Treatment of constipation at community pharmacy

Constipation is a condition that is difficult to define and is often self diagnosed
by patients. Generally it is characterised by the passage of
hard, dry stools less frequently than the person’s normal pattern. It is
important for the pharmacist to find out what the patient means by
constipation, and to establish what (if any) change in bowel habit has
occurred and over what period of time.

Significance of questions and answers

Details of bowel habit

Many people believe that a daily bowel movement is necessary for

good health and laxatives are often taken and abused as a result. In

fact, the normal range may vary from three movements in 1 day to

three in 1 week. Therefore an important health education role for the

pharmacist is in reassuring patients that their frequency of bowel

movement is normal. Patients who are constipated will usually com-
plain of hard stools which are difficult to pass and less frequent than
usual.
The determination of any change in bowel habit is essential, particularly
any prolonged change. A sudden change, which has lasted for
2 weeks or longer, would be an indication for referral.

Associated symptoms

Constipation is often associated with abdominal discomfort, bloating
and nausea. In some cases constipation can be so severe as to obstruct
the bowel. This obstruction or blockage usually becomes evident by
causing colicky abdominal pain, abdominal distension and vomiting.
When symptoms suggestive of obstruction are present, urgent referral
is necessary as hospital admission is the usual course of action. Constipation
is only one of many possible causes of obstruction. Other
causes such as bowel tumours or twisted bowels (volvulus) require
urgent surgical intervention.

Blood in the stool

The presence of blood in the stool can be associated with constipation
and although alarming, is not necessarily serious. In such situations
blood may arise from piles (haemorrhoids) or a small crack in the skin
on the edge of the anus (anal fissure). Both these conditions are
thought to be caused by a diet low in fibre that tends to produce
constipation. The bleeding is characteristically noted on toilet paper
after defecation. The bright red blood may be present on the surface of
the motion (not mixed in with the stool) and splashed around the
toilet pan. If piles are present, there is often discomfort on defecation.
The piles may drop down (prolapse) and protrude through the anus.
A fissure tends to cause less bleeding but much more severe pain on
defecation. Medical referral is advisable as there are other more
serious causes of bloody stools, especially where the blood is mixed
in with the motion.

Bowel cancer

Large bowel cancer may also present with a persisting change in bowel
habit. This condition kills about 20 000 people each year in the UK.
Early diagnosis and intervention can dramatically improve the prognosis.
The incidence of large bowel cancer rises significantly with age.
It is uncommon among people under 50 years. It is more common
amongst those living in northern Europe and North America compared
with southern Europe and Asia. The average age at diagnosis is
60–65 years.

Diet

Insufficient dietary fibre is a common cause of constipation. An impression
of the fibre content of the diet can be gained by asking what
would normally be eaten during a day, looking particularly for the
presence of wholemeal cereals, bread, fresh fruit and vegetables.
Changes in diet and lifestyle, e.g. following a job change, loss of
work, retirement or travel, may result in constipation. An inadequate
intake of food and fluids, e.g. in someone who has been ill, may be
responsible.

Medication

One or more laxatives may have already been taken in an attempt to
treat the symptoms. Failure of such medication may indicate that
referral to the doctor is the best option. Previous history of the use
of laxatives is relevant. Continuous use, especially of stimulant laxatives,
can result in a vicious circle where the contents of the gut are
expelled, causing a subsequent cessation of bowel actions for 1 or 2
days. This then leads to the false conclusion that constipation has
recurred and more laxatives are taken, and so on.
Chronic overuse of stimulant laxatives can result in loss of muscular
activity in the bowel wall (an atonic colon) and thus further constipation.

Treatment timescale

If 1 week’s use of treatment does not produce relief of symptoms, the

patient should see the doctor. If the pharmacist feels that it is only

necessary to give dietary advice, then it would be reasonable to leave it

for about 2 weeks to see if the symptoms settle.

Management

Constipation that is not caused by serious pathology will usually

respond to simple measures, which can be recommended by the

pharmacist: increasing the amount of dietary fibre; maintaining fluid

consumption; and taking regular exercise. In the short term, a laxative

may be recommended to ease the immediate problem.

Stimulant laxatives (e.g. senna, bisacodyl)

Stimulant laxatives work by increasing peristalsis. All stimulant laxatives

can produce griping/cramping pains. It is advisable to start at the

lower end of the recommended dosage range, increasing the dose if

needed. The intensity of the laxative effect is related to the dose taken.

Stimulant laxatives work within 6–12 h when taken orally. They

should be used for a maximum of 1 week. Bisacodyl tablets are

enteric-coated and should be swallowed whole because bisacodyl is

irritant to the stomach. If it is given as a suppository, the effect usually

occurs within 1 hour and sometimes as soon as 15 min after insertion.

Docusate sodium appears to have both stimulant and stoolsoftening

effects and acts within 12 days.

The use of senna pods and cascara, which is non-standardised,

should be discouraged because the dose, and therefore action, are

unpredictable. Castor oil is a traditional remedy for constipation,

which is no longer recommended since there are better preparations

available.

Bulk laxatives (e.g. ispaghula, methylcellulose, sterculia)

Bulk laxatives are those that most closely copy the normal physiological

mechanisms involved in bowel evacuation and are considered

by many to be the laxatives of choice. Such agents are especially useful

where patients cannot or will not increase their intake of dietary fibre.

Bulk laxatives work by swelling in the gut and increasing faecal mass

so that peristalsis is stimulated. The laxative effect can take several

days to develop.

The sodium content of bulk laxatives (as sodium bicarbonate)

should be considered in those requiring a restricted sodium intake.

When recommending the use of a bulk laxative, the pharmacist

should advise that an increase in fluid intake would be necessary. In

the form of granules or powder, the preparation should be mixed with

a full glass of liquid (e.g. fruit juice or water) before taking. Fruit juice

can mask the bland taste of the preparation. Intestinal obstruction

may result from inadequate fluid intake in patients taking bulk laxatives,

particularly those whose gut is not functioning properly as a

result of abuse of stimulant laxatives.

Osmotic laxatives (e.g. lactulose, Epsom salts, Glauber’s salts)

Lactulose works by maintaining the volume of fluid in the bowel. It

may take 1–2 days to work. Lactitol is chemically related to lactulose

and is available as sachets. The contents of the sachet are sprinkled on

food or taken with liquid. One or two glasses of fluid should be taken

with the daily dose. Lactulose and lactitol can cause flatulence,

cramps and abdominal discomfort.

Epsom salts (magnesium sulphate) is a traditional remedy that,

while no longer recommended, is still requested by some older customers.

It acts by drawing water into the gut; the increased pressure

results in increased intestinal motility. A dose usually produces a

bowel movement within a few hours. Repeated use can lead to dehydration.

Glycerin suppositories have both osmotic and irritant effects and

usually act within 1 h. They may cause rectal discomfort. Moistening

the suppository before use will make insertion easier.

Lubricant laxatives (e.g. liquid paraffin)

Liquid paraffin works by coating and softening the faeces; it prevents

further absorption of water in the colon. Long-term use can result in

impaired absorption of fat-soluble vitamins (A, D, E, K). Leakage of

liquid paraffin through the anal sphincter may occur, causing embarrassment

and unpleasantness. If liquid paraffin is inadvertently inhaled

into the lungs, lipid pneumonia can develop. Inhalation couldoccur during vomiting or if acid reflux (regurgitation) is present. The

unpleasant and dangerous effects of liquid paraffin have led to restrictions

in the UK on the pack size that can be sold. Pharmacists have an

important role in discouraging the use of liquid paraffin, which has

little valid therapeutic use.

Constipation in children

Parents sometimes ask for laxatives for their children. Fixed ideas

about regular bowel habits are often responsible for such requests.

Numerous factors can cause constipation in children, including a

change in diet and emotional causes. Simple advice about sufficient

dietary fibre may be all that is needed. If the problem is of recent

origin and there are no significant associated signs, a single glycerin

suppository together with dietary advice may be appropriate. Referral

to the doctor would be best if these measures are unsuccessful.

Constipation in pregnancy

Constipation commonly occurs during pregnancy; hormonal changes

are responsible and it has been estimated that one in three pregnant

women suffers from constipation. Dietary advice concerning the

intake of plenty of high-fibre foods and fluids can help. Oral iron,

often prescribed for pregnant women, may contribute to the problem.

Stimulant laxatives are best avoided during pregnancy; bulkforming

laxatives are preferable, although they may cause some abdominal

discomfort to women when used late in pregnancy (see

‘Women’s Health’).

Constipation in the elderly

Constipation is a common problem in elderly patients for several

reasons. Elderly patients are less likely to be physically active; they

often have poor natural teeth or false teeth and so may avoid highfibre

foods that are more difficult to chew; multidrug regimens are

more likely in elderly patients, who may therefore suffer from druginduced

constipation; fixed ideas about what constitutes a normal

bowel habit are common in older patients. If a bulk laxative is to be

recommended for an elderly patient, it is of great importance that the

pharmacist give advice about maintaining fluid intake to prevent the

possible development of intestinal obstruction.

Laxative abuse

Two groups of patients are likely to abuse laxatives: those with

chronic constipation who get into a vicious circle by using stimulant

laxatives which eventually results in damage to the nerveplexus in the colon; and those who take laxatives in the belief that they

will control weight, e.g. those who are dieting or, more seriously,

women with eating disorders (anorexia nervosa or bulimia), who

take very large quantities of laxatives. The pharmacist is in a position

to monitor purchases of laxative products and counsel patients as

appropriate. Any patient who is ingesting large amounts of laxative

agents should be referred to the doctor.