Predicting the ciprofloxacin‐theophylline interaction from single plasma theophylline measurements.

Abstract

The effect of ciprofloxacin treatment on theophylline clearance was evaluated with a theophylline multiple dose, multiple sample protocol and with a single dose, single sample protocol. The object was to determine whether a single dose, single sample protocol for estimating theophylline clearance could be used as a screening strategy for evaluating host factor influences on theophylline clearance. Ciprofloxacin (750 mg per os) was administered every 12 h for nine doses in the multidose study and every 12 h for seven doses in the single dose protocol. Subjects were sixteen healthy, non‐smoking young adult males. The oral clearance of theophylline at steady state, (CL/F)ss, decreased from a mean (+/‐ s.d.) value of 0.035 (+/‐ 0.008) 1 h‐1 kg‐1 to 0.024 (+/‐ 0.004) 1 h‐1 kg‐1 during ciprofloxacin treatment. Single sample estimates of theophylline clearance, CL/F, similarly decreased from 0.040 (+/‐ 0.014) 1 h‐1 kg‐1 to 0.018 (+/‐ 0.008) 1 h‐1 kg‐1. Mean theophylline clearances were significantly different when comparing control with ciprofloxacin treatment means (P less than 0.01), but were not different when comparing single sample vs multiple sample clearances for a given treatment (i.e. control or ciprofloxacin). It is concluded that a single dose, single sample strategy may be used in screening for host‐factor influences on theophylline clearance.