Biomedical subjects

A J Vanderwielen

Publications and source records attributed to A J Vanderwielen.

7 recordsLinked to original sources

PubMed1984

Liquid chromatographic assay for diflorasone diacetate in cream and ointment formulations.

A high-performance liquid chromatographic assay for quantitating diflorasone diacetate (I) in cream and ointment formulations and in bulk form is described. Isoflupredone acetate (II) was used as the internal standard and a 3-micron silica gel column with a mobile phase comprised of water-saturated butyl chloride-water-saturated methylene chloride-tetrahydrofuran-acetic acid (350:125:10:15) led to an efficient separation. The method gave accurate results for four formulations, two creams and two ointments, as well as the bulk drug. The assay has an RSD of approximately 1.8% for the cream formulations, 1.3% for the ointment formulations, and 1.0% for the bulk drug. The method is specific for I and capable of resolving structurally related compounds.

Betamethasone↗

PubMed1981

Stability-indicating assay for hydrochlorothiazide.

A stability-indicating method for determining hydrochlorothiazide in tablet formulations and in the bulk form is described. Hydrochlorothiazide is dissolved or extracted using methanol. An aliquot of the solution, containing sulfadiazine as an internal standard, is chromatographed on a 10 micron C18 column with an aqueous mobile phase containing 5% methanol as the modifier. The pH is adjusted to about 4.5 with acetic acid. The method gave accurate results for nine lots (four different suppliers) of tablets and two bulk drug lots (two different suppliers). The assay has a relative standard deviation of about 1%. The method can also be used as a test for impurities in hydrochlorothiazide. The data in this study indicate that the test should give accurate results for impurities between 0.1 and 5%.

Chromatography, High Pressure Liquid↗

PubMed1980

Particle-size analysis of pharmaceutical powders.

An automated electrolytic sensing zone (electrozone) method was developed to determine the particle-size distribution of milled and micronized pharmaceutical powders. The powdered drugs obeyed log-normal statistics, and the distributions were well defined by thier geometric volume mean diameter and the geometric standard deviation. The results show that accurate data can be obtained between 2 and 80 micron with a precision of approximately 0.5 micron. Pulse-width analyses were performed to determine the feasibility of using a pulse-width discrimination program. However, in this case, the program discriminates against real particles and, therefore, its usefulness is limited. Milled and micronized materials are described adequately by a spherical diameter, and the automated electrozone system described is an excellent method for quality control purposes.

Chemistry, Pharmaceutical↗

PubMed1979

Molecular weight determination of commercial heparin sodium USP and its sterile solutions.

A liquid chromatographic assay for the characterization of heparin sodium USP, and heparin sterile solutions was developed. The method employs size exclusion chromatography and computer-based data collection and manipulation. An examination of commercially available heparin showed only minor differences between the heparins extracted from beef lung and porcine intestinal mucosa. The molecular weight averages of the material and its sterile solutions were 9000-12,000 daltons. A correlation was observed between average molecular weight and anticoagulant activity for the heparin sodium samples examined.

Animals↗

PubMed1978

Physical characterization of erythromycin: anhydrate, monohydrate, and dihydrate crystalline solids.

Hot-stage microscopy, thermoanalytical methods, and X-ray powder diffraction were used to demonstrate that crystalline erythromycin dihydrate converts to the crystalline anhydrate via a noncrystalline intermediate. X-ray powder diffraction, IR spectral, thermogravimetric, and differential thermal analyses were used to characterize the monohydrate material. The flow interrupt technique, a procedure recently developed to deal with low surface area samples, was employed successfully in obtaining isotherms and specific surface areas for the monohydrate and anhydrate. The relative dissolution rates of the various hydrates were determined in an aqueous solution (0.01 M phosphate buffer, pH 7.5) at 37 degrees. The results showed a significant difference in the dissolution rate of the dihydrate compared to the monohydrate and anhydrate.

Chemical Phenomena↗

PubMedDate not supplied

Application of total organic carbon analysis to cleaning validation.

Cleaning validation is the process of assuring that cleaning procedures effectively remove residue from manufacturing equipment/facilities below a predetermined level. This is necessary to assure the quality of future products using the equipment, to prevent cross-contamination and as a GMP requirement. Currently, cleaning validation samples are measured using HPLC or spectrophotometric methods of analysis which are often time consuming and subject to a number of interferences. Total Organic Carbon (TOC) analysis is a new method which has previously only been applied to measurement of carbon residues on production surfaces for biopharmaceuticals. We have applied the TOC analysis method to a number of traditional pharmaceutical products including antibiotics, steroids, and antinauseants in addition to biopharmaceuticals. The method offers extremely low detection capability (ppm and ppb), rapid sample analysis time and therefore quick turn-around of production equipment and facilities. TOC analysis is also applicable to on-line analysis. The method allows the measurement of extraneous materials such as process intermediates, cleaning agents, and protein materials not possible by other methods.

Carbon↗

PubMedDate not supplied

Total organic carbon method for aspirin cleaning validation.

Cleaning validation is the process of assuring that cleaning procedures effectively remove the residue from manufacturing equipment/facilities below a predetermined level. This is necessary to assure the quality of future products using the equipment, to prevent cross-contamination, and as a World Health Organization Good Manufacturing Practices requirement. We have applied the Total Organic Carbon (TOC) analysis method to a number of pharmaceutical products. In this article we discuss the TOC method that we developed for measuring residual aspirin on aluminum, stainless steel, painted carbon steel, and plexiglass. These are all surfaces that are commonly found as part of pharmaceutical production equipment. The method offers low detection capability (parts per million levels) and rapid sample analysis time. The recovery values ranged from 25% for aluminum to about 75% for plexiglass with a precision of 13% or less. The results for the plexiglass tended to vary with the age of the surface making the determination of an accurate recovery value difficult for this type of surface. We found that the TOC method is applicable for determining residual aspirin on pharmaceutical surfaces and will be useful for cleaning validation.

Aspirin↗