A dose‐effect study of the in vivo inhibitory effect of quinidine on sparteine oxidation in man.

MD Nielsen*, K. Brosen, LF Gram

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

1. Twelve healthy extensive metabolisers of sparteine were sparteine tested daily for 6 days (19.00 h to 07.00 h). A small but statistically significant rise in sparteine metabolic ratio (MR) was observed. 2. Following 100 mg quinidine sulphate given to four of the subjects at 16.00 h, sparteine tests were carried out 19.00 h to 07.00 h on the same day and then daily for 6 days. Quinidine caused an immediate twenty‐fold increase in sparteine‐MR which then gradually returned to normal over the following 4‐6 days. Quinidine concentrations in plasma were measurable only up to 20 h after the quinidine test dose. 3. At weekly intervals, all 12 subjects received single doses of quinidine sulphate of 5, 10, 20, 40 and 80 mg at 16.00 h, each time followed by a sparteine test 19.00 h to 07.00 h on the same day. A clear dose‐effect relationship was found with a significant rise in the sparteine‐MR even after 5 mg quinidine. After 80 mg quinidine, 8 of 12 subjects became phenotypically poor metabolisers (MR greater than 20). 1990 The British Pharmacological Society

Original languageEnglish
JournalBritish Journal of Clinical Pharmacology
Volume29
Issue number3
Pages (from-to)299-304
Number of pages6
ISSN0306-5251
DOIs
Publication statusPublished - 1. Jan 1990

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