Bioavailability of doxycycline from dissolved doxycycline hydrochloride tablets--comparison to solid form...

Doxycycline (DC) is used either as solid form hydrochloride capsules, or as monohydrate tablets, which may be taken either as solid form tablets or dissolved in water. In this single dose (150 mg), crossover study on 15 healthy volunteers, the pharmacokinetic properties of DC from hydrochloride tablets taken either in dissolved or in solid form were compared with those observed after taking dissolved DC as a monohydrate tablet. The results of this study show that DC is absorbed rapidly (tmax 3.3-3.8 h) and with equal bioavailability (AUC values 52.9-58.5 mg/l x h) from both hydrochloride and monohydrate tablets. It can be concluded that taking the DC hydrochloride tablets in dissolved form does not affect the pharmacokinetics of DC, moreover the bioavailability of DC is comparable to that achieved after taking DC monohydrate tablets in dissolved form.