Dissolution profile determination of a multicomponent product using a rapid liquid chromatographic analysis

Automated analytical systems for drug development studies. II--A system for dissolution testing

Microdialysis is a non-equilibrium dynamic sampling method in which the analytes diffuse across a semipermeable membrane due to a concentration gradient and are carried away by the constantly pumping perfusion medium for on-line analysis. A BAS, Inc. microinfusion pump/injector and an on-line LC system were interfaced with a dissolution apparatus to automate dissolution testing of tablets. A DL-5 microdialysis loop probe was suspended in the dissolution medium for sampling. The automated system was used reproducibly (RSD < 2%) to measure the dissolution of acetaminophen and Sulfatrim tablets. Drug recovery from the microdialysis probe was a function of the perfusion rate at constant temperature. However, microdialysis recovery was independent of drug concentration over the linear ranges of the assays for the analytes of interest. Dissolution profiles determined by microdialysis sampling were compared with manual sampling. Identical profiles were obtained for acetaminophen tablets in water at 37 degrees C and 50 rpm by both sampling methods. Dissolution of Sulfatrim tablets was determined in 0.1 M hydrochloride acid at 37 degrees C and 75 rpm. Microdialysis sampling permitted the use of a specially designed perfusion medium to buffer the acidic samples before injecting onto the LC column. Dissolution profiles of sulphamethoxazole were comparable for both sampling methods; however, microdialysis sampling indicated slightly higher release of trimethoprim from the Sulfatrim tablets, which was attributed to release of adsorbed drug from the connecting tubing.

A drug dissolution monitor employing multiple fiber optic probes and a UV/visible diode array spectrophotometer

A traditional dissolution pumping system was recently replaced with a fiber optic interface between the spectrometer and the samples. However, the system was limited to a single sample vessel. In this study, a dissolution testing system with six vessels connected to a diode array spectrometer via six optical fibers was investigated. A bifurcated fiber optic bundle was used to transfer the light from the source to the dissolution vessels and was networked so that spectra of each sample can be measured periodically. A full spectrum calibration method based on Principal Component Regression (PCR) was used to determine the concentrations of active ingredients and to account for interferences due to excipients in tablet formulations. Results on this new fiber optic interface system are compared with those obtained previously with the traditional pumping system. Standard errors of prediction are between 1.5 and 3.2% using cross-validation and between 1.1 and 1.7% for the direct validation of two active ingredients in two different drug formulations.

The automation of dissolution testing of solid oral dosage forms

Dissolution testing of solid oral dosage forms plays a very important part both in the development of new products and in quality control. A fully automated system for dissolution testing known as AUTO DISS is presented and its components are described. On-line determination of active ingredient concentration is possible with the aid of an integrated automatic sampler in combination with various measuring instruments (UV-vis spectrometry, liquid chromatography and flow injection analysis). The suitability of the system is demonstrated by determination of the dissolution of brotizolam from tablets by FIA and of bepafant from capsules by diode-array spectroscopy.