Silicones in Cosmetics
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
Dimethicone (or dimethiconol) polymers differ from each other in the nature of the endgroup on the polymer chain. The CTFA or INCI designation does not differentiate between linear and branched polymers for either species, nor is polymer viscosity considered in this nomenclature system. Dimethicone is a nonreactive polymer characterized by a trimethylsilyl end-group, and is often referred to as a “capped” silicone polymer. Dimethiconol, on the other hand, is a reactive or uncapped polymer, and may undergo a self-condensation reaction during drying through the reactive hydroxyl or methoxyl endunits contained on the polymer chain. Both dimethicone and dimethiconol products may range from low-molecular-weight polydimethylsiloxane fluids (e.g., 1-cst fluids) to high-molecular-weight polymers (up to ) or silicone gums ( >40,000,000 cst). The most commonly employed dimethyl fluids have viscosities ranging from 100 to 300,000 cst, with the material of choice dependent upon the particular application. Blends of dimethicone gums in dimethicone fluids, or blends of fluids with differing viscosities, would all be classified by INCI designation as “dimethicone,’ with no regard for the number of species present. The same argument would apply for dimethiconol polymers.
Common Cosmetic Ingredients: Chemistry, Actions, Safety and Products
Heather A.E. Benson, Michael S. Roberts, Vânia Rodrigues Leite-Silva, Kenneth A. Walters in Cosmetic Formulation, 2019
Dimethicone is a mixture of siloxane polymers and can be used in creams at concentrations of up to 15% as a barrier agent. Dimethicone can prevent water loss across the skin and improve barrier thickness (Short et al., 2007). It also reduces melanin intensity, which may be an important part of photoaging, and improves dermatitis (Fowler, 2000). An extensive review of toxicity studies concluded that dimethicone and its variants were safe when used in cosmetic formulations (Nair, 2003).
Cosmetic camouflage for pigmentation issues
Dimitris Rigopoulos, Alexander C. Katoulis in Hyperpigmentation, 2017
Oil-free facial foundations contain no animal, vegetable, or mineral oils and are based on silicone derivatives, such as dimethicone. Dimethicone is an oil into which the pigment is dissolved. Water is in highest concentration, making this formulation a variant of the oil-in-water formulation previously discussed. Oil-free facial foundations are best for patients with oily or acne-prone skin who need camouflaging of very mild to mild dyspigmentation.
Permeation, stability and acute dermal irritation of miroestrol and deoxymiroestrol from Pueraria candollei var. mirifica crude extract loaded transdermal gels
Published in Pharmaceutical Development and Technology, 2021
Napaphak Jaipakdee, Kanokwan Jarukamjorn, Waraporn Putalun, Ekapol Limpongsa
Pueraria candollei var. mirifica (PM) ethanolic crude extract, containing 23.6 mg and 30.1 mg of miroestrol and deoxymiroestrol per gram of the crude extract, respectively, was provided by Professor Waraporn Putalun (Faculty of Pharmaceutical Sciences, Khon Kaen University, Thailand). Carbomer (Carbopol® 940), PEG-40 hydrogenated castor oil (NIKKOL HCO-40), caprylic/capric triglyceride (Tegosoft® CT) and triethanolamine were provided by Wanrat (Namsiang) (Thailand). Isopropyl myristate (IPM), sodium edetate, propylene glycol and tocopherol acetate were purchased from S. Tong Chemicals (Thailand). Silicone elastomer blend (Silicone CS-1600B (Dimethicone (and) dimethicone crosspolymer)) were received from Chem Sources (Thailand). Iscaguard® FPX (a blend of paraben esters, namely, methylparaben, ethylparaben, butylparaben, propylparaben and isobutylparaben in phenoxyethanol) was purchased from Chemipan Corporation Co., Ltd. (Thailand). Ethanol (95%) and polyethylene glycol 400 (PEG400) were purchased from Merck (Germany). Limonene was purchased from Fluka Analytical (USA). Transcutol® P (diethylene glycol monoethyl ether) was gifted from Rama Production (Thailand). Absolute ethanol, acetonitrile and methanol, HPLC grade, were purchased from RCI Labscan (Bangkok, Thailand). All of the components were used as supplied without further purification.
Preparation and evaluation of injectable Rasagiline mesylate dual-controlled drug delivery system for the treatment of Parkinson’s disease
Published in Drug Delivery, 2018
Ying Jiang, Xuemei Zhang, Hongjie Mu, Hongchen Hua, Dongyu Duan, Xiuju Yan, Yiyun Wang, Qingqing Meng, Xiaoyan Lu, Aiping Wang, Wanhui Liu, Youxin Li, Kaoxiang Sun
SAIB, Mw 856, specific gravity 1.146 kg L−1 at 25 °C, was obtained from Eastman Co., Ltd., St. Louis, MO, USA. Lakeshore® 7525 DLG 2 A (poly-d,l-lactide-co-glycolide, 75:25), Mw 14,000 Da, inherent viscosity 0.17 dL g−1 was purchased from SurModics Pharmaceuticals, Inc., Birmingham, AL, USA. RM (98%) was bought from Yancheng Langde Chemical Co., Ltd., Yancheng, China. Dimethicone, viscosity 350 cSt, was obtained from Dow Corning Corporation, Midland, MI, USA. Ethanol (EtOH), n-methylpyrrolidone (NMP), dichloromethane (CH2Cl2), and n-heptane were purchased from Sinopharm Chemical Reagent Co., Ltd., Shanghai, China. Span 80 was obtained from Nanjing Well Chemical Co., Ltd., Nanjing, China. Water was purified with a Milli-Q® (Bedford, MA, USA) filtration system, Millipore, USA. All other reagents and solvents were analytical grade.
Lipid depletion enables permeation of Staphylococcus aureus bacteria through human stratum corneum
Published in Tissue Barriers, 2020
Zachary W. Lipsky, Cláudia N. H. Marques, Guy K. German
Polydimethylsiloxane (PDMS) silicone elastomer (Sylgard 184, Dow Corning, Midland, MI) was prepared by mixing a 10:1 ratio of base to curing agent by weight. After mixing and degassing, the mixture was spin coated (WS-400B-6NNP/LITE, Laurell Technologies Corporation, North Wales, PA) on to a glass coverslip sequentially at 500, 1000, 1500, 3000, 5000, and 6000 rpm, each for 15 s. This produced a uniform silicone elastomer film 14 μm in thickness. Control and lipid depleted SC samples were alternately embedded in the uncured elastomer along the centerline of the coverslip, leaving only their outermost face exposed. This embedding process occludes the sides and underside of the SC sample, preventing bacterial growth in these regions. Substrates were then placed under vacuum in a vacuum desiccator (5310–0250, Nalgene®, ThermoFisher Scientific, Waltham, MA) with an attached vacuum pump (ME4 NT Vacuubrand, BrandTech, Essex, CT) for 4 hr to eliminate microbubbles between the SC and PDMS. The elastomer was then cured at room temperature and humidity for 48 hr. For each substrate tested, the order of the conditioned SC samples deposited was randomized.
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