Small Animal Clinical Pharmacology - CYF MEDICAL DISTRIBUTION

PROKINETIC DRUGS
• Dosages are empirical as no specifi c dosages have been
defi ned for animals
Tablets (e.g. aluminum hydroxide 500 mg) can be administered at
10–30 mg/kg PO q.8 h
For liquid preparations (e.g. aluminum hydroxide gel 4% w/v), usual
doses are generally in the order of 5–10 mL PO q.8 h
To be effective, antacids must be administered at least every 4 h
Adverse effects
● Calcium-containing antacids tend to promote constipation;
magnesium promotes looser feces and aluminum
reduces gastric motility and delays gastric
emptying.
● If antacids are administered infrequently they may
actually result in increased gastric acid production.
● Administration of excessive calcium-containing antacids
may predispose to renal calculi.
● Hypophosphatemia and accumulation of aluminum
are potential sequelae with long-term use of aluminum-containing
antacids.
Known drug interactions
Antacids will interfere with gastric absorption of concurrently
administered drugs such as digoxin, tetracyclines
and fluoroquinolones.
THERAPY FOR ERADICATION OF
HELICOBACTER SPP
Helicobacter pylori is the major cause of pyloric ulcer
disease in humans. A number of Helicobacter species
have been shown to colonize the gastric mucosa of cats
and dogs, including H. felis and H. heilmanii, and
gastric spiral organisms are often identified during histopathological
inspection of gastric mucosal biopsy
specimens procured from both symptomatic and asymptomatic
companion animals. Therefore, it remains controversial
as to whether or not Helicobacter species are
a significant cause of disease in small animals. Certainly,
disease is not the result of simple infection and disease
pathogenesis is likely more complicated. Instead, it is
thought that these organisms are normal commensal
bacteria and that most dogs and cats can tolerate their
presence. Current theories on the pathogenesis of
Helicobacter-associated gastritis center on the hypothesis
that disease manifests after a breakdown in mucosal
tolerance to Helicobacter species. As a consequence,
many clinicians choose to eradicate Helicobacter species
in patients with chronic vomiting and biopsy-proven
gastric inflammation.
Treatment usually involves administering a combination
of antibacterial and acid-blocking drugs. Numerous
combinations have been suggested, but those which
have been critically evaluated include the following.
● Amoxicillin (20 mg/kg PO q.12 h for 14 d), metronidazole
(20 mg/kg PO q.12 h for 14 d) and famotidine
(0.5 mg/kg PO q.12 h for 14 d) in dogs.
● Clarithromycin (30 mg PO q.12 h for 4 d), metronidazole
(30 mg PO q.12 h for 4 d), ranitidine (10 mg
PO q.12 h for 4 d) and bismuth subsalicylate (40 mg
PO q.24 h for 4 d) in H. heilmanii-infected cats.
● Azithromycin (30 mg PO q.24 h for 4 d), tinidazole
(100 mg PO q.24 h for 4 d), ranitidine (20 mg PO
q.24 h for 4 d) and bismuth subsalicylate (20 mg PO
q.12 h for 4 d) in H. heilmanii-infected cats.
● Amoxicillin (20 mg/kg PO q.8 h for 21 d), metronidazole
(20 mg/kg PO q.8 h for 21 d) and omeprazole
(0.7 mg PO q.24 h for 21 d) in H. pylori-infected
cats.
● Amoxicillin (20 mg/kg PO q.12 h for 14 d), clarithromycin
(7.5 mg/kg PO q.12 h for 14 d) and
metronidazole (10 mg/kg PO q.12 h for 14 d) in H.
pylori-infected cats.
Thus if a decision is made to eradicate Helicobacter
species, use of one of the above protocols is
recommended.
DRUG COMBINATIONS
Hyoscine and dipyrone
Spasmogesic®, Buscopan® and other trade names
describe drug combinations containing the anticholinergic
hyoscine and the NSAID dipyrone. Although this
combination is relatively commonly used in small
animals, its value in the management of gastrointestinal
disease is questionable.
The potential concerns with anticholinergic usage in
the management of vomiting or diarrhea are discussed
elsewhere in this chapter. The potential adverse effects
from dipyrone are discussed in Chapter 13 on
NSAIDs.
PROKINETIC DRUGS
Treatment of certain conditions such as delayed gastric
emptying and suboptimal colonic motility is facilitated
by the use of prokinetic drugs. These include metoclopramide
(discussed previously), ranitidine (again
described previously), erythromycin and cisapride.
Cisapride was previously the prokinetic of choice in
small animals. However, this drug was recently implicated
in causing adverse cardiac events in people. This
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