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only available in the United States.⁵⁶

      Serotonin receptor agonists

      Tegaserod is a selective partial serotonin (5‐HT4) receptor agonist that promotes gut motility and improves constipation symptoms but since 2007 is not recommended in the elderly due to an increase in cardiovascular ischaemic events.⁵⁷ Prucalopride, a 5‐HT4 receptor antagonist, has been shown to treat chronic constipation by increasing colonic motility and transit. Trials have shown prucalopride can improve symptoms in severe chronic constipation over six months of symptoms despite treatment with at least two different classes of laxatives.⁵⁷ Prucalopride was considered safe in the elderly with minimal cardiovascular‐related adverse events, but recent studies found it is associated with cardiac arrhythmias.

      Opioid antagonists

      Opiate pain medications are well known to cause constipation. Chronic opiate use results in constipation in up to 50% of individuals.⁵⁸ Methadone and fentanyl may be less constipating than other morphine derivatives.^59,60 Opiates potently slow gastrointestinal transit and allow enhanced intestinal absorption of fluid. A rational approach involves outlining a strategy to prevent constipation at the initiation of opiate use, although there have been no high‐quality studies to indicate the best strategy. Peripherally acting mu‐opioid receptor antagonists (PAMORAs) reverse opiate‐induced constipation without affecting the analgesic effects or causing withdrawal symptoms (e.g. nalexagol, naldemedine, and methylnaltrexone).^61,62 A systematic review and network meta‐analysis of randomized controlled trials has shown PAMORAs to be superior to placebo in the treatment of opiate‐induced constipation.⁶³ Methylnaltrexone improved stool frequency in opiate‐induced constipation. It is typically reserved for patients with more refractory symptoms as it is administered by injection every other day.⁶⁴ PEG improved stool form in methadone‐induced constipation.⁶⁵ Stimulant laxatives are also commonly used for opiate‐induced constipation.

      Enemas

The use of enemas in the treatment of constipation is typically limited to the acute situation and institutionalized patients to help with rectal evacuation and prevent faecal impaction. There is no medical evidence to support the routine use of phosphate enemas in the treatment of constipation.⁶⁶ The use of phosphate enemas is well described to cause serious hyperphosphatemia, especially in patients with renal insufficiency.⁶⁷ Any enema must be used with caution owing to the risk of colonic perforation.⁶⁸ Soap suds enemas should not be used. Small‐volume tap water enemas may be helpful in emptying the rectum. Larger‐volume tap water enemas may be used on occasion, but even these can result in hyponatraemia.⁶⁹ Although generally considered beneficial, there is currently no trial evidence evaluating the use of arachis oil enemas. Retention enemas containing arachis oil both lubricate and soften impacted faeces and are routinely given at night. The patient’s allergy status must be checked as they contain nut oils.

      Miscellaneous agents

      Probiotics are widely available as a non‐pharmacological treatment option for constipation as components of bio yoghurts and dietary supplements. The faecal flora changes with increasing age, mostly by a fall in the numbers of bifidobacteria.⁷⁰ It remains unclear if this is the cause or the effect of constipation. Large, randomized controlled trials have failed to show a significant benefit from treatment with probiotics.

      Misoprostol, a prostaglandin agonist, stimulates intestinal secretion and intestinal transit. Its use is limited by the common occurrence of side effects, including abdominal pain and cramping.⁷¹ Its use is reserved for patients with refractory constipation.

      Colchicine, well known for causing diarrhoea in the acute treatment of gout, may be used in patients refractory to other medications.⁷² Colchicine frequently causes increased symptoms of abdominal pain, limiting its use.

      Glycerine suppositories have long been used as an over‐the‐counter agent for stimulating bowel movements. The medical literature is lacking in assessments of their effectiveness.

      Neostigmine, an acetylcholinesterase inhibitor, produces prompt colonic decompression. The use of neostigmine is reserved for hospitalized patients with acute colonic pseudo‐obstruction, and benefit has been seen in the treatment of refractory constipation.⁷³

Special categories of constipation

      Medication use is strongly correlated with the development of constipation in older people. Where possible, unnecessary medications should be discontinued and necessary medications switched to a less‐constipating alternative when one is available. For example, verapamil causes more constipation than other calcium channel blockers. Opiate‐induced constipation should be managed as discussed above.

      Randomized controlled trials have established that biofeedback therapy is effective, and it has become the mainstay treatment for dyssynergic defecation. It involves four to six sessions using visual and verbal feedback techniques to improve symptoms of chronic constipation. The goal is to restore a normal pattern of defecation with neuromuscular training. It aims to correct the incoordination of the pelvic floor and anal sphincters to achieve normal and complete evacuation.⁷⁴ Second, it aims to increase rectal sensory perception in those patients who have impaired rectal sensation. The studies concluded that biofeedback therapy is a superior treatment compared to diet, exercise, laxatives, or diazepam for dyssynergic defecation.⁷⁴

      Individuals with dementia frequently develop constipation. Simple first‐line measures include reviewing prescription medications, increasing dietary fibre and fluid intake, and increasing activity levels. Sorbitol and lactulose have been reported to be successful treatments in an observational study, and regular use of an osmotic laxative was recommended to avoid the cost and discomfort of rectal laxatives.⁷⁵ Prevention should be the preferred strategy, as people with dementia may have difficulty recognizing and communicating their symptoms effectively. Highlighting constipation as an important and reversible illness to relatives and carers aims to prevent constipation and hospitalization. Non‐verbal signs that the person may need to defecate include fidgeting, pacing, and pulling at their clothes. Helping the person identify where the toilet is can reduce them resisting their urge to defecate: for example, a clear sign on the bathroom door, an easy access route, and a contrasting toilet seat colour to aid identification. Timed toileting every 2 to 4 hours and 30 minutes after meals can improve continence and prevent constipation.

      People with Parkinson’s disease can have a variety of non‐motor symptoms, including urinary disturbance, sialorrhea, anosmia, and abnormal sweating. Constipation commonly occurs in Parkinson’s disease related to dyssynergic defecation from incoordination of the pelvic floor musculature during defecation and the constipating effect of medication used to treat Parkinson’s disease. It is a key symptom that is an important feature to be elicited as it can lead to abdominal discomfort, nausea, and reduced appetite. Constipation has also been associated with reduced efficacy of medications due to reduced absorption. The treatment is as usual with a high fibre diet, increased fluid intake, and laxatives as required. Psyllium has been used successfully to treat constipation in these patients.⁷⁶ Entacapone inhibits catechol‐O‐methyltransferase, preventing the peripheral breakdown of levodopa and allowing more levodopa to reach the brain. A side effect of entacapone is diarrhoea, so it can be a useful treatment if simple measures are ineffective.

Constipation after an acute stroke is common; the prevalence varies from 30 to 60%. The occurrence of constipation was found to be associated with increased dependency, use of the bedpan for defecation, and high National Institutes of Health Stroke Scale (NIHSS) score. Other possible risk factors included polypharmacy, dehydration, and physical inactivity. Constipation was associated with a poor outcome at 12 weeks.⁷⁷ Chronic functional constipation is common in stroke survivors. Studies have demonstrated that colon transit is significantly reduced, attributed to the dysregulation of the central nervous system. A recent randomized controlled

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