Silica, colloidal anhydrous

Pantoprazole sodium was separately mixed in 1 1 ratios with sodium carbonate, mannitol, calcium stearate, colloidal anhydrous silica, povidone K90, crospovidone, and hydroxypropyl methylcellulose. The blends were stored at 40°C and 75% relative humidity, at 50°C and 75% relative humidity, and at 65°C for 30 days. No evidence for instability was noted, indicating that pantoprazole sodium is compatible with these common excipients. 

BP Colloidal anhydrous silica PhEur Silica colloidalis anhydrica USPNF Colloidal silicon dioxide... 

The most important incompatibility in capsules is the adsorption of active substances to excipients and vice versa. Sparingly water-soluble active substances may adsorb to non-water soluble excipients such as microcrystalline cellulose (diluent). On the other hand, the very fine glidant, colloidal anhydrous silica, can adsorb onto active substance particles. Especially for low dosed active substances, relatively large fractions may adsorb or be adsorbed. Such adsorption may delay the dissolution of the active substance, resulting in a delayed or incomplete release of the substance. This may lead to a reduced pharmaceutical availability and ultimately a lower therapeutic activity. Substances known to adsorb to microcrystalline cellulose are ethinylestradiol and dexamethasone [24]. 

Hydrochloithiazide 0.5-5 mg Acetone 2 x 3-5 mL for 15-150 mg hydrochlorthiazide 3 g diluent Mannitol with 0.5 % mA Colloidal anhydrous silica, compressed [33]... 

The phenytoin in Table 5.8 is a poorly wettable substance. Therefore it is mixed with colloidal anhydrous silica and subsequently triturated with sugar syrup. 

Triturate the nitrofurantoin macrocrystals with the colloidal anhydrous silica in a rough mortar... 

A special case is the use of an inorganic thickening agent in a 35 (or 50) % phosphoric acid dental etching gel (Table 7.9). In the strongly acidic environment of 35 % phosphoric acid only colloidal anhydrous silica can be used as a viscosity enhancer. 

Morphine sulphate in a matrix of a fatty base (Witepsol W25) with colloidal anhydrous silica (Aerosil R 972 ) and hydroxypropylmethylceUulose (HPMC 4000) [10] showed an absorption rate and a biological availability equivalent to orally given morphine sulphate retard tablets (MS Contin ). Such suppositories can be made as a regular pharmacy preparation [11] but in our opinion this requires more convincing evidence that morphine release is sufficiently reproducible. MS-Contm suppositories (not available in all countries) have a fatty base with sodium alginate and calcium phosphate [12]. 

Wetting of strongly hydrophobic active substances can be so difficult that the solid particles will not get dispersed properly and float on the water. Polysorbate 80 (0.1-0.15 %) can be added to the water to prevent this. Alternatively the solid active substance can be triturated with povidone or colloidal anhydrous silica, see Sect. 29.3. Addition of a surfactant such as polysorbate should be considered carefully, because unless in small amounts it may adversely affect the absorption comparable with the addition of surfactants to suppositories (see Sect. 11.3.2). 

Colloidal anhydrous silica (colloidal silicon oxide) and magnesium stearate are used as lubricants in the preparation of capsules, tablets and powders (see Sect. 4.4.3). Addition of lubricants in the preparation of capsules, powders and tablets usually leads to a smoother fill of the capsules, or the moulds. An additional advantage is the reduction of the losses as a result of the elimination of the static charge of the powder mixture. 

In the preparation of powders and capsules colloidal anhydrous silica (Aerosil ) is used as lubricant. There is a water containing and an anhydrous t3q>e Aerosil. There is discussion about the possibility that Aerosil causes silicosis. The occupational disease silicosis is as a result of long-term inhalation of siliceous dust. But in [5] it is concluded ... 

Inhalation of colloidal silicon dioxide dust may cause irritation to the respiratory tract but it is not associated with fibrosis of the lungs (silicosis), which can occur upon exposure to crystalline silica [5]. The main issue appears to be whether the silica is crystalline or not. Colloidal anhydrous silica Ph. Eur. is however amorphous. The irritation of the throat, eyes etc. is an issue though and because of lesser dust generation at weighing and processing the pressed anhydrous form (Aerosil 200 V ) is preferred. 

Lubricants can counteract the formation of agglomerates of small particles and disperse pre-existing agglomerates. Colloidal anhydrous silica is added for this purpose in the preparation of suppositories (see Sect. 11.4.6) and in the preparation of oral suspensions (see Sect. 5.4.6). 

British Pharmacopoeia (2009) Volume I and II monographs medicinal and pharmaceutical substances Colloidal Anhydrous Silica... 

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