Biomedical subjects

M Juslin

Publications and source records attributed to M Juslin.

4 recordsLinked to original sources

PubMed1997

Frictional work in double-sided tablet compression.

The aim of this study was to evaluate the friction during double-sided tablet compression. Dicalcium phosphate dihydrate and lactose were tabletted with a compaction simulator with symmetrical and asymmetrical double-sided sawtooth punch displacement profiles. The estimation of force transmission in a powder column was based on an exponential equation, including the material parameter consisting of both the friction coefficient and Poisson's ratio. This parameter was predetermined from a single-sided compression. A novel equation was derived from a previously presented equation for friction work in single-sided tablet compression. The basic assumption was drawn from the linearly decreasing movement of infinitely thin particle layers, which are produced as the compressing punch surface approaches the other punch. This calculation was also based on the assumption that the equilibrium point, where the particles do not move, is halfway between the punches in the symmetrical profile and at a distance proportional to the amplitudes of the asymmetrical upper and lower sawtooth profiles. The tensile strength of tablets compressed with single-double-sided profiles was identical, and thus the behavior of the materials studied under compression was independent of the compression profiles. The friction work values that were calculated with the proposed expression for double-sided profiles were close to the theoretical values, as estimated by calculations based on compressions with single-sided profiles. In conclusion, the novel mathematical expression opens new possibilities for the evaluation of friction in double-sided compression; for example, in rotary press tabletting.

Friction↗

PubMed1984

Xylan--a possible filler and disintegrant for tablets.

Xylan, a novel possible adjuvant for tablets was tested and compared with modified starch, Sta-Rx 1500, for weight variation, strength and disintegration of tablets. There was no remarkable difference in weight variation between the tablets of the corresponding compositions. The tablets containing xylan were stronger and disintegrated more rapidly than those containing modified starch.

Adjuvants, Pharmaceutic↗

PubMed1983

Prolonged pulse-entry of pilocarpine with a soluble drug insert.

Apparent biophase availability of pilocarpine was studied in the eyes of albino rabbits. Pilocarpine doses of 0.85 and 2.30 mg in aqueous solutions, 1.00 mg in oil and 0.85 mg in a solid insert, were applied ocularly. The insert was a water soluble polyvinylpyrrolidone (PVP) matrix, which released 80% of its pilocarpine content in 35 min in vitro. In the inferior fornix of the eye this insert gelled in about 5 min and dissolved in 1 h. Pupillary diameters were measured and converted to values for the response parameter (RP). Time delay and magnitude of peak response, apparent biophasic availability (area under the curve of RP vs time), and a constant for the apparent rate of elimination were calculated from RP values. The time delay for the peak response was 16.l3-24.0 min, and the constant for apparent rate of elimination was 0.69-0.81 h-1. Neither time delay nor this constant was affected by the dose or the dosage form. Magnitude of the peak response and apparent biophasic availability were influenced by the vehicle and the dose: insert (0.85 mg) greater than oily solution (1.00 mg) greater than aqueous solution (2.30 mg) greater than aqueous solution (0.85 mg). The insert and oily solution did not show vehicle-controlled drug absorption and can be regarded as prolonged pulse-entry medication.

Animals↗

PubMed1983

Compressional characteristics of four starches.

Compression data about barley, corn, potato and wheat starches were obtained by two methods: the ejected tablet method and the tablet-in-die-method. These data were analysed using the Heckel and the Cooper-Eaton equations. The Heckel equation appeared to be the more sensitive in distinguishing the various stages during the compression. Die filling and rearrangement processes for the starches were especially dependent on particle size and shape and thus on contact area between particles. Densification of large starch particles (potato starch) owed more to die filling and less to rearrangement. Densification of small particles (corn starch) was the reverse. Starch having a wide particle size distribution (wheat) or an irregular particle shape (barley) underwent a relatively small amount of densification as a result of die filling and a relatively great amount of densification because of rearrangement of particles during tableting. The tendency of the starches to total and pure plastic deformation was dependent on particle size, size distribution and particle shape. Corn starch was the most prone to plastic flow with only little elastic recovery. Potato starch also flowed plastically with ease. Barley and wheat starches were the more elastic.

Drug Compounding↗