Chemical Modulation of Topical and Transdermal Permeation
Marc B. Brown, Adrian C. Williams in The Art and Science of Dermal Formulation Development, 2019
The mechanism for enhanced delivery from eutectic systems remains unclear. Naturally, the inclusion of an enhancer can modify the stratum corneum barrier properties as described previously. However, simply considering the melting point depression effect, at a gross level, it is clear that the lower melting point improves transdermal drug delivery, as predicted from the General Solubility Equation and shown experimentally for chiral compounds. In a eutectic mixture, the system has a lower melting point, but the permeant remains the original molecule of, for example, lidocaine. This parent molecule has the same properties as if in a simple saturated aqueous solution. Thus, the permeant melting point is not truly modified unless the permeant traverses the tissue with the counter molecule in the same proportion to the eutectic composition. Additionally, partitioning behaviour between the eutectic system and the skin probably affects permeation enhancement. However, by using a eutectic “liquid” saturated formulation, maximal thermodynamic activity in the donor phase can be maintained.
Structures and Properties of Self-Assembled Phospholipids in Excess Water
E. Nigel Harris, Thomas Exner, Graham R. V. Hughes, Ronald A. Asherson in Phospholipid-Binding Antibodies, 2020
When two phosopholipids are partially miscible in the gel phase and completely miscible in the fluid phase, the binary phase diagram may look like Figure 9B, which is for C( 18):C( 10)PC/C( 14):C( 14)PC mixtures.70 Such phase diagrams, constructed based on the onset and completion temperatures of phase transition curves obtained at various molar ratios of the mixtures, have a shape which is the hallmark of a eutectic system. In this system, there are three one-phase regions (G1, G2 and F), three two-phase regions (F + Gl5 F + G2 and Gi + G2), and one degenerated three-phase region, the eutectic point at a fixed temperature and composition. Of course, the three phases co-existing in equilibrium at the eutectic point are the maximum number of phases allowed to co-exist for the binary lipid mixtures, in excess water, at constant pressure according to the phase rule.66 In the case of C(18):C(10)PC/C(14):C(14)PC, the eutectic point is at 13.4°C and 40% of C(14):C(14)PC.
Piroxicam cocrystals with phenolic coformers: preparation, characterization, and dissolution properties
Published in Pharmaceutical Development and Technology, 2019
Shahram Emami, Khosro Adibkia, Mohammad Barzegar-Jalali, Mohammadreza Siahi-Shadbad
DSC can be used as a rapid and efficient method for cocrystal screening in the early stages (Lu et al. 2008). DSC screening has the ability to combine cocrystal formation and its analysis. In this technique, the thermal behavior of a physical mixture of a drug and coformer is investigated for the appearance of new endothermic and exothermic peaks. In the current study, the DSC thermograms of physical mixtures were analyzed based on the rules introduced by (Lu et al. 2008; Yamashita et al. 2014). These research groups have established two important characteristics of thermogram for binary mixtures capable of cocrystal formation. These rules are as follows: ‘(a) the physical mixture melting produces two peaks corresponding to the eutectic mixture and cocrystal melting (with their temperatures being different from the melting temperatures of individual components); (b) the eutectic melting (the first peak) is followed by a small exo-effect’ (Manin et al. 2014).
Assessment of toxic metal ions in tea samples using new microextraction technique based on the solidified deep eutectic solvent followed by GFAAS
Published in Toxin Reviews, 2021
Toraj Ahmadi-Jouibari, Negar Noori, Nazir Fattahi
Currently, cheap, affordable, and green extractants, called deep eutectic solvents (DESs), are being used as an alternative to ionic liquids and conventional organic solvents to extract trace amounts of organic and inorganic analytes (Bajkacz and Adamek 2018, Liu et al.2018, Malaeke et al.2018). DESs consist of two or three components that offer several environmental and economic advantages. These components form eutectic mixture having lowest melting point than each individual components and have the maximum capability to bound them self through hydrogen bonding (Rykowska et al.2018). DESs are formed mostly with the complexation of choline chloride with an inexpensive and nontoxic hydrogen bond donor or metal salts, such as urea, glycerol, carboxylic acid, sugar, etc. DESs not only have the advantages of low volatility, low vapor pressure, high thermal stability, and high ability to extract organic and inorganic compounds, but also have low cost and easy preparation of nontoxic compounds. Choline based DESs also overcome the health and safety challenges toward human and eco-toxicity issues.
Synthesis and characterization of meloxicam eutectics with mandelic acid and saccharin for enhanced solubility
Published in Drug Development and Industrial Pharmacy, 2020
Richard Perosa Fernandes, Ana Carina Sobral de Carvalho, Bruno Ekawa, Andre Luiz Soares Carneiro do Nascimento, Andressa Maria Pironi, Marlus Chorilli, Flávio Junior Caires
MND and SAC were able to form eutectic mixtures with MLX by LAG method. Tamman’s triangle and binary phase diagram suggest the optimum eutectic composition of 0.33 molar fraction of MLX for SAC and MND. Eutectics solubility is higher at 24 h when compared with pure MLX with a slow dissolution rate until 480 min. MLX-MND2 eutectic presents the highest solubility at 24 h and hygroscopicity at day 4 compared to all samples. Thermal behavior changes from eutectic to MLX, with distinct melting, evaporation, and degradation that are viewed by video and analyzed by TG-DSC and DSC curves. Spectroscopic techniques and thermal analysis help to identify a new polymorphic form in eutectic mixture. The study helps to understand and explore eutectic mixtures from its formation until the application as a tool to modify solubility and dissolution rate in drugs.
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