GI - Constipation Flashcards
Symptoms of constipation
Passage of hard, dry stools less frequently than the person’s normal bowel movements (this can range from 2-3 times a day to 1-2 times a week, depending on
the individual’s own routine). This may be associated with symptoms of abdominal discomfort, bloating, and nausea.
Constipation - Cautions and when to refer:
- Continuous use of stimulant laxatives can cause the contents of the gut to be expelled such that no bowel movement occurs for 1-2 days leading to the person wanting to take more laxative. Continuous overuse of stimulant laxatives can result in loss of muscular activity (damage to the nerve plexus) in the bowel wall so that bowel movement is restricted leading to a greater risk of constipation
- Use of laxatives can be abused by people who believe that they help to control weight e.g. by anorexic individuals
- Constipation accompanied by weight and appetite loss (may indicate carcinoma)
- Tarry, red, black or bloody stools also indicate an underlying condition e.g. haemorrhoids, gastric ulcer or gastric carcinoma
- > 40 years old presenting with marked change in bowel habit for first time (may indicate colorectal cancer), then referral is needed.
- Constipation with weight gain, lethargy (anemia?), coarse hair or dry skin (suggests hypothyroidism)
- > 14 days duration with no identifiable cause (Suspect underlying cause that requires fuller investigation by GP)
Certain drugs can cause constipation e.g.
- Opioid analgesics,
- Anticholinergic: Trihexyphenidyl, hyoscine, oxybutynin, procyclidine, tolterodine
- Antidepressant: SSRIs, TCAs, reboxetine, venlafaxine, duloxetine, mirtazapine
- Iron,
- Chlorpheniramine,
- Bendroflumethiazide,
- Propranolol,
- Aluminium/calcium-containing antacids,
- CCB: verapamil, Diltiazem
- Alendronic acid
- Anti-epileptic ( carbamazepine, oxcarbazepine)
- PPI
- NSAIDs: Meloxicam;
- Baclofen (muscle relaxant)
- Lipid lowering agent (Cholestyramine, colestipol, rosuvastatin, atorvastatin (other statins uncommon), gemfibrozil)
- Immunosuppressant (Basiliximab, mycophenolate, tacrolimus)
- α-blocker: Prazosin
- Antipsychotic: Phenothiazines, haloperidol, pimozide and atypical antipsychotics such as amisulpride, aripiprazole, olanzapine, quetiapine, risperidone, zotepine, clozapine
- Beta-blocker: Oxprenolol, bisoprolol, nebivolol;
- CNS stimulant: Atomoxetine
- Cytotoxic: Bortezomib, buserelin, cladribine, docetaxel, doxorubicin, exemestane, gemcitabine, irinotecan,
mitoxantrone, pentostatin, temozolomide, topotecan, vinblastine, vincristine, vindesine, vinorelbine - Dopaminergic: Amantadine, bromocriptine, cabergoline, entacapone, tolcapone, levodopa, pergolide, pramipexole, quinagolide
- Growth hormone antagonist: Pegvisomant
- Smoking cessation: Bupropion
Constipation Treatment:
• First-line:
- Manage any underlying secondary cause (e.g. stop any medication causing constipation if possible).
- Increase fruit and fibre intake (aim to consume approx. 30g daily), keep
adequately hydrated (2L), and perform regular exercise (recommend 30-60 mins of physical activity on five or more days of the week). - Also, advise on useful toileting routines (e.g. don’t “hold in” or rush their time in the loo to ensure complete defecation).
Constipation Treatment:
• Second-line:
- Use of bulk-forming laxatives (e.g. ispaghula husk) if the above doesn’t resolve the problem (not recommended if opioid-induced). These swell up in the gut to increase faecal mass so that peristalsis is stimulated. The laxative effect usually beings within 24 hours but can take 2-3 days to reach full effect.
Constipation Treatment:
• Third-line:
Switch or add an osmotic laxative (e.g. macrogols, lactulose) if the stools are still hard, or it is difficult to defecate. They work by maintaining the volume of fluid in the bowel. It may take up to 2-3 days to work.
- OR add a
stimulant laxative (e.g. senna, bisacodyl, sodium picosulfate, glycerol suppositories) if the stools are soft but it is still difficult to pass. These work by directly stimulating peristalsis through increasing release of water and electrolytes by the intestinal mucosa. This effect can be achieved within 6-12 hours (e.g. overnight) or even quicker if applied as a suppository (within an
hour). Docusate sodium appears to have both stimulant and stool-softening properties.
Side-effects:
• Lactulose
can cause flatulence, cramps and abdominal discomfort in about 20% of patients, particularly at the start of treatment
Side-effects: Bulk laxatives
If bulk laxatives are not taken with sufficient water there is a risk of oesophageal and intestinal obstruction
Commonly used OTC preparations:
Senokot, Dulcolax, Fybogel, Dulcoease, Lactulose, Normacol, Califig etc.
Constipation Counselling points:
- It is important to have a healthy, balanced diet – plenty of whole grains, certain fruits, and vegetables, and to have a gradual increase in dietary fibre (it may take a few
weeks to benefit). Having insufficient amounts of these could also lead to constipation. - Encourage patients to drink plenty of water as it helps to reduce constipation.
- An estimated 1 in 3 pregnant women suffer from constipation. Raised progesterone levels during pregnancy mean that the gut muscles are more relaxed. Oral iron, often prescribed for pregnant women, may also contribute to the problem. Avoid stimulant laxatives during pregnancy, especially in the first trimester.
- Senna is excreted via the kidney and may colour the urine a yellow-brown to red colour.
Causes of constipation
- eating habits
- medication
- unlikely (IBS, pregnancy)
Which laxative should be used in pregnancy for constipation
bulk forming laxative
If medication is required, four classes of OTC laxatives are available:
bulk-forming agents, stimulants, osmotics and stool softeners.
Prolonged use of lactulose
In children this can contribute to the development of dental caries. Patients should be instructed to pay careful attention to dental hygiene
Onset of action laxatives:
Stimulants are the quickest-acting laxative, usually within 6–12 hours. Lactulose and bulk-forming laxatives may take 48–72 hours before an effect is seen. Stool softeners are the slowest in onset, taking up to 3 days or more to work.
Bulk forming:
Ispaghula husk
- > 6 years
- Likely SE: flatulence and abdominal bloating
- All have to be reconstituted with water before taking. The dose for adults and children >12 years old can range from one to six sachets a day, depending on the brand used and the severity of the condition.
- Fybogel is probably the most familiar branded product used OTC in the UK – adults should take one sachet or two level, 5 mL spoonfuls twice a day and for children aged between 6 and 12, 1⁄2 to one 5 mL spoonful twice daily.
Bulk forming: Methylcellulose
- > 12 years
- Likely SE: flatulence and abdominal bloating
-Methylcellulose is only available as Celevac tablets. The adult dose is three to six tablets twice daily, and each dose should be taken with at least 300 mL of liquid.
Bulk forming: Sterculia
- > 6 years
- Likely SE: flatulence and abdominal bloating
- Both products contain 62% sterculia, but Normacol Plus
also contains 8% frangula. The dose for both products is
the same. Adults and children over 12 years of age should take either one or two sachets or heaped 5 mL spoonfuls, once or twice daily after meals. For children aged between 6 and 12, the dose is half that of the adult dose. - The granules should be placed dry on the tongue and swallowed immediately with plenty of water or a cool drink. They can also be sprinkled onto, and taken with, soft food, such as yoghurt.
Stimulant: Senna
- > 6 years
- Likely SE: Abdominal pain
- no drug interactions
- safe in pregnancy and breastfeeding but avoid in pregnancy due to their stimulant effect on uterine contractions
- Senna is available as syrup, tablets or granules. Dosing of proprietary products differs from those recommended in the BNF and BNF-C. Proprietary products tend to have lower dosing schedules than those advocated in the BNF/BNF-C.
These are: adults and children over 12 years of age should take 15 mg each day (two tablets or 10 mL), preferably at bedtime; children over 6 years of age should take half the adult dose (7.5 mg, one tablet or 5 mL).
Stimulant: Glycerol
- Infant upwards
- Likely SE: Abdominal pain
- Glycerol suppositories are normally used when a bowel
movement is needed quickly. The patient should experience a bowel movement in 15 to 30 minutes. Varying sizes are made to accommodate use in different ages. The 1-g suppositories are designed for infants, the 2-g for children and the 4-g for adults.
Stimulant: Sodium picosulfate (dulcolax pico)
- > 10 years
- Likely SE: Abdominal pain
- Adults and children over 10 years of age should take 5 to 10 mg (5–10 mL) at night.
Stimulant: bisacodyl
- > 4 years
- Likely SE: Abdominal pain
- Bisacodyl tablets are enteric coated and therefore patients should be told to avoid taking antacids and milk at the same time because the coating can be broken down, leading to dyspepsia and gastric irritation
- Bisacodyl is available as either tablets or suppositories and can be given to patients over 4 years of age, although OTC products restrict use to those over the age of 10. The dose for children is 5 mg (one paediatric suppository) and for adults and children over 10 years, the dose is 5 to 10 mg (one to two tablets or one Dulcolax 10 mg suppository).
Osmotic: Lactulose
- Infant upwards
- Likely SE: Flatulence,
abdominal pain and colic - They can be taken by all patient groups, have no drug interactions and are safely used in pregnancy and breastfeeding.
- Lactulose is given twice daily for all ages. The dose for
adults is initially 15 mL (adjusted upward depending on
response), for children between 5 and 18 years of age, the dose is 5 to 20 mL, for those between 1 and 5 years of age, the dose is 2.5 to 10 mL and for children under 1 year of age, the dose is 2.5 mL. It has been reported that up to 20% of patients experience troublesome flatulence and cramps, although these often settle after a few days. It may take 48 hours or longer for it to work.
Osmotic: Macrogols (Movicol)
- They can be taken by all patient groups, have no drug interactions and are safely used in pregnancy and breastfeeding.
- Macrogols are available as powders that are reconstituted with water. They are licensed for chronic constipation and should therefore not be routinely recommended by pharmacists because treatment should be only instigated in those presenting with acute constipation.
Osmotic: Magnesium salts
Magnesium, when used as a laxative, is usually given as
magnesium hydroxide. The adult dose ranges between 30 to 45 mL when needed. It is generally not recommended for use in children but is commonly prescribed in the elderly.
Stool softeners: Docusate
- > 6months
- Docusate sodium is a non-ionic surfactant that has stool- softening properties that allows penetration of intestinal fluids into the faecal mass. It also has weak stimulant properties. Docusate is available as either capsules (DulcoEase, Dioctyl) or solution (Docusal).
- It can be given in children aged 6 months and over.
- Children between the age of 6 months and 2 years should take 12.5 mg (5 mL of Docusal paediatric solution) three times a day.
- For children aged between 2 and 12, the dose is 12.5 to 25 mg (5–10 mL) three times a day.
- Adults and children over 12 years old should take up to
500 mg daily in divided doses. In contrast to liquid paraffin, docusate sodium seems to be almost free of any side effects. Docusate sodium can be given to all patient groups.
If the person has opioid-induced constipation:
Do not prescribe bulk-forming laxatives.
- Offer an osmotic laxative and a stimulant laxative (or docusate is an alternative which also has stool-softening properties).
Advise the person to gradually reduce and stop laxatives once
the person is producing soft, formed stool without straining at least three times per week.
- Laxatives should not be stopped suddenly, and weaning off all laxatives may take several months. The rate of laxative dose reduction should be guided by the frequency and consistency of stools.
- Laxative doses should be reduced gradually, for example after 2–4 weeks when regular bowel movements are comfortable, with soft formed stools.
Prucalopride
Consider treatment with prucalopride if at least two laxatives from different classes have been tried at the highest tolerated recommended doses for at least 6 months, and failed to relieve symptoms, where invasive treatment (such as suppositories, enemas, rectal irrigation and/or manual disimpaction) is being considered.
The prokinetic prucalopride (a selective, high-affinity, serotonin [5HT4] receptor agonist) stimulates gastrointestinal motility. Offer a prescription for 4 weeks and if there is no symptom response following this trial, reconsider the benefit of continuing treatment.
- May be considered for people in whom treatment with other laxatives has failed to produce an adequate response. Should only be prescribed by clinicians experienced in treating chronic constipation. Licensed for use in women and men.
Do not prescribe laxatives if there is suspected:
- Intestinal obstruction or perforation.
- Paralytic ileus.
- Colonic atony or faecal impaction (bulk-forming laxatives).
- Crohn’s disease or ulcerative colitis.
- Toxic megacolon.
- Severe dehydration (bisacodyl).
- Galactosaemia (lactulose).
- History of hypersensitivity to peanuts (arachis oil enema).
Prescribe laxatives with caution if there is:
- Fluid and electrolyte disturbance — discontinue treatment if there are symptoms of fluid and electrolyte disturbance.
- A history of prolonged use — due to the risk of electrolyte imbalance, such as hypokalaemia.
- Cardiovascular disease — do not prescribe more than two sachets of full-strength macrogol compound oral powder in any one hour, and advise the person to discontinue if symptoms of fluid and electrolyte disturbance occur.
- Lactose intolerance (lactulose) — may cause diarrhoea.
- Ischaemic heart disease or arrhythmias (prucalopride).
- Movicol is considered high in sodium, this should be taken into account for those people on a low salt diet.
Adverse effects of laxatives are generally mild and infrequent, and include: Bulk-forming laxatives
— flatulence and bloating. Excessive doses or inadequate fluid intake may cause intestinal obstruction.
Adverse effects of laxatives are generally mild and infrequent, and include: Osmotic laxatives
— abdominal pain or cramps, bloating, flatulence, nausea and vomiting; less commonly dehydration, especially if inadequate fluid intake.
Adverse effects of laxatives are generally mild and infrequent, and include: Stimulant laxatives
— abdominal cramps, diarrhoea, nausea and vomiting. Senna may cause yellowish-brown discolouration of the urine.
Adverse effects of laxatives are generally mild and infrequent, and include: Prucalopride
— headache, nausea, diarrhoea, abdominal pain.
Note: excessive doses of laxatives may cause
diarrhoea, which if prolonged, may cause electrolyte disturbances such as hypokalaemia.
