Ciprofloxacin
Ciprofloxacin. Fluoroquinolone — inhibits bacterial DNA gyrase + topoisomerase IV. Strong CYP1A2 inhibitor (raises caffeine, theophylline… Oral half-life 4 h.
Fluoroquinolone — inhibits bacterial DNA gyrase + topoisomerase IV. Strong CYP1A2 inhibitor (raises caffeine, theophylline, tizanidine, clozapine). Black-box: tendinopathy + Achilles rupture, peripheral neuropathy, aortic aneurysm.
PK: another correct-value-wrong-paper. The half-life of 4 h is verbatim in Wingender 1984 (PMID:6489326) — "The elimination half-life was about 4 h and the renal clearance was 4.75 ml/min . kg; both were independent of the route of administration", which also settles the route question affirmatively — while the CITED paper says 3.2 h and that oral is shorter still. V 200 L was never stated in any unit: it is 2.76 L/kg silently converted at an undeclared 72.5 kg. Replaced by the same paper Vss, "the total volume at steady state was 2.0 l/kg" (140 L at 70 kg), a true intravenous volume. F corrected 0.84 to the stated 83.7% — and that figure is scoped to a 100 mg dose. BIOAVAILABILITY IS GENUINELY CONTESTED AND DOSE-DEPENDENT: 83.7% at 100 mg, about 60% at 250 mg, 82% at 500 mg in patients with AIDS. Food reduces absorption 15-20%. ka 1.5 dropped; absorption carries a lag that LENGTHENS with dose, 0.34 to 0.53 h. INTERACTIONS: THE TIDIEST BLOCK FOUND SO FAR — all five affinities reconstruct from one assumed concentration of 7.5 µM, DESPITE BEING DERIVED FROM THREE DIFFERENT KINDS OF REPORTED QUANTITY: an exposure rise, two separate clearance falls correctly inverted as reciprocals, and a doubled concentration from a pair of case reports. That internal consistency is what distinguishes a coherent single-inhibitor model from a set of independent guesses, and it is also why the block can be relabelled rather than rebuilt. ONE CAVEAT CARRIED FROM ITS OWN NOTE: the clozapine edge rests on TWO CASE REPORTS rather than a controlled crossover, and case reports do not support a quantitative constant however cleanly the algebra fits.
Pharmacokinetics
- Oral — t½ 4 h · F 84% · Vd 140 L
- IV — t½ 4 h · F 100% · Vd 140 L
Related compounds
- Theophylline — major
- Tizanidine — contraindicated
- Caffeine — caution
- Ropivacaine — caution
- Clozapine — caution
Sources: PMID:2729942, PMID:12610740, PMID:19067475, PMID:6489326