Kinetics of absorption and elimination of ofloxacin in humans after oral and rectal administrations.

Ofloxacin pharmacokinetics have been studied in four healthy subjects after a single oral or rectal dose, each of 200 mg. For the oral dose tmax was about 2 h, Cmax 1.96 +/- 0.56 micrograms/ml and AUC1-15 15.22 micrograms/ml.h. Two-phase elimination pharmacol kinetics were observed for the oral dose, t1/2 for the rapid elimination phase was 3.3 h and for the slow phase 10 h. With the rectal dose tmax was 6 h, Cmax 0.71 +/- 0.44 microgram/ml and AUC0-15 7.58 micrograms/ml.h. The relative rectal bioavailability (AUC rectal/AUC oral) was 49.8%. Elimination rate of the rectal dose was generally slow (t1/2 = 9 h), an observation attributable to the sustained-release effect of the rectal suppository base, PEG 6000. The indication is that the rectal formulation cannot be substituted totally for the oral without first increasing the rectal dose; the 200 mg suppository can however be employed as a follow-up therapy to the oral dose in certain situations.

Colorimetric determination of the fluoroquinolones.

Ciprofloxacin, ofloxacin and norfloxacin formed an amber coloured complex with iron(III) nitrate nonahydrate. The complex, which formed instantaneously at room temperature, was stable. The solutions of the complex obeyed Beer's law at 370 nm, the wavelength of maximum absorption of radiation (lambda[max]). The A(1%) for norfloxacin, ofloxacin and ciprofloxacin was 202, 207 and 235 respectively. The formation of the complex was the basis for the quantitative and qualitative determination of the drugs. There was statistically no significant difference (P < 0.05) between the results obtained quantitatively by this colorimetric method and those obtained by the microbiological assay method.