol, glycerol or ethanol [1-2]. These rheology modifiers were theoretically designed to both thicken high concentrations of solvents and withstand the addition of all kind of oils to achieve more versatile dosage forms, in a wide pH range. The aim of this study was to assess the performance of these rheology modifiers, in practice, on the formulation of different semi-solid forms integrating solvents and oils in high amounts. The solvents selected were monopropylene glycol, glycerol, PEG-400, ethanol and diethylene glycol monoethyl ether used alone or as a mixture and combined with pharmaceutical oils such as mineral oils and ester. Among the semi-solid dosage forms, cream-gel (without added surfactant), O/W emulsion and gel-in-oil were explored. The selected solvents were studied alone and mixed together in growing quantities in cream-gel, gel-in-oil and emulsion with up to 30% of oils.. Stabilization of 25% diethylene glycol monoethyl ether and 30% mineral oil was achieved thanks to 2% of Acrylamide / Sodium Acryloyldimethyl Taurate Copolymer / Isohexadecane & Polysorbate 80. Formulation of this challenging composition in a cream-gel dosage form without further surfactant addition was not possible with other pharmaceutical polymers. Other specific advantages were highlighted (cold-process, texture improvement, …).
1 - Seppic, 50 boulevard National - CS 90020 - 92257 La Garenne Colombes, France