Silicon dioxide, colloidal

Figures 6 and 7 show the absorption spectra of colloidal CdS and ZnS at various times of illumination. The two colloids were prepared by adding an NaSH solution to solutions of Cd(C10j2 or Zn(C104)2, respectively, colloidal silicon dioxide (commercially available from Dupont Ludox HS30) being present at 6 x 10 M as stabilizer in both cases. The absorption starts in both cases close to the wavelengths that correspond to the photon energies (515 nm or 2.4 eV for CdS 340 nm or 3.7 eV for ZnS) at which the absorptions begin in the macrocrystalline materials. It is seen that illumination causes not only a decrease in the intensity of the absorption spectrum but also a change in the shape of the spectrum. The onset of light absorption is shifted towards...

The first observations on the fluorescence of colloidal CdS were made using a colloid stabilized by colloidal silicon dioxide . The fluorescence spectrum consisted of a broad band with the maximum between 580 nm and 650 nm. The reproducibility of this red fluorescence was very poor. In the presence of excess Cd ions the intensity of the fluorescence was increased, which indicates that anion vacancies were centers of luminescence. Aging of the sol for a few weeks in the dark and in the absence of air was accompanied by an increase in fluorescence intensity by a factor of ten and a gradual red shift of the fluorescence band. However, even after this increase, the fluorescence quantum yield was still below 10 . ... 

Calcium silicate Colloidal silicon dioxide Magnesium carbonate Magnesium trisilicate Starch Talc... 

An aqueous base is the least expensive vehicle and poses no toxicity problems. A solution of the drug in water or water and cosolvent is made. Glycerin, glycols, natural and synthetic gums, and/or polymers are used to increase viscosity, cohesiveness, and plasticity. To overcome syneresis, or water separation in the gel, a common problem with aqueous bases, one can use absorbing materials such as microcrystalline cellulose, kaolin, colloidal silicon dioxide, starch, etc. 

Excipients play a key role in oxidation, either as a primary source of oxidants, trace amounts of metals, or other contaminants. Auto-oxidation of diethylstilbes-terol to the peroxide and conjugated quinone degradation products was attributable to the presence of colloidal silicon dioxide, used as a glidant in solid oral dosage forms [48]. This was ascribed to the fact that silicon dioxide can act as a Lewis acid (an election acceptor or oxidising agent), under anhydrous conditions. 

Hahn, G. D. and Possmann, P. (1977). Colloidal silicon dioxide as a fining agent for wine. Am.. Enol. Vitic. 28,108-112. 

It was already noted that the presence of excessive moisture on the surface of pellets during spheronization could lead to uncontrolled agglomeration. This effect could be minimized by adding adsorbents like colloidal silicon dioxide or talc to the spheronizing pellets, increasing viscosity of binding fluid and complexing soluble materials in the mixture. As in... 

Glidants (e.g., colloidal silicon dioxide, talc) may need to be added to achieve desired flow properties, especially when the drug/filler ratio is relatively high. Usually, there is an optimum concentration of glidant for best flow, often less than 1% for the colloidal silicas (14,15). The following order of effectiveness of glidants has been reported for two powder systems fine silica > magnesium stearate > purified talc (16). 

Indeed, recently SEDDS themselves have been delivered as liquids absorbed onto powders such as colloidal silicon dioxide or microcrystalline cellulose (Nazzal et al., 2002). Selection of the absorbent was obviously critical to the performance of the system but, as an aside, it seems that this approach negates the rapid release properties of a SEDDS. It will be interesting to follow the future of this technology. 

Each 5 mL of VANTIN oral suspension contains cefpodoxime proxetil equivalent to 50 mg or 100 mg of cefpodoxime activity after constitution and the following inactive ingredients artificial flavorings, butylated hydroxy anisole, carboxymethylcellulose sodium, microcrystalline cellulose, carrageenan, citric acid, colloidal silicon dioxide, croscarmellose sodium, hydroxypropylcellulose, lactose, maltodextrin, natural flavorings, propylene glycol... 

Carafate suspension for oral administration contains 1 g sucralfate per 10 mL. Carafate suspension also contains colloidal silicon dioxide, FD C red no. 40, flavor, glycerin, methylcellulose, methylparaben, microcrystal-... 

Indicated for ripening and unfavorable Dinoprostone Prepidil Colloidal silicon dioxide, triacetin Aqueous... 

Colloidal silicon dioxide Tablet glidant Polysorbate 80 Surfactant... 

Catapres Clonidine HC1 USP 0.1, 0.2, 0.3 mg Tablet Hypertension Alpha-adrenoreceptor agonist Colloidal silicon dioxide, corn starch, dibasic calcium phosphate, gelatin, glycerin, lactose, magnesium stearate, methylparaben, propylparaben Boehriner Ingelheim (Mylan)... 

Mirapex Pramipexole 2HC1 0.125, 0.25, 0.5, 1 and 1.5 mg Tablet Parkinson s disease Nonergot dopamine agonist Mannitol, corn starch, colloidal silicon dioxide, povidone, magnesium stearate Boehriner Ingelheim... 

Risperdal Risperidone 0.25, 0.5, 1, 2, 3, 4 mg Tablet Schizophrenia A selective monoaminergic antagonist (5HT2, dopamine type 2 (D2), al and a2 adrenergic, and HI histaminergic receptors Colloidal silicon dioxide, hypromellose, lactose, magnesium stearate, MCC, propylene glycol, sodium lauryl sulfate, corn starch Janssen Pharmaceuticals... 

ProSom Estazolam 1, 2 mg Tablet Insomnia Lactose, povidone, colloidal silicon dioxide, stearic acid, sodium starch glucolate Abbott Laboratories... 

PLAN B Levonorgestrel 0.75 mg Tablet Emergency A synthetic Colloidal silicon dioxide, potato Barr Laboratories... 

Prosolv SMCC —silicified microcrystalline cellulose consisting of microcrystalline cellulose and colloidal silicon dioxide. 

The unit formula of example 3 is listed in Table 7.14. The batch size manufactured was 10 kg. The API was preblended with Avicel PH101 using a Patterson-Kelly tumble bin blender equipped with an intensifier bar (0.5 ft3, Fig. 7.6) at 15 rpm with the intensifier bar speed of 2000 rpm for 15 min. The preblend was mixed with lactose, sodium starch glycolate and colloidal silicon dioxide in a 1 ft3 tumble... 

Durasolv (CIMA Labs Inc.) Zomig ZMT Zolmitriptan (2.5mg), mannitol, microcrystalline cellulose, crospovidone, aspartame, sodium bicarbonate, citric acid, anhydrous, colloidal silicon dioxide, magnesium stearate, orange flavor Compression... 

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