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Evaluating antacid therapy in cats with CKD

Gould E, Klos J, Price J, Harris T, Vaden S, et al. Retrospective analysis of the effect of acid-suppressant therapy on clinicopathologic parameters of cats with chronic kidney disease. J Feline Med Surg. 2018 Jun;20(6):520-527.
(A Winn-funded study)

Chronic kidney disease (CKD) is associated with a decrease in stomach pH (increase in acidity) in humans and dogs. CKD is a very common disease of cats, though some controversy exists as to whether or not it is associated with gastric hyperacidity. Proton-pump inhibitors (PPIs) have been shown to be the most effective option to increase the stomach pH. In humans, cats, and dogs these are very sae in the long term, however recent human reports have shown a link between long-term use of PPIs and worsening or development of kidney disease. Determining if PPIs have an effect on progression of CKD in cats is important due to the common prescription of these medications to cats with renal disease.

The purpose of this study was to determine if there was an effect on renal parameters in cats with CKD-prescribed PPIs, H2-blockers, or combined therapy when compared to cats with no therapy. The study was designed as a retrospective cohort study of cats diagnosed with CKD in a teaching hospital from 2005 to 2016.

Cats with CKD were staged by IRIS guidelines, but not substaged. They were also classified by antacid therapy as above. Age, sex, type and duration of acid-suppressant administration were also recorded, as were serum biochemical and CBC data prior to starting therapy and at the last recorded date. As not every treatment was received by each IRIS stage, cats were grouped into “early” (IRIS 1-2) or “late” (IRIS 3-4) CKD.

At total of 89 cats were included in the study. 62 cats were in the early group and 27 in the later group. 45% of cats were male, and 91% were older than 7 years. 98% of cats had a concurrent disease. Concurrent therapies included beta blockers, ACE inhibitors, phosphate binders, steroids, and diuretics.

Cats received the following acid suppressant therapies:

  • PPI alone- 7 cats
  • H2 Blocker alone- 30 cats
  • Combination- 6 cats
  • No suppressant- 36 cats

Most cats received omeprazole as the PPI, thought the formulation varied significantly. The most common H2 blocker was famotidine, though four cats received ranitidine.

Of cats treated with acid suppressant therapy, 64% were treated for more than 2 months, with the rest for less than 2 months.

The main outcomes variables were changes in blood parameters from initiation of therapy to the last recorded measurement. Serum creatinine concentration increased significantly with time regardless of therapy. No change to the rate of increase was seen between groups.

Serum sodium concentration was found to increase by ~2% in cats receiving PPI therapy. For some, this resulted in the cats becoming mildly hypernatremic. In early stage cats receiving combination therapy, serum magnesium dropped by 50% over the course of the study. This resulted in hypomagnesemia in several cats. No differences were seen in calcium (Ca) or potassium (K) concentrations.

The authors suggested several potential causes for increased sodium (Na) in the PPI group but were unable to determine a definitive cause. Hypomagnesemia is a well-described effect of PPI therapy in humans, however as only 2 cats were in the early combination therapy group, and total rather than ionized Mg was measured, this change may not be significant.

The retrospective nature of this study was a potential limitation, and further data in a prospective design may help to further investigate this area. The sample size was relatively small given the large number of variables at play and potential for confounding by age, drug choice, concurrent drugs, disease stage, concurrent disease, and other factors.

The authors concluded that antacid therapy does not affect the progression of CKD in cats with renal disease, and that these drugs are well tolerated in cats. They recommend monitoring of sodium in cats on chronic PPI therapy. (MRK)

See also:

Parkinson S, Tolbert K, Messenger K, et al. Evaluation of the effect of orally administered acid suppressants on intragastric pH in cats. J Vet Intern Med. 2015; 29: 104–112.

Gould E, Clements C, Reed A, et  al. A prospective, placebo-controlled pilot evaluation of the effect of omeprazole on serum calcium, magnesium, cobalamin, gastrin concentrations, and bone in cats. J Vet Intern Med. 2016; 30: 779–786.