Prolonged wireless measurement of intragastric pH and pharmacodynamics of extended-release injectable omeprazole in horses.
Hodgson Evelyn E, Thirouin Marthe M, Romano Tallia-Rume TR, Stewart Allison A et al.
Adaptation of wireless capsules for intragastric pH measurement in horses has a short, variable attachment duration. Prolonged measurement is important for pharmacodynamic studies. Extended-release injectable omeprazole (ERIO) induces acid suppression for ≤ 7 days. Five-day dosing intervals are now recommended for improved healing rates. To (1) optimize the methodology to achieve 5-7 days of capsule attachment; (2) determine whether capsules can detect a treatment effect of ERIO; and (3) describe the pharmacodynamics of ERIO. Twelve healthy adult horses. Capsules were attached transendoscopically to the glandular mucosa on day 0 using either 1 hemostasis clip (1HEM; n = 4), 4 hemostasis clips (4HEM; n = 5), or a helix tacking device (TACK; n = 9). Intragastric pH was continuously recorded and ERIO was administered on day 1. Data are reported as median (IQR). Capsules remained attached and obtained data for 51 h (42-65), 129 h (105-256), and 95 h (71-154) for 1HEM, 4HEM, and TACK, respectively. The percentage of time the pH was above 4 (%tpH > 4) was significantly higher (P < .001) on day 1 (82.0% [72.7-91.2]) than day 0 (14.3% [7.1-23.5]). Complete recordings were available for 6/12 horses throughout the 5-day dosing interval; %tpH > 4 exceeded 66% for 5 days after ERIO in 4/6 horses (66.7%). These refined, minimally invasive attachment techniques enabled longer, more consistent intragastric pH measurement. A treatment effect associated with ERIO administration was detected and %tpH > 4 exceeded 66% throughout the 5-day dosing interval in most horses.