Rosin Ester Research Articles

Evaluation of Propylene Glycol Rosin Ester as Microencapsulating Material and Study of Dissolution Kinetics

AbstractPropylene glycol rosin ester (PgR Ester) was prepared by heating rosin with propylene glycol at 220°C. The physicochemical properties were studied. Aspirin granules were encapsulated using a standardized coating technique. The microcapsules were evaluated for moisture absorption, flow properties and friability studies. The dissolution studies were carried out in five different pH media to know the effect of pH on release characteristics. The dissolution studies revealed that PgR Ester films impart varying degrees of resistance to different pH media. The t50% values were found to be 57,47,63,93 and 88 min in pH 1.2,3.0,5.0,7.2 and 8.0 media, exhibiting potential usefulness of PgR Ester as film coating material. The release patterns obey Hixson Crowell cube root dissolution law, the values of cube root constant are given.

Determination of Rosin Ester Gum Emulsifiers in Fruit Juices by Gas Chromatography

A method for detection and determination of rosin ester gum in fruit juice was established as follows. Rosin ester as a component of ester gum was extracted with benzene from the sample, and saponified with N/2 KOH-ethanol solution. The rosin acids were extracted with diethyl ether in acidic condition, derivatized with TMS reagent and determined by gas chromatography (GC). Seven kinds of ester gum standard were analyzed by the proposed method, and it was found that contents of dihydroabietic acid and abietic acid in the ester gums ranged between 33.8–75.1% and 0–36.7%, respectively, but the total contents of them were 66.7–75.1% (average, 70.9 ± 3.0%). Dihydroabietic acid and abietic acid derived from ester gum in 6 kinds of imported fruit juice were identified by GC-mass spectra and quantitated by GC. The contents of ester gum in samples estimated from the two peaks were 15.2–33.9 ppm. Recoveries of ester gum added to sample at 50 and 500 ppm were more than 92.7%, and the detection limit of ester gum was 0.5 μg (2 ppm in sample) by the proposed method.

Study of rosin and rosin derivatives as coating materials for controlled release of drug

Rosin and rosin derivatives are widely used as film-forming agents in paints and varnishes. Their use as coating materials has been reported. This paper describes the evaluation of rosin derivatives such as rosin pentaerythritol ester, rosin maleic acid adduct esterified with glycerol and pentaerythritol, and abietic acid as coating materials. Salicylic acid granules were coated and evaluated for moisture absorption, flow characteristics and in vitro dissolution studies. It is observed that rosin and pentaerythritol ester impart excellent moisture protection and these can be used for enteric coating and controlled release of drug.

In vivo performance of pentaestergum-coated aspirin microcapsules.

The in vivo study of the pentaestergum-coated aspirin microcapsules was carried out in two healthy female dogs. Blood samples were collected at different time intervals and analysed for total salicylate content. The results were compared with plain aspirin granules. A delayed release of drug was observed from pentaestergumcoated drug microcapsules. Various pharmacokinetic parameters have been calculated and reported. The drug is absorbed from the dosage form and is made available for further therapeutic action at a particular receptor site. This is known as the bioavailability of the drug. The extent of drug absorbed and the rate of absorption are affected by a number of factors dependent upon the physicochemical properties of the drug, its biological properties and patient’s factors. The extent of drug absorption also depends upon the variable nature of the chemical environment throughout the length of the gastrointestinal tract. The extent of bioavailability is usually determined either by measuring the area under the blood concentration-time curve or from cumulative amounts of drug excreted in the urine. These are three parameters describing a blood level curve that are considered to be important in evaluating the bioequivalence of two formulations. These are (1) the peak height concentration, (2) the time of peak concentration and (3) the area under the plasma concentration-time curve. Although many in vitro methods are available and useful, there is no totally satisfactory in vitro substitute for the in viwo determination of drug availability in the evaluation of various dosage forms. We have reported the effect of pH on release characteristics of pentaestergum microcapsules (Pentaerythritol rosin ester) and the dissolution kinetics (Pathak and Dorle 1986). This communication deals with the in vivo evaluation of pentaestergum aspirin microcapsules in bitches. The drug was fed orally to the experimental animals. Blood samples were withdrawn at specified time intervals and analysed for total salicylates in the plasma. On the basis of plasma drug concentration various pharmacokinetic parameters have been studied and are discussed. Pentaestergum aspirin microcapsules were prepared by encapsulating aspirin I .I’. granules using a standard coating technique (Pathak et al. 1985). To study the in vivo performance two healthy bitches (A, 15 kg and B, 16kg) were used as experimental animals. They were fasted for 12 h before drug administration. Pentaestergum aspirin microcapsules were suspended in 20 ml of 5 per cent acacia solution, and 20 mg/kg aspirin dose equivalent microcapsules were administered through a stomach tube. An additional 50 ml of purified water was also given at the

Effect of pH on the release characteristics of pentaestergum microcapsules and a study of dissolution kinetics.

Rosin and rosin esters have excellent film-forming properties. Pentaerythritol-rosin ester (penta-ester gum) is found to be useful as moisture-protecting material with delayed release of drug. This communication relates the effect of pH on the release characteristics of a drug from penta-ester gum coated microcapsules. Salicylic acid granules were encapsulated using a 10 per cent solution of penta-ester gum in acetone. The microcapsules were evaluated for their drug release characteristics. Various pH media (pH 1.2, 3.0, 5.0, 7.2 and 8.0) were used. The results showed that penta-ester gum exhibits excellent resistance to higher pH levels and can be used for the sustained release of the drug. Dissolution rate constants were calculated and they agree with the assumption of Hixson and Crowell's cube-root equation.

Study of Rosin and Rosin esters as coating materials

Rosin esters were prepared by heating glycerol, sorbitol and mannitol. Aspirin granules were coated with solution of Rosin and Rosin esters in acetone. The coated granules were studied for moisture absorption, dissolution studies, and ageing studies. The results showed that rosin-coated granules release less than 10% drug in gastric media in 3 h and more than 75% drug in 15 min in intestinal media. Rosin can be used as enteric coating material. Rosin esters give quick release in gastric media and delayed release in intestinal media. Ageing does not have a significant effect in release characteristics. Rosin and Rosin esters are widely used as film-forming plasticizers for moisture protection and find use in chlorinated rubber, vinyl resins, paints and varnishes. Glycerol ester of Rosin has been used as an anhydrous binding agent in tablet formulation (Surowiecki et al., 1971). A formula is patented for repeat action beadlets using abietic acid-type Rosin and Zein (Butler and Vance, 1968). This communication explains the application of Rosin and Rosin esters as coating materials. It was found that Rosin can be used for moisture protection and enteric coating purpose while Rosin esters can be used for controlled release. Rosin esters of glycerol (Kogan, 1932) mannitol and sorbitol (Brown and Geopp, 1938) were prepared by heating Rosin (4 parts) and glycerol (1 part) at 210-220°C. Heating was continued until there was no further drop in acid value of the sample withdrawn from the reaction. The whole mass was poured in water, to remove excess of alcoholic compound, with constant stirring, filtered and dried at 50°C in the oven overnight.

The viscoelastic properties of rubber–resin blends. III. The effect of resin concentration

AbstractThe viscoelastic properties of a rubber–resin blend, which influences performance of the blend as a pressure‐sensitive adhesive, depend upon the structure of the resin as well as its molecular weight. The effect of the concentration of a compatible resin in the blend was examined using a mechanical spectrometer. Four types of resins were used. These are the rosin esters, polyterpenes, pure monomer resins such as polystyrene and poly(vinyl cyclohexane), and petroleum stream resins. Each was examined in blends with both natural rubber and styrene–butadiene rubber over a range of concentrations. It is shown that the temperature of the tan δ peak for compatible systems can be predicted by the Fox equation, T = W1T + W2T, where W1 and W2 are the weight fractions of the resin and rubber, respectively, and the Tg's are the tan δ peak temperatures in K. The plateau modulus G for a blend can be identified as the G′ value in the rubbery plateau at the point where tan δ is at a minimum. The relationship between G and G, the plateau modulus for the undiluted elastomer, is shown to be proportional to the volume fraction of the elastomer raised to the 2.3–2.4 power for natural rubber with six different compatible resins. The exponent for styrene–butadiene rubber is 2.5–2.6 with four different resins. Using these relationships, both the tan δ peak temperature and plateau modulus can be predicted for a rubber–resin system from data on the unmodified elastomer and on one typical rubber–resin blend.

Study of rosin glycerol esters as microencapsulating materials.

Rosin esters were prepared by heating rosin with glycerol and intermediate reaction products with different acid values were withdrawn. Salicylic acid granules were encapsulated using a 10 per cent solution of rosin esters in acetone. The coated microcapsules were evaluated for moisture absorption, flow properties and dissolution studies. The results showed that rosin and rosin-glycerol intermediates with acid values of 122, 105 and 55 had excellent moisture protection properties. Dissolution studies showed that these could be used for delayed release of drug.

Peel adhesion and viscoelasticity of rubber–resin blends

AbstractMixtures in various proportions of natural rubber (NR) and each of two tackifier resins, a poly‐β‐pinene and a modified pentaerythritol rosin ester, were used as the adhesive layer in joining a flexible polyester strip to a plane glass substrate. Measurements of the force required to peel the strip from the glass at a 90° angle were made over a range of pulling rates at several temperatures. Application of time‐temperature superposition enabled a master curve of (reduced) peel force versus (log) pulling rate at a standard temperature (296 K) to be obtained for each adhesive composition. The master curves showed, in increasing order of pulling rate, some or all of four different modes of peeling: (i) peeling with viscous adhesive response, (ii) peeling with rubbery response, (iii) oscillatory or slip‐stick peeling, and (iv) peeling with glassy adhesive response. In general, transitions between the different peeling modes were quite abrupt. Increase in concentration of tackifier resin caused displacement of the master curve toward lower pulling rates [an effect interpreted in terms of an increasing adhesive glass temperature (Tg)], and a superimposed displacement of the transition between peeling modes (i) and (ii) toward higher pulling rates‐an effect attributed to reduction in adhesive average molecular weight. The influence of the tackifier resin in modifying the viscoelastic characteristics of the adhesive was further demonstrated in a comparison of the peel force master curves with corresponding master curves of dynamic storage modulus.

Studies on the Utilization of Tall Oil II.

In the previous paper, preparation of the mixed methyl esters, consisted of fatty and rosin esters, was discussed. In this paper, these esters were converted into mixed alcohols, consisted of fatty and rosin alcohol, by Bouvealt-Blanc reaction. The kind, amount of reduced alcohol, amount of sodium in the reduction and the distillation of produced crude alcohol were discussed. Tertiary butyl alcohol was most suitable for reduction in the case of all esters. Because saponification value of the esters containing rosin ester can not be accurately determined, theoretical requirement for sodium and reducing alcohol could not be calculated. However, excess sodium and reducing alcohol seems to increase the yield of mixed alcohol. Against author's expectation, these esters have a saponifying tendencies, when excess sodium is present. Methyl ester from distilled tall oil is less saponifiable than that from crude tall oil in the reduction reaction. When distilled the crude alcohols produced, under reduced pressure, fatty alcohols are distilled out firstly and the rosin alcohol subsequently. Distillation residue is considered to be a polymerized rosin esters, the rotation property of which is extremely changed owing to the isomerization caused by heating.