898
P A R T 1 1
Drugs acting on the gastrointestinal system
H
2
receptor sites
Proton pump
inhibitors work
here:
esomeprazole
lansoprazole
omeprazole
pantoprazole
rabeprazole
Pancreatic
enzyme works
here:
pancrelipase
Prostaglandin works
here:
misoprostol
Parietal cells
Antacids work here:
aluminium and
calcium salts,
magnesium salts,
sodium bicarbonate
Antipeptic agent
works here:
sucralfate
FIGURE 57.1
Sites of action of drugs
affecting gastrointestinal secretions.
Drugs that decrease acid may affect more than acid levels
In December 2005, the Journal of the American Medical
Association published a study that followed people
taking proton pump inhibitors (Nexium and others) over
a period of 10 years.The report showed that people
using these drugs had Clostridium difficile infections
leading to diarrhoea at three times the rate of people not
using these drugs.There was also a reported two-time
increase in these infections in people using histamine-2
(H
2
) antagonists (cimetidine). C. difficile is a significant
cause of diarrhoea in the community. Other studies have
reported similar findings. Drugs that lower acid levels
change the normal environment of the GI tract, perhaps
allowing bacteria to thrive that would normally be
destroyed by the acid. Most of these acid-lowering drugs
are available in over-the-counter (OTC) preparations and
may be used in excessive doses for prolonged periods of
time without the healthcare provider’s knowledge.This
information should alert healthcare providers and people
to the need for caution in using these drugs. If a person
is complaining about diarrhoea, the healthcare provider
should specifically ask about the use of acid-lowering
products (sometimes people do not even think of these
products as drugs because they can buy them without
a prescription). During healthcare teaching sessions, it
is important to remind people to read the labels of OTC
drugs carefully and to follow instructions. If a person feels
the need to take one of these products for a prolonged
period of time, they should be advised to obtain a medical
evaluation because the symptoms being treated with these
drugs could have an underlying medical cause that should
be evaluated.
When evaluating the data from the study, the
researchers also noted a similar increase in these GI
infections in people using non-steroidal anti-inflammatory
drugs (ibuprofen, ketoprofen and others) for a prolonged
period of time.The researchers suggested that further
study be done on that group of people to verify the finding.
It is important to keep current with long-term studies on
drugs and to remember that changing a normal function
or environment in the body will change the balance of
homeostasis in the body and could potentially cause other
problems. In 2007, similar studies reported an increase in
osteoporosis and bone fractures in people on long-term
proton pump inhibitor use. Changing the acidity of the GI
tract seems to affect calcium absorption. Further studies
may show other changes in homeostasis with long-term
use of these drugs.
Dial, S., Delaney, J. A., Barkun, A. N. & Suissa, S. (2005). Use of
gastric acid suppressive agents and the risk of community
acquired Clostridium difficile associated diarrhoea. JAMA, 294,
2898–2995.
Yu-Xiao,Y., Lewis, S. D, Epstein, S. & Metz, D. (2007). Long term
proton pump inhibitor therapy and risk of hip fracture. JAMA,
296, 2947–2953.
The evidence
BOX 57.2
