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Biomedical subjects

E Swanepoel

Publications and source records attributed to E Swanepoel.

8 recordsLinked to original sources
PubMed2003

Developing a discriminating dissolution test for three mebendazole polymorphs based on solubility differences.

Mebendazole, a broad spectrum anthelmintic drug, is practically insoluble in water and exists in three polymorphic forms, A, B, and C, of which C is pharmaceutically favoured. Since the dissolution of drugs from solid oral dosage forms can depend on the crystal form of the drug an attempt should be made while developing dissolution tests to set test parameters that are sensitive to changes in the crystal form. USP 24 describes 0.1 M hydrochloric acid containing 1.0% sodium lauryl sulphate (SLS) as the dissolution medium for mebendazole tablets. Results showed that the high concentration of sodium lauryl sulphate in the USP dissolution medium does not allow the use of this test to distinguish between the solubility differences of the three mebendazole polymorphs. By decreasing the amount of sodium lauryl sulphate in the dissolution medium clear differences in the dissolution rates of the three forms were observed. The most discriminating medium was 0.1 M HCl, containing no sodium lauryl sulphate.

Algorithms↗
PubMed2000

Dissolution properties of piroxicam powders and capsules as a function of particle size and the agglomeration of powders.

The poor dissolution characteristics of relatively insoluble drugs have long been a problem to the pharmaceutical industry. An example is piroxicam, a highly potent anti-inflammatory agent. In many countries, a large number of generic piroxicam products are available to the prescriber. The aim of this study was to investigate the cause of the dissolution problems experienced by manufacturers of generic piroxicam capsules. Two raw material batches and the dissolution properties of several piroxicam capsules were studied. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) results showed that the two raw material samples were identical with respect to polymorphic modification. The particles of powder 1 were smaller than those of powder 2, but the dissolution of powder 1 was much slower than that of powder 2. The dissolution results for the capsules showed a marked difference among different brands, with capsule C not meeting the USP tolerance. Adding surfactant to the dissolution medium increased the dissolution of both powder 1 and capsule C. Failure of powder 1 or capsule C to meet USP dissolution criteria could result in differences in product efficacy, as well as in potential side effects. Such observations should be taken into account along with other relevant considerations when decisions regarding the generic substitution of oral piroxicam products are made.

Administration, Oral↗
PubMed1999

The effect of polymorphism on powder compaction and dissolution properties of chemically equivalent oxytetracycline hydrochloride powders.

In South Africa, oxytetracycline is identified as an essential drug; many generic products are on the market, and many more are being developed. In this study, six oxytetracycline hydrochloride powders were obtained randomly from manufacturers, and suppliers were compared. It was found that compliance to a pharmacopoeial monograph was insufficient to ensure the optimum dissolution performance of a simple tablet formulation. Comparative physicochemical raw material analysis showed no major differences with regard to differential scanning calorimetry (DSC), infrared (IR) spectroscopy, powder dissolution, and particle size. However, the samples could be divided into two distinct types with respect to X-ray powder diffraction (XRD) and thus polymorphism. The two polymorphic forms had different dissolution properties in water or 0.1 N hydrochloride acid. This difference became substantial when the dissolution from tablets was compared. The powders containing form A were less soluble than that containing form B.

Calorimetry, Differential Scanning↗
PubMed1997

Malignant pericardial effusion in breast cancer: terminal event or treatable complication?

BACKGROUND: Few data are available on malignant pericardial effusion (MPCE) in breast cancer. We identify the patient prone to develop MPCE describe the result of surgical management, and try to identify a subgroup of patients who do not benefit from surgical management. METHOD: We performed an audit of our policy of active search for MPCE in breast cancer patients and its treatment by subxiphoid pericardial fenestration. RESULT: Nineteen patients with MPCE had a mean of 3.2 other sites of recurrence: 17 had pleural recurrence. Six patients had exertional dyspnea and 13 had dyspnea at rest; three needed emergency pericardiocentesis. An average of 740 ml of fluid was recovered; cytology was diagnostic in 11 cases and histopathology in 10 cases. At discharge, six patients had no dyspnea and six had exertional dyspnea. Of 10 patients who did not receive systemic treatment, eight died within 30 days. Nine patients who received systemic treatment had an average survival of 8.3 months. CONCLUSIONS: Patients with pleural recurrence presenting with dyspnea should be evaluated for the presence of a MPCE. Subxiphoid pericardial fenestration is the treatment of choice. Patients who will not receive systemic treatment should be managed conservatively.

Adult↗
PubMed1996

Fluorimetric method of analysis for D-norpseudoephedrine hydrochloride, glycine and L-glutamic acid by reversed-phase high-performance liquid chromatography.

The determination of D-norpseudoephedrine HCl, an appetite suppressant, and glycine and L-glutamic acid, both dietary supplements, in pharmaceutical formulations and dissolution media using reversed-phase high-performance liquid chromatography (HPLC) combined with fluorimetric detection is reported. A reagent solution containing omicron-phthalaldehyde and a reducing agent, mercaptoethanol, appeared to be the most favourable reagent for derivatising the three compounds. The use of this HPLC method allowed for selective and quantitatively accurate analysis and was sufficiently specific, precise and sensitive for analytical characterisation.

Appetite Depressants↗
PubMed1977

Increased concentrations of serum free fatty acids falsely increase serum thyroxine as determined by competitive protein-binding.

Markedly increased concentrations of free fatty acids after a fatty meal and heparin injection already have been shown to falsely increase thyroxine values measured by competitive protein-binding techniques, where ethanol extraction in used. We report here the effect of lesser increases. In 10 patients receiving heparin during hemodialysis we found significant increases in serum thyroxine by competitive protein-binding (mean, 20 nmol/l) and in free fatty acid concentrations (164 micronmol/l). Thyroxine measured as iodine did not change significantly. In seven subjects who had fasted for 27 h, we also noted significant increases in thyroxine by competitive protein-binding (mean 63 nmol/l) and in free fatty acid concentrations (624 micronmol/l). In a single subjects, serial measurements showed a close association of the two variables and the overall correlation between the increases was good. This artefact limits the value of many currently used thyroxine methods because it imposes restrictions on transport of samples and selection of patients.

Binding, Competitive↗