Comparative bioavailability of norfloxacin tablets based on blood and urine data.
OBJECTIVE
To assess the bioavailability of norfloxacin from urinary excretion relative to plasma concentration.


METHODS
Twelve healthy volunteers (22-33 years) participated in the study. Each received a previously developed (M), a local (L) and a multinational (Noroxin) tablet (Ref), 400 mg each, according to a random balanced three-way crossover design on 3 different days. Blood samples were collected over a 12-hour period and urine over a 24-hour period. Norfloxacin concentrations were analyzed by a validated HPLC method.


RESULTS
An initial estimate of bioequivalence of the three products was obtained using analysis of variance on transformed data and based on confidence interval calculation. Elimination pharmacokinetic parameters (half-life and renal clearance) calculated from plasma concentration and urinary excretion data (mean values, n = 36) were comparable to reported values for norfloxacin. Interproduct differences in elimination parameters (mean values, n = 12) were statistically insignificant (F values, ANOVA). Strong association was found between the mean of plasma concentration and urinary excretion rates for many volunteers (F values, regression analysis). Relative bioavailability values calculated for the local and previously developed products relative to Noroxin were higher than 85% based on area under the curve and urinary excretion. Bioequivalence could not be established among the three tested products based on calculated 90% confidence intervals.


CONCLUSIONS
Urinary excretion of norfloxacin may be a useful noninvasive tool for bioavailability assessment of norfloxacin oral formulations.
Nada
Aly H
AH
Department of Pharmaceutics, Faculty of Pharmacy, Kuwait University, Kuwait. alynada@hsc.edu.kw
Sharaf
Mohamed A
MA
El Gholmy
Zeinab A
ZA
Khalafallah
Nawal M
NM
D000328:Adult; D000890:Anti-Infective Agents / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D019540:Area Under Curve; D001682:Biological Availability; D018592:Cross-Over Studies; D004339:Drug Compounding; D005240:Feasibility Studies; D006801:Humans; D008297:Male; D009643:Norfloxacin / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D012016:Reference Values; D013607:Tablets
D000890:Anti-Infective Agents; D013607:Tablets; D009643:Norfloxacin