How to deal with constipation - The Pharmaceutical Journal

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How to deal with constipation

Susan Allen outlines the causes of and treatments for constipation and discusses special groups pharmacists should consider

Ascending Sigmoid Sebastian Kaulitzki/Dreamstime.com Identify knowledge gaps
colon colon
1. Which drugs predispose to constipation as a
Rectum side effect?

Figure 1: the colon, the end part of the Panel 1: Medical 2. What affects choice of laxative?
digestive system, is divided into four conditions 3. What advice can be given to parents with
sections: the ascending, transverse, predisposing to
descending and sigmoid colon constipation constipated children?

Constipation is a common complaint, with ■ Coeliac disease Before reading on, think about how this article may
incidence estimated at 12–19 per cent.1 ■ Depression help you to do your job better. The Royal
Constipation means different things to ■ Diabetes mellitus Pharmaceutical Society’s areas of competence for
different populations, individual patients and ■ Gastrointestinal pharmacists are listed in “Plan and record”,
health care professionals, so it can be difficult (available at: www.rpsgb.org/education). This
to define. One broad definition of constipa- obstruction (eg, article relates to “common disease states” (see
tion is the passage of hard stools less fre- gastrointestinal appendix 4 of “Plan and record”).
quently than is normal. Many misconceptions carcinoma, ileus, ovarian
surround bowel habits and what is normal, or uterine tumours) ■ Changes in lifestyle (eg, eating different
leading to misdiagnoses and overuse of laxa- ■ Hypercalcaemia foods or at different times, reduced physi-
tives.“Normal” can be anything from passing ■ Hypokalaemia cal activity)
stools two or three times a day to two or ■ Hypothyroidism
three times a week. It is a change from the ■ Irritable bowel syndrome ■ Suppressing the urge to defecate
norm for the individual that is significant. ■ Multiple sclerosis
■ Parkinson’s disease Constipation is frequently experienced by
Cause ■ Damage to pelvic floor pregnant women and older people (particu-
muscles (eg, post larly those in institutions). Increased incidence
Constipation can be classed as primary (idio- childbirth) in older people is multifactorial and reasons
pathic) or secondary (induced by a specific include side effects of medicines, reduced mo-
condition [see Panel 1] or medicine [see bility, reduced intake of fibre-rich food (eg,
Panel 2, p24]). In most cases there is no due to dental problems) and medical condi-
pathological cause. tions. Constipation is an often overlooked
aspect of patient care in acute settings and can
Many non-medical factors predispose to become a significant problem if it does not
constipation.The most significant are: receive necessary attention.

■ Inadequate fluid intake (the normal stool Symptoms
consists of about 70 per cent water and
dehydration results in a hard stool that can Common symptoms of constipation are diffi-
be difficult to pass; dehydration can be culty passing stools, abdominal discomfort and
exacerbated by drugs, such as diuretics) abdominal distension. If untreated, constipa-
tion can lead to:
■ Inadequate dietary fibre (the average UK
adult consumes 12g fibre daily — far less ■ Faecal impaction (when a large mass of
than the 18g recommended by the faeces cannot be passed) and bowel ob-
Department of Health) struction (with potential to progress to
bowel perforation)
■ Dieting (eg, slimming diets can be low in
fibre) ■ Faecal and urinary incontinence
■ Urinary tract infection
www.pjonline.com ■ Rectal bleeding
■ Anal fissures

7 July 2007 The Pharmaceutical Journal (Vol 279) 23

Panel 2: Drugs that can cause constipation Straining to defecate can cause haemor-
rhoids, fainting and cardiac irregularities. It
■ Antacids containing aluminium or calcium can worsen gastro-oesophageal reflux and
■ Some anticonvulsants (carbamazepine, phenytoin, pregabalin) mobilise a deep vein thrombus.
■ Antidepressants, ie, tricyclics and some monoamine oxidase inhibitors (isocarboxazid
Diagnosis
and phenelzine)
■ Antihistamines (predominantly sedating antihistamines) The key feature in diagnosing constipation is
■ Some antimuscarinic drugs used in parkinsonism (benzatropine, orphenadrine, a change in bowel habit from the norm for
the individual. Constipation can result from
procyclidine, trihexyphenidyl [benzhexol]), urinary incontinence and irritable bowel lodged faeces in any part of the large bowel,
syndrome and diverticular disease but this usually occurs in the sigmoid colon
■ Many antipsychotics or rectum (see Figure 1, p23).
■ Calcium supplements
■ Clonidine For chronic constipation, the Rome II diag-
■ Diuretics nostic criteria for functional gastroduodenal
■ Dopaminergic drugs used in parkinsonism disorders is sometimes used for diagnosis. It
■ 5-Hydroxytryptamine receptor antagonists considers bowel habits over three months and
■ Iron includes such parameters as straining at defeca-
■ Opioid analgesics tion; lumpy, hard stools; sensations of tenesmus
■ Verapamil (a continuous feeling of needing to defecate) or
■ Vinca alkaloids blockage; fewer than three bowel movements
weekly and the use of manual techniques (eg,
Panel 3: Commonly used laxatives digital evacuation) to facilitate defecation.

Class Examples Time to effect Patients describing constipation as a new
Bulking agents symptom unattributable to changes in
Stimulant laxatives Unprocessed bran 2–3 days lifestyle, medication or diet, should be re-
Ispaghula husk 2–3 days ferred.Any of the following symptoms should
Faecal softeners Sterculia 2–3 days also trigger referral:
Osmotic laxatives Methylcellulose 2–3 days
■ Constipation alternating with diarrhoea
Bisacodyl (oral) 10–12h ■ The presence of blood or slime, or both,
Bisacodyl (rectal) 20–60min
Senna 8–12h with or in the stools
Dantron in co-danthramer 6–12h ■ Constipation accompanied by abdominal

capsules (with poloxamer “188”) 6–12h pain or vomiting
Dantron in co-danthrusate caps ■ Unintentional weight loss
10–14h ■ Tenesmus
(with docusate sodium)
Sodium picosulphate 12–72h Chronic constipation has been linked to
15–20min an increased risk of colon and rectal cancer.
Docusate sodium (oral) 15–60min However, a transient period of harder stools
Docusate sodium (rectal) 30min or reduced frequency of defecation is a low
Glycerol (suppository) risk symptom for colorectal cancer.
Arachis oil (enema) Up to 2 days
1–3 days Treatment
Lactulose 3–6h
Macrogols 2–4h In 2005, a quarter of the prescriptions for gas-
Magnesium hydroxide BP 30min trointestinal medicines in England were for
Magnesium sulphate 15min laxatives, costing over £50m. (The Table gives
Phosphate (suppository) 8–12h an idea of the laxatives most commonly pre-
Phosphate (enema) scribed and the relative costs.) However,
Sodium citrate (microenema) many constipation remedies are available over
the counter.The aims of treatment are to:
Table: Number of NHS prescriptions and
associated costs of commonly used ■ Restore normal frequency of defecation
laxatives in England 2005* ■ Achieve regular, comfortable defecation

Laxative Number of Cost using the least number of drugs for the
shortest time
prescriptions ■ Avoid laxative dependence
■ Relieve discomfort2
Lactulose 4,328,300 £13,030200
Senna preparations 3,505,600 £6,002,700 In general, all patients benefit from dietary
Ispaghula husk 2,000,700 £8,123,900 and lifestyle advice. A minimum of 18g and
Macrogol 3350 1,411,000 £12,014,400 up to 30g fibre and 2L of fluid daily is rec-
Co-danthrusate ommended for adults.3 However, it should be
74,500 £915,500 noted that fluid increase is contraindicated in
some people (eg, in heart or renal failure).
*From Prescription Cost Analysis, 2005, The Information Centre Most people see benefits in three to five days,
but it can take a month for a new fibre-rich
24 The Pharmaceutical Journal (Vol 279) 7 July 2007 diet to take full effect. Increased exercise is
beneficial in constipation. Patients should also
be encouraged to respond immediately to any
urge to defecate. Failure to do so can result in

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a build-up of faeces that continue to have Panel 4: Constipation in children Continuing professional development
water absorbed from them, making them
more difficult to pass. Constipation is common in childhood and the diagnostic criteria are different from those
for adults. In an infant or preschool child, constipation can be diagnosed if, for two weeks
Laxatives are used when dietary measures or more, the child has pebble-like hard stools most of the time or firm hard stools fewer
are not feasible, when they have failed or than three times a week. There should be no evidence of structural, endocrine or
while waiting for dietary measures to take metabolic disease. Faecal retention can be diagnosed in a child up to 16 years of age
effect.They are also useful in situations where when, for at least 12 weeks, there has been passage of large volume stools less than
straining to pass stools should be avoided (eg, twice a week and retentive posturing (crossing the legs and squeezing the buttocks) to
angina, haemorrhoids), and in drug-induced avoid defecation.1
constipation.
Many conditions predispose children to constipation, including attention deficit
There are four main groups of laxatives: hyperactivity disorder, autism, coeliac disease, cystic fibrosis, dehydration, metabolic
bulk-forming, stimulant, osmotic and faecal- conditions, spinal cord abnormalities and cerebral palsy. In addition, constipation may
softening. There is limited evidence compar- have a psychological cause. For example, pain precipitated by the passage of an
ing the effectiveness of laxatives, so drug uncomfortable stool can cause the child to resist bowel movements in the future. In a
selection should be based on: child with no underlying medical condition there can be anxieties surrounding potty
training or starting school, causing the child to resist the urge to defecate. Frequently,
■ Patient preference dietary factors are involved.
■ How quickly an effect is needed (see
When constipation starts in infancy, serious underlying disease is unlikely. (This does
Panel 3) not apply to newborn babies, where investigation is needed.) Up to six months of age,
■ Whether the stool is hard or soft babies are recommended to receive only breast or formula milk. Breast-fed infants are
■ Side effects rarely constipated. For bottle-fed babies, checking that formula feeds are made
■ Cost according to directions, and not over concentrated, is useful. After six months, solids are
introduced with gradual inclusion of vegetables, fruits and water. From two to five years
Where constipation is not induced by of age, a child’s diet should move towards that of an adult, and by five years old, it should
necessary drug therapy or chronic illness, include five portions of fruit or vegetables daily (although in smaller portions). For
the laxative should be used for a short time toddlers, advice to increase consumption of water, fresh fruit juice with meals (to avoid
until dietary and lifestyle changes become dental caries), cooked and raw fruit and vegetables, can help constipation. Toddlers
effective. drinking large amounts of cows’ milk may be prone to constipation (or diarrhoea). Milk
can reduce appetite for fibre-rich foods.
Bulk-forming laxatives Bulk-forming
laxatives (ispaghula husk, sterculia and Use of laxatives in children should be discouraged, but after dietary measures, they
methylcellulose, which is also a faecal sof- may be used daily for up to two years, under medical supervision or on the advice of a
tener) add mass to faeces to stimulate peristal- health visitor, to establish soft stools that can be passed without discomfort. Once regular
sis. They are particularly useful if stools are bowel function is restored, laxatives can be gradually withdrawn over several months.
small and hard.They take several days for full There is a suggestion that bulk or osmotic laxatives should be tried first and stimulant
effect so are not suitable for immediate relief laxatives or a combination approach tried if this fails. The stool-softening properties of
but can be used by patients with normal gut docusate sodium may help children with megarectum (where rectal accumulation of bulky
motility and uncomplicated constipation. stools over time causes an enlarged rectum and decreased rectal sensation).
They are also used long-term in patients who
are prone to constipation. Proprietary is- Panel 5: Constipation in pregnancy
paghula or sterculia granules should be mixed
with water and taken immediately, Celevac Constipation affects around 38 per cent of pregnant women, largely due to increased
(methylcellulose) is a tablet formulation. It is progesterone levels reducing intestinal motility and increasing gut transit time.1 Other
important to maintain good fluid intake with factors can include nausea and vomiting in early pregnancy (causing changes to diet and
all bulk-forming laxatives to avoid intestinal dehydration), iron supplements, pressure on the bowel from the growing baby and
obstruction. reduced physical activity. Dietary modifications and exercise may be all that is needed. If
laxatives are necessary, agents that are poorly absorbed from the gastrointestinal tract
Bulk-forming laxatives should not be are preferred (eg, bulk forming, faecal softening and osmotic agents). Senna can be given
taken just before going to bed. They com- if other measures fail, but must be used with caution in the third trimester because it can
monly cause increased flatulence and abdom- induce uterine contractions.
inal bloating in the early stages of treatment,
but these settle with time. avoided because they can cause diarrhoea and
fluid and electrolyte imbalance. Bisacodyl
Stimulant laxatives Stimulant laxatives suppositories can cause local inflammation
increase intestinal motility by direct stimula- and dantron can colour urine red.
tion of colonic nerves; they do not act on the
small intestine (bisacodyl is an exception). Susan Allen, PgD Faecal softeners Docusate sodium has
Members of this group include senna (an (Comm), MRPharmS, is a some stimulant activity but is chiefly a faecal
anthranoid derived from plants), dantron (a freelance pharmaceutical softener, lowering surface tension and allow-
synthetic anthranoid associated with bowel ing water to penetrate hard, dry faeces. It is
and liver tumours in animals and restricted to and copy writer from combined with dantron in co-danthrusate for
use in patients who are terminally ill), opioid-induced constipation in palliative care.
bisacodyl and sodium picosulfate (polyphe- Market Harborough
nolics which are hydrolysed to the same Glycerol suppositories and arachis oil
active metabolite). Senna and bisacodyl are enema can be used rectally to soften impacted
most commonly used short-term for acute faeces. Arachis oil should not be used by peo-
constipation. They should be avoided where ple who are allergic to nuts. Liquid paraffin is
there is obstruction. Taken before going to no longer recommended.
bed, they produce a bowel movement the
following morning. They can cause abdomi- 7 July 2007 The Pharmaceutical Journal (Vol 279) 25
nal cramps and prolonged use should be

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Panel 6: Constipation in cancer ■ Warm the enema to body temperature
(eg, using a jug of warm water)
Reduced volume and frequency of defecation is expected in people who are terminally ill.
Most palliative care patients require a laxative because of medication with opioids, ■ Lubricate the nozzle with lubricating jelly
gastrointestinal obstruction or neurological problems. Additional aggravating factors or white soft paraffin to ease insertion
include hypercalcaemia, treatment with cytotoxics, depression (and associated drug
treatment), reduced mobility, nausea, dehydration and reduced fibre intake. ■ Use a towel to lie on
■ The patient should lie on his or her side,
Tolerance to opioid-induced constipation does not develop, so co-prescribing laxatives
from the outset is encouraged. Some opiates are more constipating than others (eg, with knees drawn up
morphine more so, fentanyl less so).4 Where appropriate, patients should be encouraged to ■ The tube length selected (long or short)
consume fibre-rich foods (eg, fruit juice and stewed fruit) and maintain a good fluid intake.
Laxative treatment usually requires both a stool softener and a stimulant laxative depends on patient (or carer) preference
(commonly co-danthrusate) to maintain normal bowel movements. Osmotic laxatives are for ease of use and does not affect nozzle
often given to those intolerant to stimulant laxatives. positioning in the rectum
■ Holding the enema above the upper hip
For opioid-induced constipation, laxative doses are frequently higher than stated in the can aid administration
BNF. Prokinetic agents, such as metoclopramide, can help with delayed gastric emptying. ■ After administration, sphincter muscles
About a third of patients need rectal measures (eg, enemas, manual evacuation) to should be squeezed for a few minutes to
manage constipation. stop the liquid running out

Osmotic laxatives Osmotic laxatives work Action: practice Herbal laxatives Plant extract laxatives are
within the colonic lumen to retain and draw points either bulk-forming (eg, psyllium, linseed,
water into the intestine by osmosis. Lactulose, fenugreek) or stimulant (eg, senna leaves, cas-
macrogols, magnesium salts, phosphates and Reading is only one way to cara bark, aloe latex, buckthorn, alder buck-
sodium salts fall into this group. undertake CPD and the thorn and rhubarb). Evidence comparing
Society will expect to see herbal agents with conventional laxatives is
Lactulose is a semi-synthetic disaccharide various approaches in a lacking, and the British National Formulary
(galactose and fructose combined). It is not pharmacist’s CPD portfolio. recommends herbal laxatives are avoided
absorbed from the gastrointestinal tract, so it 1. Discuss with your staff because their action is unpredictable. They
can be used by people with diabetes. It takes are, however, sold in some pharmacies and
two to three days to take effect so will not five basic questions to ask may be requested by customers. Cautions for
give immediate relief. Side effects are flatu- a person complaining of use apply as with conventional preparations.
lence and abdominal discomfort. constipation.
2. How would you deal with a Special considerations
Macrogol powders (polymers of ethylene teenager buying laxatives
glycol) have shown some benefits over lactu- frequently? Discuss with a As mentioned, some people (eg, pregnant
lose in small, short-term trials. They can be colleague. women and the terminally ill) are more prone
more effective in increasing stool frequency 3. Read the section on to constipation. In addition, constipation in
and reducing straining over four weeks and laxatives in the BNF for children requires special consideration.These
may be less likely to cause flatulence. Children. Which laxatives groups are discussed in Panels 4, 5 (p25) and
However, macrogol powders may be more can be used in children 6.
likely to produce liquid stools. By nature of under two years old?
their action, osmotic laxatives need to be Laxative misuse and eating disorders
accompanied by good fluid intake. Evaluate Laxatives are listed as potential substances of
misuse in the Royal Pharmaceutical Society’s
Magnesium hydroxide is purgative and For your work to be presented practice guidelines. Misuse can occur in those
can be abused, but occasional use is accept- as CPD, you need to evaluate with eating disorders, such as anorexia, but
able. Magnesium sulphate is sometimes used your reading and any other also in normal or overweight individuals.
when rapid bowel evacuation is needed. activities. Answer the Laxative misuse in the UK has been reported
Again this is not suitable for regular use. following questions: What at 2 per cent in secondary school students and
have you learnt? How has it 13 per cent in college students. Pharmacists
Suppositories and enemas Supposit- added value to your practice? need to be aware and ready to advise those
ories and enemas can be used when oral lax- (Have you applied this buying laxatives repeatedly and excessively,
atives are ineffective or there is impaction low learning or had any and direct customers to support agencies.
down in the gastrointestinal tract. feedback?) What will you do
now and how will this be References
Choice of product depends on the site of achieved?
impaction and the type of stools. Relatively 1. Prodigy guidance on the management of constipation.
soft rectal faeces respond to bisacodyl suppos- Available at: www.cks.library.nhs.uk (Accessed on 25 May
itories provided there are no haemorrhoids 2007).
or anal fissures. Hard rectal stools may be
treated with glycerol suppositories which are 2. The management of constipation. MeReC Bulletin 14(6).
hygroscopic, lubricant, and have some stimu- Available at: www.npc.co.uk (Accessed on 25 May 2007).
lant activity.
3. National Prescribing Centre. Management of constipation.
For more severe impaction a softening Prescribing Nurse Bulletin. Available at:www.npc.co.uk.
enema, such as docusate sodium or arachis (Accessed on 17 May 2007).
oil, can be used overnight followed by a
phosphate enema (osmotic laxative) the fol- 4. Constipation and the use of laxatives: a comparison between
lowing morning. Enemas are not intended transdermal fentanyl and oral morphine Available at:
for regular use, but may need to be repeated http://intl-pmj.sagepub.com (Accessed on 17 May 2007).
several times to clear impacted faeces.
Resources
Basic tips that pharmacists can give for ■ www.dh.gov.uk contains information on constipation and the
enema use include:
risk factors for cancer
26 The Pharmaceutical Journal (Vol 279) 7 July 2007
■ www.eatwell.gov.uk contains information on healthy eating
■ www.radcliffe-oxford.com/books/samplechapter/5111

/01_PCF2-398cb9c0rdz.pdf contains information on
constipation in palliative care

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