PubMed Health⌕ Search

Biomedical subjects

C Beer

Publications and source records attributed to C Beer.

7 recordsLinked to original sources
PubMed1988

4-quinolones inhibit biotransformation of caffeine.

The pharmacokinetics of caffeine, including formation of its major metabolite paraxanthine in plasma, has been investigated in 12 healthy males (age 20-40 years) alone and during co-administration of the 4-quinolones ofloxacin, norfloxacin, pipemidic acid, ciprofloxacin, and enoxacin; ciprofloxacin and enoxacin were given in 3 different dose levels. The naphthyridine derivative enoxacin and the pyrido-pyrimidine derivative pipemidic acid had caused marked inhibition of caffeine and paraxanthine metabolism, whereas the genuine quinolone derivatives norfloxacin and ciprofloxacin had little effect, and the pyrido-benzoxacine derivative ofloxacin had no detectable effect. The different molecular and spatial structures of the compounds appear to be responsible for the differences in inhibitory potency.

Adult↗
PubMed1987

Decrease of caffeine elimination in man during co-administration of 4-quinolones.

The single dose pharmacokinetics of caffeine (220-230 mg per dose) were investigated in 12 healthy male volunteers before and during treatment with ofloxacin (200 mg bd), ciprofloxacin (250 mg bd) and enoxacin (400 mg bd) with a cross-over study design. None of the parameters: mean elimination half-life (T1/2el), Cmax, total body clearance (Cltot) and the volume of distribution (aVd) of caffeine were noticeably altered by administration of ofloxacin. Striking changes were observed, however, after administration of enoxacin: the T1/2el was prolonged by as much as 260%, the Cmax increased by 41%; the aVd was reduced by 20% and Cltot by 78% (mean values). Treatment with ciprofloxacin led to a prolongation of T1/2el by 15%, to a decrease of aVd by 25% and to a 33% decrease of Cltot. The results of this intra-individual comparison of caffeine pharmacokinetic data demonstrate that treatment with ciprofloxacin and enoxacin may have a significant inhibitory effect on caffeine elimination.

Adult↗
PubMed1987

Interaction between quinolones and caffeine.

The effects of multiple doses of ofloxacin 200 mg, ciprofloxacin 250 mg or enoxacin 400 mg (all twice daily) on the pharmacokinetic properties of single doses of caffeine (220 to 230 mg) were investigated in 12 healthy volunteers. Intraindividual comparisons showed that ciprofloxacin and enoxacin significantly inhibited the elimination of caffeine. Ofloxacin, however, did not affect any of the measured pharmacokinetic properties of caffeine. Thus, caffeine should be avoided in patients with liver disorders, cardiac arrhythmias, latent epilepsy or in intensive care while undergoing treatment with enoxacin or ciprofloxacin.

Adult↗