Intragastric long-term pH-metry in hemodialysis patients. A study with famotidine

The onset and duration of famotidine action were studied in 14 hemodialysis (HD) patients and 16 healthy controls (control group: CG) who were examined by ambulatory intragastric 24-hour pH-metry. 20 mg famotidine was administered i.v. 90 min after HD in the afternoon (AN; 2 p.m.; n = 8) or evening (E; 8 p.m.; n = 6), followed by a standard meal. Mean onset of action in the AN and E groups of the HD patients was 90.3 +/- 28.2 min and 98.8 +/- 29.8 min, and in CG patients 36.3 +/- 11.9 min and 53.6 +/- 22.3 min, respectively (p less than 0.05). Duration of action in the AN and E groups of the HD patients was 22.7 +/- 2.1 h and 21.6 +/- 2.6 h, and in CG patients 6.0 +/- 1.1 h and 11.4 +/- 1.6 h, respectively (p less than 0.05). Our study showed a retarded and prolonged action of famotidine in HD patients. The time of administration of famotidine had no effect on its action in HD patients. This is in contrast to normal subjects in whom evening administration delays the onset and prolongs the duration of famotidine action in comparison to afternoon administration.