PubMed Health⌕ Search

PubMed · 6121851

In vitro dissolution of dapsone.

Abstract

Los normal samples of dapsone (DDS) were prepared in which the geometric mean diameter ranged from 20 to 50 micron while the geometric standard deviation was in the range 1.62 to 1.88. Using a simple in vitro flow-through dissolution cell at 37 degrees C, the data obtained were found to fit the Hixson-Crowell cube root dissolution law up to a critical time, Tc, where a distinct break occurred. Such a biphasic phenomenon has been predicted by other workers and is related to the time at which the smallest particles present have undergone dissolution. The initial slopes of the cube root dissolution plots were shown to be directly related to the reciprocal of the geometric mean diameter.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J Swarbrick, D Ma. 1981. In vitro dissolution of dapsone.. https://doi.org/10.1111/j.2042-7158.1981.tb13932.x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

A rapid assay for dihydropteroate synthase activity suitable for identification of inhibitors.

The enzymes 6-hydroxymethylpterin pyrophosphokinase (HPPK) and dihydropteroate synthase (DHPS) catalyze sequential steps in folate biosynthesis. They are present in microorganisms but absent in mammals and therefore are especially suitable targets for antimicrobials. Sulfa drugs (sulfonamides and sulfones) currently are used as antimicrobials targeting DHPS, although resistance to these drugs is increasing. The most widely used assay that measures activity of these enzymes, to assess new inhibitors in vitro, is not amenable to automation. This article describes a simple, coupled, enzymatic spectrophotometric assay where the product of the DHPS reaction, dihydropteroate, is reduced to tetrahydropteroate by excess dihydrofolate reductase (DHFR) using the cofactor NADPH. The oxidation of NADPH is monitored at 340 nm. The activity of both HPPK and DHPS can be measured in this assay, and it has been used to measure kinetic parameters of wild-type and sulfa drug-resistant DHPS enzymes to demonstrate the utility of the assay. It is a sensitive and reproducible assay that can be readily automated and used in multiwell plates. This NADPH-coupled microplate photometric assay could be used for rapid screening of chemical libraries for novel inhibitors of folate biosynthesis as the first step in developing new antimicrobial drugs targeting the folate biosynthetic pathway.

Dapsone↗