Acyclovir serum concentrations following peroral administration of magnetic depot tablets and the influence of extracorporal magnets to control gastrointestinal transit.

In the present investigations peroral acyclovir depot tablets with internal magnets were developed. An extracorporal magnet was used to prolong the gastric residence times of the dosage forms and to influence the duration of absorption of acyclovir. The magnetic depot tablets contained 200 mg acyclovir. In a three-way cross-over in vivo study with five healthy male subjects, the plasma concentration-time profiles of acyclovir were determined. The acyclovir plasma concentrations following peroral administration of magnetic depot tablets in the presence and absence of an extracorporal magnet were determined. A commercially available immediate release preparation was used as a reference preparation. In the presence of an extracorporal magnet which was placed in the stomach region, the plasma concentrations of acyclovir were significantly higher after 7, 8, 10 and 12 h (P<0.05, U-test, Wilcoxon, Mann-Whitney). The mean area under the plasma concentration-time-curve (AUC0-24h), in the presence of the extracorporal magnet was 2802.7 ngh/ml. Without the extracorporal magnet a mean AUC0-24h of 1598.8 ngh/ml was achieved. Computer simulations were carried out to show the influence of the gastric residence time of acyclovir depot preparations on the plasma concentration-time profiles of acyclovir. Copyright 1998 Elsevier Science B.V.