Metabolic and Inhibitory Interactions

The most clinically significant interaction between some fluoroquinolones and other drugs occurs with xanthine derivatives, most importantly with theophylline but also with caffeine. Inhibition of the cytochrome P450 system and resulting reduction in plasma clearance may cause nausea, vomiting, and, almost exclusively with enoxacin, convulsions during coadministration of theophylline [112]. The reduction in clearance is most pronounced with enoxacin and grepafloxacin, less so with pefloxacin and ciprofloxacin, and either absent or insignificant (<10%) with later derivatives [108,113,114]. Neither sparfloxacin, levofloxacin, trovafloxacin, moxifloxacin, nor gatifloxacin significantly inhibit theophylline metabolism [34]. Enoxacin must not be coadministered with theophylline, and dosage of the latter, especially the intravenous form, should either be discontinued or closely monitored (with appropriate modification) during coadministration of ciprofloxacin or pefloxacin. Fluoroquinolones also interfere with caffeine metabolism via similar mechanisms, and both resultant sleep disturbance and upper gastrointestinal symptoms may be clinically apparent [108].

Synergistic inhibition of CNS GABA receptors by fluoroquinolones and NSAIDs may cause neuroexcitatory phenomena. The effects of fluoroquinolones on the GABA receptor are dose dependent and vary between group members, the ability of which to induce convulsions in mice when combined with biphenyl acetate (the active metabolite of fenbufen) is also quite different [115]. In man, convulsions have only been reported in Japanese patients receiving both enoxacin and fenbufen [116]. The interaction between NSAIDs and other (notably, newer-generation) fluoroquinolones may be of little clinical significance [34].

Coping with Asthma

Coping with Asthma

If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.

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