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PubMedDate not supplied

Development and evaluation of sustained-release propranolol wax microspheres.

To obtain a sustained-release dosage form with a lack of gastric unwanted effects, wax microspheres containing propranolol (I) were prepared by a congealable dispersion microencapsulation technique. The effects of the process variables; type of wax, speed of emulsification, amount of drug loaded, type and amount of emulsifier, were studied on the entrapment efficiency, angle of repose, dissolution efficiency (DE), in-vitro drug release and mean particle size of (I) microspheres, by a factorial design. The results showed that changes in the amount of emulsifier (Tween), 0.04% and 0.08%, the type of Tween (80 and 20) and the wax type; beeswax or ceresine, caused a significant decrease in the entrapment efficiency. All the variables had an effect on the angle of repose and particle size of the (I) microspheres. The only significant parameter affecting the DE was the nature of the wax. The drug release in pH 6.8 was affected by all the variables except the amount of emulsifier. The formulation with a 0.25:4 ratio of drug:ceresine wax and 0.04% of Tween 80 in 600 rpm emulsification speed showed a suitable multiparticulate delivery system for the retarded dissolution of entrapped active ingredients, allowing absorption only in the intestinal tract.

Adrenergic beta-Antagonists↗
PubMed2003

Melt granulation and heat treatment for wax matrix-controlled drug release.

The purpose of this study was to evaluate sustained drug release after melt granulation and heat treatment. Theophylline (anhydrous) and phenylpropanolamine hydrochloride (PPA) were used as model drugs. Compritol 888 ATO (Glyceryl Behenate NF) was incorporated as the wax matrix material. Formulations with drug:wax in 3:1 and 1:1 ratios were evaluated. Tablets were made by dry blending or melt granulation; some of the tablets were heat treated at 80 degrees C for 30 min. Tablets with or without heat treatment were tested for drug release using in vitro drug dissolution. The results showed that melt granulation gave slower drug release than dry blending. Heat treatment further retarded drug release for both dry blending and melt granulation. The drug release rates for theophylline were slower than for PPA at the same wax level and processing method. The drug release profiles were linear using a square root of time scale. In conclusion, melt granulation and heat treatment slowed drug release for the wax matrix-controlled release tablets. Heat treatment of the tablets made by melt granulation further retarded drug release. Heat treatment redistributed the wax, forming a new matrix system with higher tortuosity. The application of melt granulation or heat treatment can successfully retard drug release.

Chemistry, Pharmaceutical↗
PubMed2005

Calculation of the store house worker dose in a lost wax foundry using MCNP-4C.

Lost wax casting is an industrial process which permits the transmutation into metal of models made in wax. The wax model is covered with a silicaceous shell of the required thickness and once this shell is built the set is heated and wax melted. Liquid metal is then cast into the shell replacing the wax. When the metal is cool, the shell is broken away in order to recover the metallic piece. In this process zircon sands are used for the preparation of the silicaceous shell. These sands have varying concentrations of natural radionuclides: 238U, 232Th and 235U together with their progenics. The zircon sand is distributed in bags of 50 kg, and 30 bags are on a pallet, weighing 1,500 kg. The pallets with the bags have dimensions 80 cm x 120 cm x 80 cm, and constitute the radiation source in this case. The only pathway of exposure to workers in the store house is external radiation. In this case there is no dust because the bags are closed and covered by plastic, the store house has a good ventilation rate and so radon accumulation is not possible. The workers do not touch with their hands the bags and consequently skin contamination will not take place. In this study all situations of external irradiation to the workers have been considered; transportation of the pallets from vehicle to store house, lifting the pallets to the shelf, resting of the stock on the shelf, getting down the pallets, and carrying the pallets to production area. Using MCNP-4C exposure situations have been simulated, considering that the source has a homogeneous composition, the minimum stock in the store house is constituted by 7 pallets, and the several distances between pallets and workers when they are at work. The photons flux obtained by MCNP-4C is multiplied by the conversion factor of Flux to Kerma for air by conversion factor to Effective Dose by Kerma unit, and by the number of emitted photons. Those conversion factors are obtained of ICRP 74 table 1 and table 17 respectively. This is the way to obtain a function giving dose rate around the source.

Body Burden↗
PubMed1980

Detection of castor allergens in castor wax.

The presence of castor bean allergens in castor wax products was determined by in vivo and in vitro analysis of castor wax extracts. Allergens were detected in one extract of castor wax by the PCA reaction in mice, the RAST inhibition reaction, and skin prick test in castor bean sensitive individuals. However, these allergens in the wax were of much lower potency than those in the bean, and were not detectable in a deodorant product utilizing castor wax.

Allergens↗
PubMed2006

The effects of stress on plant cuticular waxes.

Plants are subject to a wide range of abiotic stresses, and their cuticular wax layer provides a protective barrier, which consists predominantly of long-chain hydrocarbon compounds, including alkanes, primary alcohols, aldehydes, secondary alcohols, ketones, esters and other derived compounds. This article discusses current knowledge relating to the effects of stress on cuticular waxes and the ways in which the wax provides protection against the deleterious effects of light, temperature, osmotic stress, physical damage, altitude and pollution. Topics covered here include biosynthesis, morphology, composition and function of cuticular waxes in relation to the effects of stress, and some recent findings concerning the effects of stress on regulation of wax biosynthesis are described.

Humidity↗
PubMed1996

Accuracy of wax, autopolymerized, and light-polymerized resin pattern materials.

PURPOSE: The marginal fit of MOD inlay and full-crown patterns fabricated from wax, autopolymerized acrylic resin, and two light-polymerized, diacrylate resin pattern materials was compared on standardized dies. MATERIALS AND METHODS: Four pattern materials were studied-two light-polymerized, diacrylate resin materials (Palavit G LC and Triad VLC Burnout Paste), an inlay wax, and an autopolymerized resin (Duralay). Patterns were fabricated using incremental and bulk techniques on stone dies made from addition silicone impressions of American Dental Association MOD and full-crown master dies. Gaps were measured with a measuring microscope in four marginal areas on the master dies at 1 and 24 hours after fabrication. RESULTS: For the MOD inlay patterns, marginal gaps ranged from 7 to 23 microns, and the light-polymerized, diacrylate resins and autopolymerized acrylic resin material had statistically smaller gaps than the inlay wax. For the full-crown patterns, marginal gaps ranged from 10 to 23 microns, with the exception of the autopolymerized acrylic resin prepared by the bulk technique (40 to 46 microns). With the incremental technique, the light-polymerized, diacrylate resins and inlay wax had statistically smaller gaps than the autopolymerized acrylic resin material. Overall, the incremental technique produced equal or smaller marginal gaps than the bulk technique for full-crown patterns. Generally, the patterns measured at 1 hour had smaller marginal gaps than at 24 hours. CONCLUSIONS: When measured on intra- and extracoronal master dies, the light-polymerized, diacrylate resins had equal or better marginal fit, compared with wax or autopolymerized acrylic resin, and were less affected by placement technique and storage. The marginal gaps of all four pattern materials ranged from 7 to 46 microns and are within the range of clinical acceptability.

Acrylic Resins↗
PubMed1967

Leaf epicuticular waxes.

The external surface of the higher plants comprises a cuticular layer covered by a waxy deposit. This deposit is believed to play a major part in such phenomena as the water balance of plants and the behavior of agricultural sprays. The wax contains a wide range of organic compounds. These complex mixtures are amenable to modern microchromatographic and microspectrometric analytical procedures. The few surveys which have been made of the species distribution of certain classes of constituents indicate that such distribution may be of limited taxonomic value; however, the wax composition of a species may differ for different parts of the same plant and may vary with season, locale, and the age of the plant. This fascinating subject, in which the disciplines of botany, biochemistry, chemistry, and physics overlap and interact, is still in a very active state. Much remains to be learned about the composition and fine structure of the wax deposits, and, for this, experimental study of wax crystallization and permeation through artificial membranes will be required. Enzymic studies, radiolabeling, and electron microscopy will be needed to reveal the mode of biogenesis of the wax constituents and their site of formation and subsequent pathway through the cuticle to the leaf surface.

Aldehydes↗
PubMed1990

Movement of wax particles by contractions in the isolated opossum esophagus.

We investigated whether the contractions of the isolated smooth muscle opossum esophagus can propel luminal contents. Wax particles were placed into the esophagus in vitro, and esophageal contractions were evoked by stimulating either primarily the intrinsic esophageal nerves (using electrical pulses of 0.5 ms) or the esophageal muscle directly (using pulses of 0.5 s). Direct muscle stimulation and neural stimulation produced circular muscle contractions of similar amplitude, but only neural stimulation was associated with a propagating ring contraction and longitudinal muscle contraction. Movement of the wax particle occurred after 21% of all stimulus responses. Aborad movement of the wax particle was 10 times as common as was its orad movement. Wax movement occurred less commonly and over shorter distance with muscle as compared with neural stimulation. The distance the wax moved was enhanced when the esophagus was allowed to shorten in its longitudinal axis. Movement occurred late during the contraction response and at velocities less than that of the ring contraction. Also, the ring contraction passed over the particle. The amplitude of circular muscle contractions had no predictive value for the occurrence of propulsion. The finding that the isolated esophagus can propel luminal contents in the aborad direction supports the thesis that peristalsis is primarily a function of the intrinsic neuromuscular organization of the smooth muscle esophagus.

Animals↗
PubMedDate not supplied

Ninety-day feeding study in Fischer-344 rats of highly refined petroleum-derived food-grade white oils and waxes.

Subchronic 90-day feeding studies were conducted in male and female Fischer-344 (F-344) rats on highly refined white mineral oils and waxes representative of those used for food applications. The goal was to help clarify the mixed results found in other toxicity studies with laboratory animals. Seven white oils and 5 waxes were fed at dietary doses of 20,000, 2,000, 200, and 20 ppm and compared with control groups on untreated diet; toxicity was assessed at 90 days and also after a reversal period of 28 days and/or 85 days. Higher molecular-sized hydrocarbons (microcrystalline waxes and the higher viscosity oils) were without biological effects. Paraffin waxes and low- to midviscosity oils produced biological effects that were inversely related to molecular weight, viscosity, and melting point; oil type and processing did not appear to be determinants. Biological effects were more pronounced in females than in males. Effects occurred mainly in the liver and mesenteric lymph nodes and included increased organ weights, microscopic inflammatory changes, and evidence for the presence of saturated mineral hydrocarbons in affected tissues. Inflammation of the cardiac mitral valve was also observed at high doses in rats treated with paraffin waxes. Further studies are required to elucidate the mechanism for the responses observed and the relevance of these inflammatory responses in the F-344 rat to other species, including humans.

Animals↗
PubMed2002

Release from or through a wax matrix system. IV. Generalized expression of the release process for a reservoir device tablet.

Generalization of the release process through the wax matrix layer was examined by use of a reservoir device tablet. The wax matrix layer of the reservoir device tablet was prepared from a physical mixture of lactose and hydrogenated castor oil to simplify the release properties. Release through the wax matrix layer showed zero-order kinetics in a steady state after a given lag time, and could be divided into two stages. The first stage was the formation process of water channel by dissolving the soluble component in the wax matrix layer. The lag time obtained by applying the square root law equation was well connected with the amount of the matrix layer and mixed weight ratio of components in this layer. The second stage was the zero-order release process of drug in the reservoir through the wax matrix layer, because the effective surface area was fixed. The release rate constants were connected with thickness of the matrix layer and permeability coefficient, and the permeability coefficients were connected with the diffusion coefficient of drug and porosity. Hence the release rate constant could be connected with the amount of matrix layer and the mixed weight ratio of components in the matrix layer. It was therefore suggested that the release process could be generalized using the amount of matrix layer and the mixed weight ratio of components in the matrix layer.

Algorithms↗
PubMed2003

Optimum heat treatment conditions for masking the bitterness of the clarithromycin wax matrix.

The effects of the contents of aminoalkyl methacrylate copolymer E (AMCE) in a wax matrix on the mechanism of polymorphic transformation of glyceryl monostearate (GM) were clarified by evaluating the enthalpy change defined as 1.51 (DeltaH(1)-DeltaH(2))/DeltaH(2), where DeltaH(1) and DeltaH(2) denote the enthalpies in the first and second thermal analyses, respectively. Using this value, K(1), the rate constant of transformation from alpha-form to beta'-form, and K(2), the rate constant of transformation from beta'-form to beta-form, could be obtained. As the ratio of AMCE increased, K(2) increased, but a minimum point existed for K(1). K(1) was always larger than K(2), but gradually approached K(2) as the ratio of AMCE increased. The optimum temperature for the transformation of GM was 50 degrees C, at which the enthalpy change was maximum. To prepare the wax matrix preparation of clarithromycin (CAM), we considered 40 degrees C the optimum treatment temperature for the transformation of GM in a CAM wax matrix compounded from CAM, GM and AMCE, since the matrices were mutually welded at above 45 degrees C during the spray congealing process. Although K(1) and K(2) were almost the same at 40 degrees C, the rate of transformation was accelerated by tumbling. By applying the tumbling that accelerated the transformation of GM in a CAM wax matrix, almost all of the alpha-form disappeared, and the release of CAM from the wax matrix diminished when the enthalpy change was more than 0.8.

Algorithms↗
PubMedDate not supplied

Major constituents of the foliar epicuticular waxes of species from the Caatinga and Cerrado.

The epicuticular waxes of leaves of four species (Aspidosperma pyrifolium, Capparis yco, Maytenus rigida and Ziziphus joazeiro) from the Caatinga, (a semi-arid ecosystem of Northeast Brazil) and four species (Aristolochia esperanzae, Didymopanax vinosum, Strychnos pseudoquina and Tocoyena formosa) from the Cerrado, (a savanna ecosystem covering one third of the Brazilian territory), were analyzed. Six species contained a high content (above 60 microg x cm(-2)) of wax, four of them from the Caatinga. Triterpenoids and n-alkanes were the most frequent and abundant constituents found in the species from both habitats. The distribution of n-alkanes predominated by homologues with 27, 29, 31 and 33 carbon atoms, displayed no consistent differences between species from the two habitats. Lupeol, beta-amyrin, epifriedelinol and ursolic acid were the triterpenoids found. Triterpenoids clearly predominate over alkanes in the waxes from the Cerrado species. The waxes of two evergreen species from the Caatinga yielded n-alkanes as predominant constituents. A comparison of foliar epicuticular waxes of native plants from ecosystems with different hydric constraints is discussed.

Alcohols↗
PubMedDate not supplied

Cuticular waxes and flavonol aglycones of mistletoes.

Cuticular waxes of Viscum album subspecies and of V. cruciatum have been examined for their micromorphology and chemical composition. Wax crystalloids occur preferably as irregular platelets and rodlets, while deviant structures are found in small areas. Among the triterpenoids forming the wax layer, oleanolic acid is prevailing with some 80%. The quantitative composition of the long-chain aliphatics, which comprise several classes, is rather variable. Flavonoid aglycones, occurring as very minor components of the cuticular waxes, comprise the flavonols kaempferol and quercetin and a series of their methyl derivatives, in some taxa also the flavanone naringenin. Neither the crystalloid structures nor the chemical composition of the wax allow to discriminate the 2 species, or male and female plants, or plants grown on conifers or on dicotyledoneous hosts.

Alcohols↗
PubMedDate not supplied

Chemical, dissolution stability and microscopic evaluation of suspensions of ibuprofen and sustained release ibuprofen-wax microspheres.

Chemical stability studies of suspensions of ibuprofen powder and ibuprofen-wax microspheres were performed using an accelerated stability protocol with a modified high performance liquid chromatography (HPLC) procedure. The variables considered were pH, suspending agents and temperature. The study showed little or no chemical degradation in the different suspending agents after storage for three months. Dissolution stability was examined in suspensions of ibuprofen microspheres made from an optimized formulation with 17% drug loading. The storage temperature were 23, 37 and 45 degrees C. Other variables for the dissolution stability studies were suspending agents, wax types, suspending medium pH and microsphere size. Suspensions of ceresine wax microspheres stored at 37 degrees C showed faster drug release than room temperature storage, but suspensions stored at 45 degrees C showed an opposite effect. Microspheres suspended in syrup and stored at 37 degrees C had faster dissolution rates than microspheres suspended in methylcellulose at the same temperature, possibly as a result of an interaction between the syrup and the microsphere constituents. Suspensions of microcrystalline wax microspheres had better dissolution stability than microspheres made from ceresine wax. Higher suspending medium pH resulted in faster release of drug from the suspended microspheres, but particle size did not significantly affect the dissolution stability.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2006

[Analysis of constituents in urushi wax, a natural food additive].

Urushi wax is a natural gum base used as a food additive. In order to evaluate the quality of urushi wax as a food additive and to obtain information useful for setting official standards, we investigated the constituents and their concentrations in urushi wax, using the same sample as scheduled for toxicity testing. After methanolysis of urushi wax, the composition of fatty acids was analyzed by GC/MS. The results indicated that the main fatty acids were palmitic acid, oleic acid and stearic acid. LC/MS analysis of urushi wax provided molecular-related ions of the main constituents. The main constituents were identified as triglycerides, namely glyceryl tripalmitate (30.7%), glyceryl dipalmitate monooleate (21.2%), glyceryl dioleate monopalmitate (2.1%), glyceryl monooleate monopalmitate monostearate (2.6%), glyceryl dipalmitate monostearate (5.6%), glyceryl distearate monopalmitate (1.4%). Glyceryl dipalmitate monooleate isomers differing in the binding sites of each constituent fatty acid could be separately determined by LC/MS/MS.

Chromatography, Liquid↗
PubMed1992

Base plate wax, dimensional stability and sorption of active components following treatment with disinfectant solutions.

The influence of seven disinfectants on the dimensional stability of a base plate wax, Tenax, was studied. Two methods for treatment were tested - immersion for one hour and spraying respectively. After spraying no significant influence on the wax could be established and after immersion four of the seven disinfectants, including Cidex and K-644, likewise had no significant influence on the dimensional stability. The wax specimens did not show any significant weight increase (less than one per cent) after immersion for four days but in four disinfectant solutions the surface properties of the wax specimens had changed showing that active components of the disinfectants were absorbed into or adsorbed on the wax surface.

Absorption↗
PubMedDate not supplied

Wax therapy for dry feet in leprosy.

A comparative study of the effect of wax therapy and foot soaks on dry plantar skin was conducted in patients with leprosy. Thirty patients with varying grades of fissures and callosities were given wax therapy for feet, and 20 similar patients were given foot soaks. Patients given wax therapy felt subjectively much better than those who had soaking. Healing of cracks and fissures and softening of callosities was observed more frequently in patients with wax therapy. These differences are statistically significant. As an institutional method wax therapy has definite advantages for treating patients with fissures and callosities, whereas soaking of the feet is easy and readily available in patients' homes to restore the dry skin to normal.

Foot Diseases↗
PubMed1997

[Examination of a novel wax teat bougie for treatment of wounds in the papillary lactiferous sinus of dairy cows with special regard to endoscopic documentation of mucosal reactions compared with conventional teat bougies and a teat cannula].

The present study on a novel wax-teat bougie, developed by Dr. T. GEISHAUSER for treatment of wounds in the papillary lactiferous sinus of dairy cows, has been performed in two phases of investigation. In a first step, fourteen healthy dairy cows (Deutsch Schwarzbunt) in state of early lactation were dried off temporarily for five days, after checking milk samples of all quarters for six following-on days on their bacteriological status, number of somatic cells, conductivity and results of the California-Mastitis-Test (CMT). The drying off was performed on two Quarters with similar cell-count in milk samples each. In one teat of the selected pairs off udder quarters, the wax-bougie was applied (group I), the other corresponding udder quarters were used as a control (group II). After five days of drying off, lactation was started again after removing the bougies in treated quarters. For another five days milk samples out of the quarters in groups I and II were checked in the laboratory tests named above and mean values and increase differences of results were compared. Comparison of increase differences with t-test showed no statistically significant difference between drying off procedures with the wax-bougie and without any treatment in the parameters named above. Courses of counts of somatic cells, conductivity and CMT showed no significant differences between drying off probands by using the novel wax-bougie and drying off without further treatment. In the second phase of the study, fifteen lactating, healthy dairy cows as probands have been split in five groups. Three cows (twelve udder quarters) were dried off for five days by using the novel teat bougie (group D), in three groups (A,B,C) two different types of conventional teat bougies and one type of cannula were used, and, as a control three cows (group E) were dried off without any treatment. Before drying off the udder quarters and after starting lactation again, the condition of the mucosa in the teat papillary lactiferous sinus has been documented by means of endoscopy and the bacteriological status of milk samples has been determined. As a result all udder quarters dried off temporarily showed endoscopically detectable inflammatory-proliferating reactions in the mucosa of the papillary lactiferous sinus, whereas in cows treated with the novel wax-bougie (group D), as well as in the cows of the control group (E), there were no inflammatory reactions detectable at all. These different reactions, basing on the Fisher-test, have to be considered statistically significant (p < 0.001).

Animals↗