Biomedical subjects

H Van Doorne

Publications and source records attributed to H Van Doorne.

11 recordsLinked to original sources

PubMed1992

Activity of gentian violet and brilliant green against some microorganisms associated with skin infections.

The antimicrobial activity of gentian violet and brilliant green was tested against various strains of potential skin pathogens, by means of agar diffusion assay. The activity of both compounds was affected by pH. Gentian violet was found to be more active than brilliant green at pH 7.4, particularly against Pseudomonas aeruginosa. The spectrum of activity of gentian violet was not increased by the addition of brilliant green. An aqueous solution of gentian violet 0.5% turned out to be an adequate topical anti-infective drug. The preparation is particularly suitable for primary health care in tropical developing countries, because it is cheap, chemically and physically stable, and easy to prepare.

Anti-Infective Agents, Local↗

PubMed1988

Gamma irradiation of Sennae Folium. Microbiological and phytochemical studies.

The effect of different doses of gamma irradiation on senna leaves was studied. No changes in sennoside content and composition were observed after irradiation with 25 kGy. It was demonstrated that a minimum dose of 10 kGy was necessary to obtain a product of good microbiological quality. Cold maceration of senna leaves has to be discouraged, because of unavoidable microbial growth. Hot extraction is the method of choice for tea preparation. The rationale of gamma irradiation is discussed.

Cassia↗

PubMed1988

The suitability of some preservatives in chloroquine phosphate syrup.

In Third World countries chloroquine phosphate syrup is frequently prepared with chloroform as a preservative. Because of the toxic side effects of chloroform the suitability of a number of possible alternatives were investigated. If the chloroquine phosphate syrup is prepared as such, the combination of sorbic acid (1.5 g/l) and citric acid (2 g/l) is preferred. If, however, the chloroquine phosphate syrup is prepared from a stock solution of simple syrup, the relatively low pH may be undesirable, because it may negatively affect the stability or solubility of other medicinal compounds. For a stock solution of simple syrup the combination of methyl paraben (1.8 g/l) and propyl paraben (0.2 g/l) is preferred. Good care must be taken that a layer of condense water cannot be formed.

Administration, Oral↗

PubMed1988

Formation and antimicrobial activity of complexes of beta-cyclodextrin and some antimycotic imidazole derivatives.

Complex formation between beta-cyclodextrin and six antimycotic imidazole derivatives has been studied. The solubility of all drugs was increased in the presence of beta-cyclodextrin. The smallest increase (approx. 5-fold) was observed for miconazol, and the largest increase (approx. 160-fold) was observed for bifonazol. Apparent 1:1-complex constants were measured and found to decrease in the order: bifonazol greater than ketoconazol greater than tioconazol greater than miconazol greater than itraconazol greater than clotrimazol. The complexes appeared to possess a low, if any, antimicrobial activity. Measurement of inhibition zone sizes, with four test organisms was used to study the release of the antimycotic drugs from topical preparations. The antimycotic drugs were more readily released from topical preparations containing beta-cyclodextrin than from the same vehicles without beta-cyclodextrin. The rationale of beta-cyclodextrin addition to antimycotic topical preparations is discussed.

Anti-Infective Agents↗

PubMed1987

Native starch in tablet formulations: properties on compaction.

Maize, potato, rice and tapioca (cassava) starch were evaluated with respect to their properties on direct compression. Rice starch showed much better compactibility as compared to maize, potato and tapioca starch. Moreover, its binding capacity proved to be almost insensitive to mixing with magnesium stearate. This in contrast to the dramatic decrease in crushing strength of potato starch tablets containing the lubricant. The compactibility of the starches was found to be strongly affected by the equilibrium moisture content of the starches, which is dependent on the relative humidity of the atmosphere under which the powders were stored. All starches showed adequate capacity for water uptake to act as a disintegrant. Rice starch exhibited worst flowability, caused by its fine particle size as compared to the other starches. Granulation of rice starch changed it into a potential filler-binder in tablets prepared by direct compression.

Chemistry, Pharmaceutical↗

PubMed1985

Skin irritation caused by transdermal drug delivery systems during long-term (5 days) application.

We have studied the skin irritation produced by the prolonged application of transdermal therapeutic systems. The systems were applied to the skin of the back of male volunteers for 120 hours, and sweat accumulation and bacterial growth were studied. In some cases hydrogel discs were attached to the systems. The results showed that sweat accumulation contributed more to the skin irritation than the bacterial overgrowth. The incorporation of hydrogels in the transdermal delivery system may help to reduce skin irritation by absorbing water.

Administration, Topical↗

PubMed1984

Comparison of media and temperature of incubation for microbiological examination of purified water.

The suitability of four commonly used nutrient media, and two incubation temperatures for the bacteriological examination of purified water was investigated. The temperature of incubation (22 or 30 degrees C) exerted no profound influence on the observed numbers of colony forming units. Five days was optimal for all incubation conditions. Tryptone Soya Peptone Broth Agar was found to be less productive than the other media investigated, viz. Nutrient Agar 1/8 strength, Nutrient Agar and King A medium, which appeared to be equally productive.

Colony-Forming Units Assay↗

PubMed1984

A note on the suitability of 'dip slides' for the microbiological examination of water and aqueous non-sterile pharmaceutical preparations.

The suitability of four brands of dip slides for the examination of purified water was studied. Especially when used in combination with a calibrated inoculating device reliable results were obtained. The usefulness for this purpose of the selective media present on three of the four brands is questionable, unless a previous resuscitation technique has been applied.

Drug Contamination↗

PubMed1983

Synthesis, physical properties and microbiological activities of more water soluble silver sulfadiazine derivatives.

In this study the preparation of five hydrophilic derivatives of sulfadiazine is reported. The common structural element in the compounds is the 2-sulfonamidopyrimidine moiety. Three of these compounds are suitable for the preparation of a photostable I: I silver compound. These silver compounds are five to ten times more water soluble than silver sulfadiazine. The IR, 1H- and 13C-NMR data point to a similar co-ordination of silver in these compounds as with silver sulfadiazine. The microbiological activity of these silver compounds against St. aureus is slightly lower.

Bacteria↗

PubMed1982

Selective isolation and enumeration of low numbers of Staphylococcus aureus by a procedure that relies on elevated-temperature culturing.

A procedure for the selective detection of Staphylococcus aureus was elaborated, consisting of three parts: (i) enrichment in liquid Baird-Parker medium; (ii) isolation on Baird-Parker agar incubated at 43 degrees C, and (iii) confirmation by means of the test for thermostable nuclease. Elevated-temperature incubation of Baird-Parker medium did not make it inhibitory to cells stressed by heat treatment or osmotic shock.

Bacteriological Techniques↗

PubMedDate not supplied

Industrial manufacture of parenteral products in The Netherlands. A survey of eight years of media fills and sterility testing.

Sterility testing and media fills are essential requirements in the pharmaceutical industry. With the results obtained the manufacturer must ensure that the aseptic filling process is under control. In an eight year (1988-1995) retrospective survey of three major Dutch pharmaceutical companies the performance of the sterility test, of media fills and their relationship have been statistically evaluated. The products included human and veterinary pharmaceuticals and biologicals, and were divided into six different groups according to their production process and primary containers. A distinction was made between the results from the period 1985-1991 and the period 1992-1995, because this made the statistical analyses of a number of types of products possible, and because some significant changes in the production process were made in 1991 at some of the production sites. The results of the evaluation of the sterility test show that the frequency of false positives has not changed significantly. The overall rate of false positives of 0.17% is a factor ten better than considered acceptable by USP XXIII. For all product groups the frequency of positive sterility tests has decreased during the period of investigation. During the period 1992-1995 there was no significant difference between the results of product sterility tests and the negative controls for any of the product groups. This indicates that given the present state-of-the-art production the sterility test offers little or no additional security. The overall contamination of the media fills done in the more recent period is a factor twenty better than the limit given in the PDA Technical Monograph No. 2. In the more recent period there is a good agreement between the observed positive rate of the sterility tests and the positive rate that had been estimated from the results of the media fills. This indicates that despite some shortcomings, media fills are an adequate simulation of the production process and can be used to give an estimate of the rejection rate for the various product groups. The overall conclusion is that the production conditions of the participating Dutch pharmaceutical companies comply with the current international guidelines for aseptic production and sterility testing.

Drug Contamination↗