Lactose coating

Fernandez-Arevalo, M. Vela, M.T. Rabasco, A.M. Rheological study of lactose coated and acrylic resins. Drug Dev. Ind. Pharm. 1990, 16 (2), 295-313. 

Pharmaceutical tablets coated with lactose often develop a brown discoloration. The factors that primarily affect the... 

Zhou, Q., Armstrong, B., Larson, I., Stewart, P. J., Morton, D. A. V. Improving powder flow properties of a cohesive lactose monohydrate powder by intensive mechanical dry coating. J. Pharm. Sci., 99, 2010, 969-981. 

Spherical pellets containing 5% triamcinolone acetonide were prepared by Villar-Lopez and co-workers [59] by extrusion/spheronization following formulation with microcrystalline cellulose and/or a hydrophilic excipient like lactose, sodium earbox-ymethylcellulose, or P-cyclodextrin. Their suitability for coating, with a view toward colonic drug deliveiy, was assessed in terms of their size, sphericity, and dissolution test response. The best results were afforded by a 5 90 5 composition of microcrystalline cellulose, P-cyclodextrin, and triamcinolone acetonide, prepared by complex-ation of triamcinolone acetonide with P-cyclodextrin prior to the addition of microcrystalline cellulose. 

The verapamil pellets contained equal parts of verapamil hydrochloride (Fermion) and lactose (Ph. Eur.) plus 4% of gelatin as a binder. They were coated using a fluidized bed technique (Aeromatic Strea 1, Aeromatic AG). The coat consisted of ethyl cellulose (Ethocel N-50), Hercules) and 20% of dibutyl sebacate (E. Merck) as a plasticizer. The calculated amount of coating in the pellets was 10%. The density of the verapamil pellets was 1.13. The in vitro dissolution pattern was determined according to the USP paddle method 50% of the drug was dissolved at 4.2 h. 

Controlled optimal particle size and size distribution ensures superior flow properties of coprocessed excipients and reduced reliance on addition of glidants. The volumetric flow properties of SMCC were studied in comparison with those of the physical mixture of its parent excipients (42). The particle size range of the two test samples was found to be similar, but the flow of coprocessed excipient was better than that of the physical mixture. A comparison of the flow properties of Cellactose with its parent excipients was also performed (5) by measuring the angle of repose and Hausner ratio, and Cellactose was found to have better flow characteristics than lactose or a physical mixture of cellulose and lactose. The spray-dried coprocessed product had a spherical shape and even surfaces, which resulted in improved flow properties. On similar terms, mechanically coating the 2% CSD over microfine cellulose powder resulted in improving its flow properties (43). 

Chan LW, Lim LT, Heng PW. Immobilization of fine particles on lactose carrier by precision coating and its effect on the performance of dry powder formulations. J Pharm Sci 2003 92(5) 975-984. 

Lactitol. Lactitol (4-0-/ -D-galactopyranosyl-D-sorbitol), is a synthetic sugar alcohol produced on reduction of lactose, usually using Raney nickel. It can be crystallized as a mono- or di-hydrate. Lactitol is not metabolized by higher animals it is relatively sweet and hence has potential as a non-nutritive sweetener. It is claimed that lactitol reduces the absorption of sucrose, blood and liver cholesterol levels and to be anticariogenic. It has applications in low-calorie foods (jams, marmalade, chocolate, baked goods) it is non-hygroscopic and can be used to coat moisture-sensitive foods, e.g. sweets. 

Other systems make use of the sticking tendency of acid whey. Partially dried whey powder coats the inner wall of the drying chamber, whence it falls when the crystalline lactose content of the powder becomes high. However, sticking of the product on the hot metal surfaces can be a problem unless sufficient moisture is present so that lactose crystallization proceeds to the point where the powder no longer adheres to the equipment (Pallansch 1973). 

Lactose in the glass state may be used as a protective coating on certain materials, either to seal in components or to protect the material from the environment. Materials may be coated with lactose solution and dried, or a solution containing the material and lactose can be spray-dried. This latter application has been used to preserve enzymatic activity during spray drying and storage (Nickerson 1974). 

Sharma et al. [44] Lactose Milk and dairy products Lactase and galactose oxidase (GaO)/in Langmuir-Blodgett (LB) films of poly(3-hexyl thiophene) (P3HT)/stearic acid (SA) Indium-tin-oxide coated glass plates/0.4 V vs. Pt reference electrode ... 

Part of the process to make cheese involves the flocculation of an electrostatically stabilized colloidal O/W emulsion of oil droplets coated with milk casein. The flocculation is caused by the addition of a salt, leading to the formation of networks which eventually gel. The other part of the process involves reaction with an enzyme (such as rennet), an acid (such as lactic acid), and possibly heat, pressure and microorganisms, to help with the ripening [811]. The final aggregates (curd) trap much of the fat and some of the water and lactose. The remaining liquid is the whey, much of which readily separates out from the curd. Adding heat to the curd (-38 °C) helps to further separate out the whey and convert the curd from a suspension to an elastic solid. There are about 20 different basic kinds of cheese, with nearly 1000 types and regional names. Potter provides some classification [811]. 

Fig. 15 Specific protein separation by a smart thermoresponsive polymer coating. Left PNIPAM with immobilized lactose and RCA 120 is below the LCST. The moieties are separated and, therefore, proteins from the mobile phase can bind to RCA120. Right PNIPAM below LCST. Polymer-bound lactose and RCA120 come into close contact and lactose displaces the protein. Reprinted, with permission, from [194]. Copyright (2003) American Chemical Society...

Like many other herbal extracts, valerian extract is very hygroscopic. Inclusion into tablets raises stability issues. Coatings reduce moisture absorption but often lead to tablet explosion or visual deterioration (black specs). Tablets formulated with 250 mg valerian extract, spray-dried lactose, and compressible starch were... 

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