The effects of famotidine, ranitidine and magnesium hydroxide/aluminium hydroxide on gastric fluid pH in adult horses.

The study investigates the impact of three different gastric medications – famotidine, ranitidine, and a magnesium hydroxide/aluminium hydroxide antacid – on the acidity of gastric fluid in adult horses, by measuring the pH levels in their stomachs.

Methods and Materials

The research was conducted on five adult horses, each given different doses of the three medications via a nasogastric tube. The drugs administered were:

• Famotidine at doses of 0.5, 1.0, and 2.0 mg/kg body weight.
• Ranitidine at doses of 4.4 and 6.6 mg/kg body weight.
• Antacid containing magnesium hydroxide and aluminium hydroxide, at volumes of 120 and 180 ml.

Closely following the administration of the medications, gastric fluid was aspirated from the horses at 15-minute intervals and its pH was measured, providing information about the level of acidity within the horse’s stomach.

Basal Gastric Fluid pH

Prior to administering the treatments, the horses were observed for six hours each under normal conditions, and the pH of the gastric fluid was measured regularly. The average basal gastric pH (a measure of acidity prior to any treatment) was around 1.88, implying high acidity, with only two outlier measurements.

Medications and pH Changes

The horses responded variably to both famotidine and ranitidine. With minor differences, the recorded pH levels reflected a decrease in acidity after a single dose of both famotidine and ranitidine. However, the variations between different dosages were not statistically significant. In addition, gastric fluid pH increased to greater than 6 (less acidic) in some horses from each group. Among all horses, ranitidine showed a tendency to maintain a pH above 6 for longer than famotidine, though the difference was marginal.

Response to Antacid

The response to the antacid was inconsistent and transient. There was only a minor increase in pH after both 120 ml and 180 ml doses, and the pH rose to greater than 6 in just two horses, but only briefly.

Conclusions

From the results, it was observed that the increase in gastric fluid pH was significantly greater for ranitidine, and to a lesser extent famotidine, than for the antacid. Correspondingly, the duration of the effect was observed to be significantly longer for ranitidine dosages than for the antacid. Besides, famotidine also showed a trend towards a longer duration, though not statistically significant. This suggests that ranitidine and famotidine might be more effective than the antacid studied in managing gastric acidity in horses.