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Biomedical subjects

M Nicklasson

Publications and source records attributed to M Nicklasson.

14 recordsLinked to original sources
PubMed1986

Investigation of the film formation of magnesium stearate by applying a flow-through dissolution technique.

The film formation of magnesium stearate on the surface of acetylsalicylic acid was investigated by applying a flow-through dissolution technique. The effect of mixing time, lubricant surface area, and the addition of colloidal silica was studied. The film formation increased by increasing mixing time. The final level reached was independent of the specific surface area of the lubricants, but granular magnesium stearate gave a lower surface coverage than the powdered lubricants. The lubricating effect was independent of the mixing time and specific surface area of the lubricants. Colloidal silica was found to interact primarily with the free fraction of magnesium stearate.

Aspirin↗
PubMed1985

Preformulation studies in a drug development program for tablet formulations.

Recently developed techniques were applied in a preformulation program to select a compound and a suitable salt for use in a one-month toxicological test. The program showed that valuable information can be obtained prior to the choice of a compound as a candidate for a solid-dosage form. Information about the physical and mechanical properties of the chosen compound can be obtained with a limited amount of substance, i.e., surface color and hygroscopicity (1-2 g), dissolution rate and solubility (1-2 g), powder properties (1-2 g), and compaction properties (5-7 g).

Chemical Phenomena↗
PubMed1984

Linear systems analysis and moment analysis in the evaluation of bacampicillin bioavailability from microcapsule suspensions.

Linear systems analysis, i.e., numerical convolution/deconvolution, and moment analysis have been performed on data obtained from microcapsules containing the ampicillin prodrug bacampicillin hydrochloride. Three batches with different in vitro dissolution rates were scrutinized. From the results, it is concluded that numerical convolution/deconvolution is a valuable tool for predicting bacampicillin bioavailability. However, it must be emphasized that the selection of an appropriate time module is important for predicting an in vivo response that reflects the actual situation. This was verified by comparing the predicted plasma response values with the values obtained in a bioavailability study in healthy volunteers. A correlation between mean residence time in vivo and mean dissolution time in vitro was also found which thus demonstrates the usefulness of moment analysis for obtaining an in vivo-in vitro relationship. This relationship was compared to a correlation found between the mean dissolution time in vitro and the empirical maximum plasma concentration of bacampicillin.

Adult↗
PubMed1984

Correlations between in vitro dissolution rate and bioavailability of alaproclate tablets.

In two different absorption studies, quantitative correlations between the in vitro dissolution rate and the bioavailability have been shown after single administration of various tablet compositions of alaproclate hydrochloride to healthy subjects. Both statistical moment analysis and the use of empirical single value parameters were tested. For conventional tablets a linear relationship was obtained between mean dissolution time in vitro and in vivo. A similar relationship was obtained between the mean dissolution time in vitro and the mean residence time for controlled release tablets of the matrix type. It was also possible to establish an in vitro--in vivo correlation for these latter tablets by using the single point estimate of maximum plasma concentration as in vivo parameter. When comparing the mean dissolution time in vitro to the total area under the plasma drug concentration-time curve attained after different types of tablets, it is obvious that the extent of bioavailability of alaproclate will not fall below 80% of the value found for an aqueous solution until the mean dissolution time in vitro exceeds approximately 3 hr. Statistical moment analysis seems to have a broader applicability than the use of empirical point estimates, and it seems to be useful both for conventionally dissolving tablets and controlled release tablets.

Absorption↗
PubMedDate not supplied

Optimization of a fluid bed spray coating process using reduced factorial design.

A sequential approach to the optimization of a fluid bed coating process of pellets for controlled release using organic solvents and ethylcellulose has been applied using reduced factorial experiments. The optimization was started by applying a 2(4-1) experiment then, based on the results from that study, further experiments were carried out where only the variables which had the most significant effect on the film yield were used. Finally, a 2(3-1) experiment was performed. A relationship was found between the film yield and degree of agglomeration, indicating a limiting value of the film yield (75 per cent) below which only little agglomeration takes place. Above this value, the degree of agglomeration increases dramatically. The limit value was found to change only to a minor extent as a function of experimental conditions.

Delayed-Action Preparations↗
PubMedDate not supplied

Bioavailability of benzo(a)pyrene deposited in the lung. Correlation with dissolution from urban air particulates and covalently bound DNA adducts.

Dissolution kinetics of benzo(a)pyrene (B(a)P associated with urban air particulates were investigated in vitro and related to availability of the carcinogen in the isolated, perfused, and ventilated rat lung. Calculations of bioavailability and mean dissolution time in the lung produced results in concordance with experimental data. By convolution calculation, with in vitro desorption as input function and the disposition of B(a)P dosed intratracheally to the lung in an alveolar surfactant solution as reference, hypothetical areas under B(a)P buffer concentration vs. time curves (AUC) were calculated. AUC value for 1.5 micrograms of microcrystalline (MCr) B(a)P was 16 +/- 2 pmol/ml/min (N = 6), which was identical with the corresponding experimental value of 16 +/- 5 pmol/ml/min (N = 6), from lung perfusion experiments. For B(a)P adsorbed to urban air particulates (UAP-1), predicted and experimental AUC values did amount to 7 +/- 2 (N = 5) and 10 +/- 4 (N = 5) pmol/ml/min, respectively. Absolute bioavailability was calculated by deconvolution to 87% for B(a)P in alveolar surfactant. In vitro dissolution of B(a)P from urban air particulates (UAP-1 to -4) revealed a wide variation in desorption characteristics for different particulate samples. Dissolution parameters determined in vitro were positively related to mean absorption time and mean dissolution time in the lung, using three different preparations. The precision in predictions of availability of B(a)P from in vitro desorption rates, with MCr and UAP-1 representing the greatest differences observed, supports the hypothesis that desorption is the rate-limiting step during uptake of B(a)P in the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants, Occupational↗