Automated liquid chromatographic determination of ranitidine in microliter samples of rat plasma.

An improved high-performance liquid chromatographic method with UV detection at 313 nm has been developed for quantitation of ranitidine in 100 microliter of rat plasma over the range 25 to 1000 ng/ml. To each sample were added the internal standard (metiamide) and 2 M NaOH. After dichloromethane extraction, the nitrogen-dried extracts were reconstituted in the mobile phase of 0.

Determination of azelastine and desmethylazelastine in human plasma by high-performance liquid chromatography.

A manual-injection liquid chromatographic method using fluorescence detection permitted determination of a new antiasthmatic drug, azelastine, and its desmethyl metabolite extracted from human plasma. Reliable quantitation was achieved to at least 0.3 ng/ml for each analyte.

The comparative potency of phenobarbital and five 1,3-propanediol dicarbamates for hepatic cytochrome P450 induction in rats.

Using a reproducible screening procedure for rat liver cytochrome P450 isoenzyme induction/inhibition, five dicarbamate drugs (meprobamate, mebutamate, carisoprodol, tybamate, and W-554) were compared with sodium phenobarbital and found to be from 25 to 100 times less potent hepatic cytochrome P450 inducers than phenobarbital.

Drug level monitoring of antiasthmatic drugs.

In general assays pertaining to drug level monitoring (DLM) of antiasthmatic agents (except theophylline), published during the period 1978-1983, used mostly high-performance liquid chromatographic (HPLC) methodology (approximately 45%) with mass spectrometric (MS) based assays in second place (approximately 30%) followed by immunochemical techniques (approximately 25%). Whenever nanogram or subnanogram antiasthmatic drug concentrations had to be measured such as for the adrenergic stimulants or for the prophylactic agents, then both HPLC-and MS-based methodologies were employed with about equal frequency. The trend in DLM for the phosphodiesterase inhibitor class (theophyllines) seemed to be shifting towards the HPLC methodologies.