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Biomedical subjects

W Feinstein

Publications and source records attributed to W Feinstein.

4 recordsLinked to original sources
PubMed1981

Test for reproducibility of metered-dose aerosol valves for pharmaceutical solutions.

Seven independent testing sites received metered-dose aerosols containing a standard test solution to assess a newly designed protocol for studying the reproducibility of metered-dose aerosol valves. In accordance with the rather small sampling protocol design, the amount of product dispensed per actuation was measured over the life of the aerosol at designated regions of actuation. A statistical analysis of the data collected at each testing site clearly indicated that the testing protocol is sufficiently reliable and workable for assessing the reproducibility of valve delivery for a given lot of metered-dose valves.

Administration, Inhalation↗
PubMed1975

Development and evaluation of a dexamethasone timed-release aerosol formulation.

Dexamethasone microcapcules were prepared and in vitro parameters were determined by sieve analysis which yielded materials retained on Nos. 80-, 100-, 200-, and 270-mesh sieves. Release rate and direct total determinations indicated that some measure of timed release appeared in all four sieve samples. The pH-release rate profiles of the microcapsules indicated that dissoution was pH independent. Colloidal silica and isopropyl myristate formulations provided the best suspending characteristics of all aerosol formulations evaluated. Delivery rate, pressure, and evacuation testing demonstrated the usability and functionality of the aerosol. An evaluation was made on the effect on urinary excretion levels of 17-hydroxycorticosteroid when a physical admixture of the drug and timed-release microcapsules were sprayed on rabbits. The significantly higher 17-hydroxycorticosteroid levels obtained in urine of animals treated with the admixture after 1 day may have been attributed to both an immediate suppression of the endogenous steroid and the "spilling over" of excess dexamethasone. A significant difference also was found at the 90% confidence level among the 24, 48, and 72-hr 17-hydroxycorticosteroid levels in the admixture and the microcapsules, which substantiated the delayed effect of the latter.

Aerosols↗
PubMed1975

Determination of 17-hydroxycorticosteroids in human urine.

A study was undertaken to develop a method that could be used an an indication of the absorption of steroids. It was demonstrated that 17-hydroxycorticosteroids in urine could be quantitatively determined via absorptivity values obtained through the use of standard hydrocortisone-alcohol solutions or standard solutions of hydrocortisone in urine utilizing the blue tetrazolium assay method. This method is dependent upon the hydrolysis of conjugated urinary steroids by beef liver glucuronidase. The resultant concentration of 17-hydroxycorticosteroids is determined colorimetrically using blue tetrazolium.

17-Hydroxycorticosteroids↗