Morning or evening dosage of omeprazole for gastro-oesophageal reflux disease?

When routinely checking patients receiving omeprazole treatment for gastro-oesophageal reflux, we have been finding patients with surprisingly low nocturnal gastric pH. The aim of this study was to evaluate the impact of timing of the 40 mg omeprazole once daily regimen.

We evaluated the difference in effect of 40 mg omeprazole, given as a morning or evening dose, in 17 patients with gastro-oesophageal reflux disease. Gastric and oesophageal pH was recorded by portable 24-h two-channel pH-metry in a cross-over design of 14 days of morning and 14 days of evening administration.

In five patients pathological reflux was abolished by both regimens, four only during morning dosage, and three only during evening dosage. In the remaining five patients abolition of pathological reflux was not achieved. The therapeutic outcome and patient preference for morning or evening administration were closely related to the individual oesophageal pH curves. Patients with reflux induced by physical activity had a clear preference for morning dosage, patients with nocturnal reflux showed a clear preference for evening dosage. Gastric pH profiles showed a high inter-individual variation; paired statistics, however, revealed a significant impact of dosage timing on the gastric pH profile. After morning dosage the work-day part (the first 7 h) of the gastric pH profile is 0.72 +/- 0.91 (mean difference of pairs +/- s.d.) higher than after evening dosage (P < 0.01). After evening dosage the gastric pH during the supine period is 0.64 +/- 0.83 (mean difference of pairs +/- s.d.) higher than after morning dosage (P = 0.02).

The timing of a 40 mg omeprazole dosage regimen has a clinically significant impact on the 24-h pH profile, and that--by relating to the patient 24-hour oesophageal pH-metry in combination with the patient symptomatology--the timing of this dosage is highly important for therapeutic efficacy.