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Biomedical subjects

B W Hadzija

Publications and source records attributed to B W Hadzija.

12 recordsLinked to original sources
PubMed1996

Comparison of cosmetic and physicochemical properties of six topical corticosteroid creams.

The cosmetic and physicochemical properties of six topical corticosteroid creams were evaluated and compared. The following creams were provided in blinded tubes: Elocon, Westcort, Lidex, Kenalog, Valisone, and Cutivate. The following properties were evaluated in vitro: stiffness (hardness), grittiness, color, odor, homogeneity (phase separation), pH, weight loss, and tackiness (stickiness). Samples of the creams were evaluated by light microscopy and scanning electron microscopy to identify particle and droplet distribution, particulate contamination, and microscopic homogeneity of the products. Cutivate ranked number 1 in each category and received the best overall score for each of the cosmetic and physicochemical properties evaluated. The cosmetic and physicochemical properties of Elocon, Westcort, Lidex, and Kenalog were found to be similar to one another with regard to overall score but inferior to Cutivate. Valisone was also good with regard to overall score but was ranked less acceptable due to a strong odor.

Administration, Topical↗
PubMed1994

High-performance liquid chromatographic method for the simultaneous determination of low-molecular-mass oligomers of polyethylene glycol in aqueous skin extracts.

The isocratic, reversed-phase, high-performance liquid chromatographic (HPLC) method presented provides a simple and rapid analytical technique for the simultaneous determination of low-molecular-mass oligomers of polyethylene glycol (PEG) in aqueous polymer samples containing polar contaminants of biologic origin. In the present case, individual molecular mass species were quantitated in aqueous skin extracts arising from the investigation of PEG transport through mammalian skin. PEGs were isolated and purified by solid-phase extraction using large-pore kieselguhr (Extrelut QE) cartridges, which selectively retained polar contaminants from excised skin specimens. Sample recoveries were found to be dependent upon molecular mass, ranging from 18.28% to 86.10%, but were highly reproducible. The mean inter-sample error (n > or = 5) for the extraction of twenty-six molecular mass species of PEG was less than 3%. Satisfactory resolution of primary molecular mass components was accomplished using a base-deactivated, C8 column (Supelcosil LC-8-DB) and a mobile phase consisting of methanol and water. Corresponding run times for the complete separation of individual oligomers ranged from 8 to 30 min, while the limit of detection for a particular molecular mass species was approximately 5 micrograms/ml. The method was further employed to determine the weight-average (Mw) and number-average (Mn) molecular mass distributions and polydispersity for three commercial PEG blends, as well as to characterize the methylene chloride/water distribution coefficients for twenty-two molecular mass species ranging from 282 to 1206 Da.

Animals↗
PubMed1992

Effect of freezing on iontophoretic transport through hairless rat skin.

The influence of frozen storage of hairless rat skin on the constant-current iontophoretic transport of a model weak acid, salicylic acid, was examined. Nearly a threefold increase was observed in the steady-state flux of salicylic acid through previously frozen skin (217.1 nmol h-1 cm-2) when compared with fresh, excised skin (72.3 nmol h-1 cm-2). The iontophoretic permeability of skin to salicylic acid was also found to be dependent upon the length of time skin samples remained in the frozen state. Differential scanning calorimetry studies revealed distinct differences in the thermograms for fresh and frozen skin. These results suggest that storage of skin samples in the frozen state may contribute to physical or chemical changes in skin structure.

Animals↗
PubMed1992

Iontophoretic permeability of polyethylene glycols through hairless rat skin: application of hydrodynamic theory for hindered transport through liquid-filled pores.

The electrically-assisted transport of a homologous series of polyethylene glycols (PEGs) through hairless rat skin (HRS) was examined in order to determine the relationship between the iontophoretic permeability of flexible macromolecules and their size and conformation in free solution. Using fully hydrated HRS, the anodic transport of 26 low molecular weight oligomers of PEG was studied over a 14 hour period at a current density of 0.50 mA/cm2. Analysis of the data revealed a distinct sigmoidal relationship between iontophoretic permeability and molecular size. In addition, the reflection of a relatively small molecular weight species was significant. Accordingly, a hydrodynamic model relating the convective transport of flexible macrosolutes through cylindrical pores was fit to the data generated from the iontophoretic transport of PEGs ranging in weight from 282 to 1382 daltons. A nonlinear least squares analysis of the data demonstrated that the 'effective' mean diameter of aqueous channels within HRS is approximately 36 A.

Animals↗
PubMed1988

Physicochemical stability of papaverine hydrochloride-phentolamine mesylate mixtures used for intracavernous injection: a preliminary evaluation.

Physicochemical stability of intracavernous injections of 30 mg. per ml. papaverine hydrochloride with 0.5 or 1.0 mg. per ml. phentolamine mesylate used to induce erection in patients with impotence was examined. The samples were stored at room temperature, in the refrigerator at 4C and in the freezer at -20C for 6 months. The examination consisted of visual observation for change in color or evidence of precipitation, measurement of pH and thin layer chromatography at different intervals. During the 6 months of storage no change had occurred in pH, color development, precipitation or formation of new moieties. Therefore, the aforementioned injection solutions of papaverine hydrochloride with phentolamine mesylate can be dispensed safely with instruction to patients for adequate storage and manipulation.

Drug Combinations↗
PubMed1987

Bioavailability of controlled-release metoclopramide. 1st communication: single dose study.

The bioavailability of metoclopramide monochloride hydrate after single dose oral administration of a controlled-release capsule (Gastro-Timelets) was compared with that of oral metoclopramide monochloride hydrate solution in four normal volunteers. 30 mg of each product was administered to each subject in a cross-over manner on two separate occasions and plasma metoclopramide levels were measured using a HPLC method. Although peak plasma metoclopramide concentrations were lower, and occurred later after capsule treatment than after solution, analysis of the area under the plasma concentration-time curve (AUC) values for the two formulations demonstrated that the products were equivalent in terms of the extent of absorption, with the mean AUC value (0-30 h) for the capsule 943.7 ng/h/ml and that for the solution 896.2 ng/h/ml.

Adult↗
PubMed1987

Bioavailability of controlled-release metoclopramide. 2nd communication: multiple dose study.

The bioavailability of metoclopramide monochloride hydrate after oral multidose administration of controlled-release metoclopramide capsules (Gastro-Timelets) was compared with that of oral metoclopramide monochloride hydrate solution in 10 healthy men. 30 mg of each product was administered to each subject in a cross-over fashion for 5 consecutive days and the plasma metoclopramide concentration was measured using a HPLC assay. Peak plasma metoclopramide levels were lower, and occurred later after controlled-release capsules administration than after solution. The graphs representing plasma metoclopramide levels after controlled-release formulation were smooth and devoid of sharp peaks and troughs. The area under the plasma metoclopramide level-time curve (AUC) values showed that the products were bioequivalent with the mean AUC values for the capsule (0-24 h) 837.9 ng/h/ml and (120-150 h) 993.2 ng/h/ml; and for the solution (0-24 h) 878.8 ng/h/ml and (120-150 h) 1054.0 ng/h/ml.

Adult↗
PubMed1978

Quantitative TLC determination of propranolol in human plasma.

A spectrodensitometric assay was developed for propranolol based on measurement of the absorbance of the drug on silica gel plates irradiated at 822 nm. Quantities as low as 0.10 microgram can be detected, and a linear relationship was obtained between 0.010 and 0.400 microgram. The percent recovery from plasma spiked with known amounts of the drug was 90.0--102.0. This procedure was used to determine propranolol in the plasma of patients receiving therapeutic doses of the drug.

Chromatography, Thin Layer↗
PubMedDate not supplied

Bioavailability of a commercial sustained-release quinidine tablet compared to oral quinidine solution.

The bioavailability of quinidine sulfate after oral administration of a commercial sustained-release quinidine tablet was compared with that of oral quinidine sulfate solution in 18 normal subjects. Three hundred milligrams of each product was administered to each subject in standard cross-over fashion on separate occasions, with plasma quinidine levels measured for 46 h after each dose. Although peak plasma quinidine levels were lower, and occurred later, after tablet administration than after solution, analysis of the area under the plasma quinidine level-time curve (AUC) values for each product indicated that the products were equivalent, in terms of the extent of absorption, with the mean AUC (0-46 h) value for the tablet, 8744 . 4 ng x h ml-1, comparable to that of the solution, 9145 . 9 ng x h ml-1.

Administration, Oral↗
PubMedDate not supplied

Simple techniques to detect and identify phentermine adulteration.

Phentermine capsules labelled Ionamin were suspected of being counterfeit. Examination of the contents revealed no phentermine, but caffeine and phenylpropanolamine. The usual microcrystalline and spectrodensitometry was used to confirm results of spectrophotometric identity tests.

Chromatography, Thin Layer↗