Biomedical subjects

A Loper

Publications and source records attributed to A Loper.

4 recordsLinked to original sources

PubMed1996

A new approach to the safety assessment of pharmaceutical excipients. The Safety Committee of the International Pharmaceutical Excipients Council.

This article presents a set of proposed guidelines for the safety assessment of new pharmaceutical excipients. These guidelines were developed by the Safety Committee of the International Pharmaceutical Excipients Council and represent a new, scientifically based approach to establishing conditions for the safe use of proposed pharmaceutical excipients utilizing various routes of human exposure. They are based upon the best currently available toxicological science and have taken the deliberations of the International Conference on Harmonization into consideration. These guidelines were developed because there are no regulatory agency guidelines currently available which specifically address the toxicological testing of a material intended for use as an excipient in pharmaceutical preparations. Only materials which have been previously permitted for use in a pharmaceutical preparation or which have been permitted for use in foods may be considered safe under current practices. If implemented, these guidelines should expedite the review of a proposed new excipient by regulatory agencies.

Chemistry, Pharmaceutical↗

PubMed1982

Nitrogen-phosphorous detection of phencyclidine in blood serum.

A method for quantitating phencyclidine in the blood serum of rhesus monkeys with a solvent extraction procedure followed by gas chromatography with nitrogen-phosphorous detection is reported. Phencyclidine was extracted with ether from 0.5 ml of serum (pH 13.5) made basic with 2M NaOH, followed by back-extraction into 0.5 M sulfuric acid. After the addition of 2 M sodium hydroxide, phencyclidine was extracted into a small volume of ether for concentration and injection into the gas chromatograph. The limit of quantitation of phencyclidine in serum was 5 ng/ml. Recovery averaged 51.9 +/- 4.3%. Standard curves were linear between 5-50 ng/ml and 100-2000 ng/ml. Comparison between serum and aqueous standards indicated no interference by serum components in the extraction procedure. Pentobarbital, caffeine, and the monohydroxy metabolites of phencyclidine did not interfere with the analysis. This procedure is a rapid and sensitive method for determination of serum phencyclidine levels in animal studies requiring analysis of large numbers of samples.

Animals↗

PubMed1980

Correlation of in vivo bioavailability of erythromycin stearate tablets with in vitro tests.

Correlations between the bioavailability parameters for erythromycin stearate tablets from five manufacturers and in vitro tests of these tablets were examined using forward (stepwise), multiple linear regression analysis. Bioavailability parameters were determined in clinical studies employing a balanced, incomplete block design. In vitro tests used disintegration, dissolution, and dissolution/dialysis as the independent variables in regression equations. Significant correlations were found between linear combinations of these parameters and the time of peak and the peak serum levels. The inclusion of an in vitro disintegration test to describe peak serum levels of erythromycin is noteworthy since it has been suggested that disintegration tests are of less value than dissolution techniques employed in the present investigation may be useful for selection of appropriate physicochemical tests for continued monitoring of the bioavailability of erythromycin stearate tablets.

Biological Availability↗

PubMed1979

Solvent system effects on drug absorption.

The in situ rat gut technique was used to determine 14-C salicylic acid absorption from aqueous solutions containing 20% glycerol, 20% propylene glycol, 10% ethanol, and 20% polyethylylene glycols (PEG) 4000 and 6000. A phosphate buffer solution of salicylic acid served as a control. Observed rate constants for disappearance of activity from the gut are 0.031 min-1 for glycerol, 0.0327 min-1 for PEG 6000, 0.0395 min-1 for propylene glycol, 0.475 min-1 for polyethylene glycol 4000, 0.0558 min-1 for ethanol, and 0.0752 min-1 for the control. The rate of disappearance from the gut is significantly slower than control for 20% glycerol, PEG 4000 and PEG 6000 solutions (p less than or equal to 0.01). Activity disappears more rapidly from 10% ethanol solutions than from PEG 6000 and glycerol (p = 0.01). Water flux into and out of the intestinal lumen was estimated from tritiated inulin concentrations in the perfusate. A trend for increased loss of activity from ethanol and control solutions associated with net water efflux from the intestine was observed. These results suggest that the composition of drug delivery systems may significantly affect the absorption of drugs from solution.

Animals↗