PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Lubricants”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2001

Comparative evaluation of tableting compression behaviors by methods of internal and external lubricant addition: inhibition of enzymatic activity of trypsin preparation by using external lubricant addition during the tableting compression process.

This study evaluated tableting compression by using internal and external lubricant addition. The effect of lubricant addition on the enzymatic activity of trypsin, which was used as a model drug during the tableting compression process, was also investigated. The powder mixture (2% crystalline trypsin, 58% crystalline lactose, and 40% microcrystalline cellulose) was kneaded with 5% hydroxypropyl cellulose aqueous solution and then granulated using an extruding granulator equipped with a 0.5-mm mesh screen at 20 rpm. After drying, the sample granules were passed through a 10-mesh screen (1680 microm). A 200-mg sample was compressed by using 8-mm punches and dies at 49, 98, 196, or 388 MPa (Mega Pascal) at a speed of 25 mm/min. The external lubricant compression was performed using granules without lubricant in the punches and dies. The granules were already dry coated by the lubricant. In contrast, the internal lubricant compression was performed using sample granules (without dry coating) containing 0.5% lubricant. At 98 MPa, for example, the compression level using the external lubricant addition method was about 13% higher than that for internal addition. The significantly higher compressing energy was also observed at other MPas. By comparison, the friction energy for the external addition method calculated based on upper and lower compression forces was only slightly larger. The hardness of tablets prepared using the internal addition method was 34% to 48% lower than that for the external addition method. The total pore volume of the tablet prepared using the external addition method was significantly higher. The maximum ejection pressure using the no-addition method (ie, the tablet was prepared using neither dry-coated granules nor added lubricant) was significantly higher than that of other addition methods. The order was as follows: no addition, external addition, and then internal addition. The ejection energy (EE) for internal addition was the lowest; for no addition, EE was the highest. In the dissolution test, the tablets obtained using external addition immediately disintegrated and showed faster drug release than those prepared using internal addition. This result occurred because the water penetration rate of the tablet using the external addition was much higher. The trypsin activity in tablets prepared using the external addition method was significantly higher than that produced using the internal addition method at the same pressure. All these results suggest that the external addition method might produce a fast-dissolution tablet. Because the drug will be compressed using low pressure only, an unstable bulk drug may be tableted without losing potency.

Algorithms↗
PubMed2002

Patient preferences in a preliminary study comparing an intra-oral lubricating device with the usual dry mouth lubricating methods.

OBJECTIVE: To compare an intra-oral device to relieve oral dryness with the other methods of lubricating the mouth at night. DESIGN: Multidisciplinary single blind randomised cross over study. SETTING: The subjects were drawn from patients attending a dry mouth clinic. MATERIALS AND METHODS: Thirty-four dentate subjects attended on five occasions at intervals of 4 weeks. At the first visit the teeth were scaled and impressions were recorded. The device was fitted either on the second or the fourth visit. At all visits samples were taken of the resting and stimulated saliva for volumetric analysis and the dry mouth score recorded. Data were collected from the lubrication timings and the questionnaire. RESULTS: Ten water, nine saliva substitute and ten sugar-free chewing gum lubricators completed the study. There were 27 female and two male subjects with an average age of 62 years. Nine out of 10 of those lubricating with chewing gum preferred wearing the device (P = 0.037). After the device wearing period the subjects' self assessment of mouth dryness (P = 0.056), speech (P = 0.009) and swallowing (P = 0.031) were more favourable when compared with the alternative lubrication with 66% preferring the intra-oral device to their alternative method of lubrication. CONCLUSIONS: The majority of the subjects preferred wearing the device at night compared with their normal method of lubrication. Subjects' perception of dryness, speech and swallowing became closer to the clinician's assessment after wearing the device.

Adult↗
PubMed1985

A microbiological comparison of a povidone-iodine lubricating gel and a control as catheter lubricants.

A randomized, controlled study tested the value of a povidone-iodine (PVP-I) lubricant ('Betadine' lubricating gel), in preventing microbial contamination of bladder urine during catheterization. Urine samples, for culture, were obtained by suprapubic aspiration both before passage, and after removal 15 min later, of a no. 16 Foley catheter coated with the test lubricant or with a control preparation ('K-Y' lubricating jelly). Each treatment group included 10 men and five women. Swab cultures of the anterior urethra, taken immediately before catheterization, demonstrated substantial urethral contamination. Thirteen test subjects and 15 controls qualified for the efficacy analysis and all 30 took part in the safety evaluation. Before catheterization, mean colony counts per 5 ml urine numbered 0.3 in the (PVP-I) treated group and 0.4 among controls. After catheter passage, the mean counts were respectively, 3.6 and 69.6 per 5 ml. Thus, catheters coated with PVP-I lubricating gel transported significantly fewer (P less than 0.03) viable contaminants to bladder urine than those covered with 'K-Y' jelly. The organisms most frequently identified in urethral swabs and pre-study midstream clean-catch specimens also predominated in post-catheterization urine, but their incidence was considerably lower among the PVP-I treated subjects than among controls. Lubricity, cohesiveness and adhesiveness were more satisfactory in the test group than in the control series. No adverse reactions occurred and both preparations, as well as the mechanical procedures, were well tolerated. The findings demonstrated the efficacy of the PVP-I lubricant in preventing transfer of viable urethral organisms to the bladder during catheterization.

Adult↗
PubMed1998

A randomized controlled trial comparing nonoxynol-9 lubricated condoms with silicone lubricated condoms for prophylaxis.

OBJECTIVE: We tested the effect of nonoxynol-9 (N-9) in condom lubrication on the risk of acquiring STD and genital discomfort. METHODS: The study was a triple masked, randomised controlled trial comparing N-9 lubricated condoms with plain silicone lubricated condoms among Dominican female sex workers. RESULTS: Randomisation provided two groups (313 for N-9 and 322 for plain) similar in baseline characteristics, but extensive loss to follow up occurred (56 women in each group completed the 24 week follow up). Most vaginal acts with clients were protected with condoms (99% of vaginal sex) but fewer acts with non-clients were protected (43% of vaginal sex). No significant differences occurred in rates of cervical infections (N-9 = 3.4 per 100 person months v plain = 2.8), trichomoniasis (N-9 = 2.8 v plain = 3.6), or discomfort rates (N-9 = 0.82 v plain = 0.92). CONCLUSIONS: Plain silicone lubricated condoms are as effective as N-9 lubricated condoms, cost less, have longer expected shelf life, and therefore may be the better condom to provide.

Adolescent↗
PubMed1992

Characterization of a bovine synovial fluid lubricating factor. I. Chemical, surface activity and lubricating properties.

A lubricating glycoprotein (PSLF) with an apparent molecular weight of 280 kDa was purified from bovine synovial fluid by anion exchange, molecular sieve chromatography, and density gradient centrifugation. Lubrication was measured under boundary conditions as lowering of the coefficient of friction (mu) between oscillating natural latex and polished glass. Lubricating ability was first observed at a concentration of 200 micrograms/ml and became maximal at 260 micrograms/ml. Hydrophobic interfacial tension measurements indicated that at the former concentration, monolayers of PSLF formed. Sugar digestions showed that lubricating ability depends upon the terminal galactose of the molecule. PSLF is similar if not identical to lubricin. It is proposed that a repulsive hydration force is the molecular mechanism for lubricating activity.

Amino Acids↗
PubMed2005

Press chamber coating as external lubrication for high speed rotary presses: lubricant spray rate optimization.

Lubrication of the tooling (punches and dies) is necessary to produce tablets. The most commonly used lubricant is magnesium stearate. Adding and blending magnesium stearate to the tablet mass often has negative effects on the properties of the compressed tablets (e.g., decreasing the tensile strength of the tablet). To avoid these negative effects, external lubrication systems were developed. This study investigated the functionality and the influence of a new press chamber coating system called the PKB II. The major difference between the PKB II and previous systems is its ability to spray a mixture of powdered magnesium stearate and air directly onto the punches and dies which was determined to allow the running of the rotor at higher speeds. The data showed a clear correlation between the spray rate of the lubricant and the concentration of the magnesium stearate per tablet. The PKB II was designed to allow for adjustments, in order to optimize the spray rate, by using the ejection force. The concentration of magnesium stearate was reduced to approximately 0.04% per tablet, using the PKB II. Additionally, the most common negative effects, such as the decrease in tablet tensile strength, were avoided by using this system.

Calibration↗
PubMed1983

Boundary lubricating property of synovial fluid on artificial material and lubrication of artificial joints.

Boundary lubricating property of the synovial fluid on artificial materials was investigated by using a pendulum-type friction tester. The coefficient of friction between metal and metal with synovial fluid as a lubricant ranged from 0.19 to 0.30. Those between metal and plastic in the same condition ranged from 0.26 to 0.43. It is concluded from the above data that synovial fluid is a poor lubricant for artificial materials. The coefficient of friction of a metal on plastic prosthesis was approximately five times better than that of a metal on metal prosthesis in the pendulum experiments using synovial fluid as a lubricant.

Adult↗
PubMed1977

Mechanism of surface lubrication: influence of duration of lubricant-excipient mixing on processing characteristics of powders and properties of compressed tablets.

A mathematical expression for tablet hardness was related to lubricant mixing by considering increases in the surface coverage with prolonged mixing time. The duration of lubricant mixing significantly changed the apparent bulk volume of the mix, ejection force during tableting, hardness, and disintegration and dissolution properties of tablets. These findings may provide some rationale for the changes in processing characteristics and properties of finished drug products often encountered in the scale-up of solid dosage formulations. Several lubrication mechanisms are discussed in connection with the duration of mixing effects and scanning microscopy studies.

Drug Compounding↗
PubMed2003

Comparative study of the lubricant performance of Compritol HD5 ATO and Compritol 888 ATO: effect of polyethylene glycol behenate on lubricant capacity.

The aim of this paper is to study the lubricant capacity of Compritol HD5 ATO, a glyceryl and polyethylene glycol dibehenate, obtained by atomization. This material is compared to Compritol 888 ATO, constituted only by glyceryl dibehenate. First, this study verifies that Compritol HD5 ATO and Compritol 888 ATO present the same granular characteristics and that their mixes with Lactopress present no structural differences. Secondly, in term of compressibility and cohesiveness, the use of Compritol 888 ATO or Compritol HD5 ATO with Lactopress does not involve any significant modification. Finally, the minor difference of lubricant capacity between Compritol HD5 ATO and Compritol 888 ATO has no consequence in compression practice. The presence of polyethylene glycol behenate does not decrease the glyceryl dibehenate compression functionality. This study concludes that Compritol HD5 ATO could be a very interesting excipient because it associates the glyceryl dibehenate lubricant capacity with the polyethylene glycol behenate-specific capacity in terms of dissolution enhancement.

Chemistry, Pharmaceutical↗
PubMed1985

Masticatory lubrication. The role of carbohydrate in the lubricating property of a salivary glycoprotein-albumin complex.

We report for the first time a masticatory-lubrication assay system to assess the lubricating properties of salivary constituents. The lubricating ability of the proline-rich glycoprotein (PRG) of parotid saliva was enhanced by human serum albumin. The interactive effect of albumin was abolished by chemically deglycosylating the glycoprotein. Fluorescence spectroscopy with a hydrophobic probe verified the existence of a PRG-albumin complex and demonstrated that deglycosylation of the PRG altered the nature of its interaction with albumin.

Adult↗
PubMed1981

The molecular structure of lubricating glycoprotein-I, the boundary lubricant for articular cartilage.

Lubricating glycoprotein-I (LGP-I) was prepared from bovine synovial fluid by density gradient sedimentation and gel-permeation chromatography. The LGP-I sample obtained was able to lubricate articular cartilage in a manner equivalent to that of whole synovial fluid. Chemical, physical, and electron microscope measurements were carried out to determine the structure of the LGP-I molecules. The molecular weight calculated from sedimentation equilibrium measurements was 2 X 10(5), and the solute distribution obtained indicated that LGP-I was relatively monodisperse. The s(0)20,w value was 4.84, and the intrinsic viscosity was 92 ml/g. The molecular weight and diffusion coefficient calculated from later light-scattering measurements was 2.06 x 10(5) and 1.10 x 10(-7) cm2/s, respectively. The electron microscope measurements showed that the LGP-I molecules had a number average length of 204 nm, a weight average length of 222 nm (with a standard deviation of 54 nm), and a width of 1-2 nm. These data and the kinked appearance of the molecules indicate that LGP-I is a partially extended flexible rod. The hydrodynamic measurements also indicate that LGP-I has the same structure in solution, although the apparently high s(0)20,w value, compared to other rod-like molecules, suggests that due to its flexibility LGP-I can occupy a more compact domain than would be expected based on its extended dimensions. The name of "lubricin" is suggested for this lubricating glycoprotein.

Amino Acids↗
PubMed1993

The role of synovial fluid filtration by cartilage in lubrication of synovial joints--II. Squeeze-film lubrication: homogeneous filtration.

A mathematical model of synovial film filtration and synovial gel formation at normal approach of cartilage surfaces in the human hip joint is presented. The biphasic mixture model presented in Part I of this paper [Hlavácek, J. Biomechanics 26, (1993)] for synovial fluid and that of Mow and his collaborators [J. Biomech. Engng 102, 73-84 (1980)] for cartilage are used. A general analysis of filtration of an axially symmetric synovial squeeze-film between two cartilage layers at normal approach is given. The geometrically simple case much idealising the human hip joint is also considered: two cartilage discs with a synovial film in between are compressed by the steady loading of the half human weight. The homogeneous film filtration process where the synovial gap remains parallel and the macromolecular concentration in the gap is spatial homogeneous (to the thin-film approximation) and time-dependent is numerically analysed. If the hyaluronic acid concentration of the synovial gel at equilibrium is 50 mg/ml at least, the resulting stable gel layer thickness for the homogeneous filtration in the human hip joint and for normal synovial fluids is about 0.1 micron, being almost independent of the loading. Inflammatory synovial fluid shows values several times lower.

Adhesiveness↗
PubMed1995

The role of synovial fluid filtration by cartilage in lubrication of synovial joints--IV. Squeeze-film lubrication: the central film thickness for normal and inflammatory synovial fluids for axial symmetry under high loading conditions.

The axially symmetric problem of synovial film filtration and synovial gel formation at normal approach of cartilage surfaces in the human hip joint loaded by a compressive force has been solved numerically in Part III of this paper [Hlavácek and Novák, J. Biomechanics 28, 1193-1198 (1995)] for the Newtonian viscous phase of the biphasic synovial fluid and for low loads only. Because of a high non-linearity of the problem the method used there breaks down for higher loads. On anticipating that for a high step loading the fluid pressure in the central part of the squeezed synovial film is close to the pressure in a dry frictionless contact, the synovial film filtration at the film centre is governed by two ordinary differential equations that are easy to solve. The central gel film thickness thus obtained, i.e. the film thickness at the moment, when the filtered fluid turns into a stable gel is about 1 micron for the normal synovial fluid (with a non-Newtonian viscous phase of the synovial fluid) and changes very little if the geometric, material and loading parameters of the problem vary within the physiological range. The inflammatory case (with a more or less Newtonian viscous phase) yields values by one order lower at least. The results of stress analysis in the cartilage for this mixture model suggest the reason for vertical cracking at the free cartilage surface and horizontal splitting at the tide mark observed in osteoarthritic joints.

Biomechanical Phenomena↗