Wax matrix formulations

Sugar-coated products have been marketed that contain KCl in a wax matrix (Slow-K and Kaon-Ct) and are purportedly slow- and controlled-release preparations. Available evidence indicates that these slow-release forms of KCl are occasionally capable of causing local tissue damage and therefore prol5ably should be used with caution for K+ supplementation. Solutions of potassium gluconate, like the tablets, also have been associated with intestinal ulceration. Microencapsulated KCl preparations Micro-K, K-Dur) that are neither enteric coated nor contained within a wax matrix appear to be superior to the wax matrix formulation. 

Glycerides and Polyglycolyzed Glycerides Most common carriers used in the preparation of sustained-release wax matrix formulations are glycerides and polyglycolyzed glycerides. There are several commercial... 

Emori, Ishizaka, and Koishi. formulated wax matrix tablets for prolonged drug release using a melt-congealing process. They studied the addition of acrylic acid polymer on the release of drug from a wax matrix consisting of carnauba wax and stearyl alcohol in a 1 1 ratio. 

Many solid-dosage forms of potassium chloride exist including tablets prepared by direct compression and granulation effervescent tablets coated, sustained-release tablets " sustained-release wax matrix tablets micro-capsules pellets and osmotic pump formulations. ... 

High localized concentrations of potassium chloride in the gastrointestinal tract can cause ulceration, hence the development of the many enteric-coated and wax matrix sustained-release preparations that are available.Although it is claimed that some formulations cause less ulceration than others, it is often preferred to administer potassium chloride as an aqueous solution. However, solutions have also been associated with problems, mainly due to their unpleasant taste. 

In this study, the influence of several formulation factors on the release kinetics of potassium chloride from directly compressed matrices is investigated. Formulations containing hydrophilic (methylcellulose, carbomer), plastic (polyvinyl chloride) and wax (glycerol palmitostearate) matrix materials at concentrations of 10%, 15% and 20%, and insoluble excipients, were prepared and tested using the USP XXI-NF XVI rotating paddle method. 

Research on the pyrolysis of thermoset plastics is less common than thermoplastic pyrolysis research. Thermosets are most often used in composite materials which contain many different components, mainly fibre reinforcement, fillers and the thermoset or polymer, which is the matrix or continuous phase. There has been interest in the application of the technology of pyrolysis to recycle composite plastics [25, 26]. Product yields of gas, oil/wax and char are complicated and misleading because of the wide variety of formulations used in the production of the composite. For example, a high amount of filler and fibre reinforcement results in a high solid residue and inevitably a reduced gas and oiFwax yield. Similarly, in many cases, the polymeric resin is a mixture of different thermosets and thermoplastics and for real-world samples, the formulation is proprietary information. Table 11.4 shows the product yield for the pyrolysis of polyurethane, polyester, polyamide and polycarbonate in a fluidized-bed pyrolysis reactor [9]. 

Mixture models (such as those of Scheffe) are still useful, especially when there are three or more such excipients with fairly large ranges of variation. In solid formulations, this is often the case for diluents (or fillers) and also for the polymers or waxes incorporated into controlled-release tablets to form a matrix through which the drug diffuses slowly out when immersed in aqueous fluid, i.e., in the gastrointestinal tract. 

Microcrystalline wax is also used in oral controlled-release matrix pellet formulations for various active compounds and as a tablet- and capsule-coating agent. In controlled-release systems, microcrystalline wax coatings can also be used to affect the release of drug from ion-exchange resin beads. Microcrystalline wax is also used in confectionery, cosmetics, and food products. 

These cationic SLN are formulated from a matrix lipid surfactants to stabilize the formulation and cationic lipids to charge the SLN surface positively. The cationic lipids employed are the same used in cationic liposomes for transfection [28]. Eormulation optimization studies revealed that both the cationic lipid and the matrix lipid influence transfection activity [27]. Comparable results were found for the oil component in cationic nanoemulsions for transfection [29]. Several formulations made from different cationic lipids and matrix lipids were tested for in vitro transfection efficiency (Eigure 6.8). The SLN Cp DOTAP made from the wax cetyl pahnitate and the cationic lipid N-[l-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium... 

Another configuration of diffusion-controlled systems includes matrix devices, which are common because of ease of fabrication. Diffusion control involves dispersion of drug in either a water-insoluble or a hydrophilic polymer. For instance, bupropion hydrochloride (Zyban , GlaxoSmithKline) is formulated using carnuba wax and hydroxypropylmethylcellulose. ... 

Forming an optimal molding may require the addition of an external or internal lubricant to the formulation. Lubricants arc added in only small amounts, up to 1 wt %. External lubricants are insoluble in the phenohe matrix resin and are often non- polar materials such as parafiins and waxes. External lubricants act as mold release agents. In contrast, internal lubricants improve melt homogeneity, lower viscosity, and lower injection pressure. Therefore, internal lubricants such as fatty alcohols, fatty acid salts, acid esters, and acid amides must be fully soluble in the phenohe prepolymer [1]. 

Microparticles. Size matters release rates depend on surface area, ie, a function of the square of the radius of a spherical particle, and thus larger particles release for longer and are able to manipulate the external availability of the pesticide. Small microparticles are therefore limited in their scope for controlling release but can be used in traditional spraying of dispersions onto soils and crops as well as for seed dressing. Suspension concentrate formulations of matrix microparticles have been developed based on various rosins, phenoUc resins, waxes, and bitumens. These have focused on lipophilic pesticides such as trifluralin and chlorpyrifos and reductions in volatility have been demonstrated (43). 

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