Hyperosmotic Laxatives: Caution For Specific Patient Groups

Hyperosmotic laxatives are used to treat constipation and empty the bowels before medical procedures. However, they are not suitable for everyone. Patients taking opioid medications for pain should be cautioned against taking hyperosmotic laxatives as they can cause increased central nervous system depression when combined with opioids. Additionally, hyperosmotic laxatives are not recommended for long-term use as they can lead to serious bowel motility dysfunction, including intestinal paralysis, cathartic colon, and irritable bowel syndrome.

Patients taking opioid medications for pain

Opioids are a type of prescription pain medication that blocks pain signals by attaching to receptors throughout the nervous system, including the gut. When opioids attach to receptors in the gut, it lengthens the time it takes for stool to pass through the gastrointestinal system, leading to constipation. Constipation is defined as having fewer than three bowel movements a week.

Opioid-induced constipation (OIC) affects between 40 and 60% of patients without cancer who are taking opioids. It is important to note that OIC may present immediately when a patient starts taking opioids, or it may develop gradually during opioid therapy. In addition to constipation, patients may experience other gastrointestinal side effects such as nausea, vomiting, bloating, abdominal pain, and straining.

To prevent OIC, it is recommended to start laxatives at the same time as opioid therapy. However, bulk-forming laxatives should be avoided as they can increase the risk of bowel obstruction. Instead, stimulant laxatives (e.g. biscacodyl, senna-sennosides), osmotic laxatives (e.g. oral magnesium hydroxide, polyethylene glycol), and mineral oil laxatives can be used.

If OIC has already developed, treatment options include pharmacological and non-pharmacological therapies. Stimulant laxatives, osmotic laxatives, and mineral oil laxatives can be used to treat OIC. Additionally, increasing dietary fiber, fluid intake, and physical exercise can help prevent and treat OIC.

It is important for healthcare providers to educate patients about the risk of constipation when prescribing opioids. Patients should be encouraged to eat a high-fiber diet, drink ample water, and exercise regularly to promote bowel motility. An interprofessional approach involving clinicians, nurses, pharmacists, and gastroenterologists can help improve patient outcomes and reduce the occurrence of adverse drug reactions.

Pregnant or breastfeeding women

Pregnant women should be cautious about taking hyperosmotic laxatives. Constipation is a common issue during pregnancy, and while natural remedies such as increasing fibre and fluid intake or exercising are recommended as the first line of treatment, they may not always be effective. In such cases, mild laxatives like Milk of Magnesia, bulk-forming agents, or stool softeners may be considered safe during pregnancy. However, it is always advisable to consult a doctor before taking any medication, especially during pregnancy.

If natural remedies and mild laxatives are ineffective, stronger hyperosmotic laxatives may be considered, but they should be used with caution and only under medical supervision. Hyperosmotic laxatives like glycerin, sorbitol, and polyethylene glycol (PEG) can be used for occasional constipation relief. They work by pulling water into the intestines, softening the stool, and stimulating evacuation. However, it is important to note that rectal suppositories or enemas should be avoided if oral laxatives are effective.

While the use of hyperosmotic laxatives during pregnancy has not been extensively studied, they are generally not expected to increase the risk of birth defects when used in recommended doses. Additionally, since they are not well absorbed by the intestine, exposure to the developing fetus is expected to be minimal. Nevertheless, it is always advisable to consult a healthcare provider before taking any medication during pregnancy.

For breastfeeding women, the considerations are slightly different. Most laxatives can be used while breastfeeding as they are either not absorbed or only minimally absorbed from the gastrointestinal tract, resulting in low or negligible levels in breast milk. However, it is still important to consult a healthcare provider for specific recommendations and to perform an individual risk assessment. Prucalopride, a selective serotonin 5HT4-receptor agonist used for chronic constipation, should be used with caution during breastfeeding as it is excreted into breast milk in small amounts.

Lactulose, Macrogol 3350, sodium citrate enemas, bisacodyl, docusate, glycerol suppositories, and standardised senna preparations can generally be used during breastfeeding. While there is limited evidence for the use of these laxatives during breastfeeding, their low oral bioavailability or negligible rectal bioavailability means that passage into breast milk is unlikely, and infant side effects are not expected. However, as a precaution, it is recommended to monitor infants for potential issues such as diarrhoea, vomiting, or irritability.

Patients with diabetes or heart disease

The first step in managing constipation is to make food and dietary changes alongside increasing exercise and making lifestyle changes. If patients are resistant to these changes, laxatives should be the next step in treatment. Treatment should begin with bulking agents such as psyllium, bran or methylcellulose, followed by osmotic laxatives if the response is poor. Osmotic laxatives such as lactulose, polyethylene glycol and lactitol are the most frequently prescribed osmotic agents.

It is important to note that the long-term use of laxatives has been associated with laxative dependence, chronic constipation, and loss of normal bowel function. Chronic use or overdose of laxatives may produce persistent diarrhea, hypokalemia, loss of essential nutritional factors, and dehydration.

In addition, there is a link between constipation and cardiovascular disease, particularly with respect to the progression of atherosclerosis. A study found that the use of laxatives was associated with higher risks of mortality from coronary heart disease and ischemic stroke in men and women, as well as from total stroke in women only.

Therefore, patients with diabetes or heart disease should be cautious when taking hyperosmotic laxatives and should only do so under the supervision of a medical professional.

Patients with renal or liver insufficiency

The American Society of Colon and Rectal Surgeons (ASCRS), the American Society for Gastrointestinal Endoscopy (ASGE), and the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) recommend the use of PEG 3350 electrolyte solutions in patients with renal or liver insufficiency. However, it is important to note that these solutions should be used with caution in patients with renal disease and only under the supervision of a clinician.

When administered rectally, glycerin and sorbitol—both hyperosmotic laxatives—exert a hygroscopic and/or local irritant action, drawing water from the tissues into the feces and stimulating evacuation. PEG 3350 electrolyte solutions, on the other hand, are non-absorbable and pass through the bowel without net absorption or secretion, avoiding substantial fluid and electrolyte shifts.

It is important for patients with renal or liver insufficiency to follow the instructions provided by the manufacturer for the proper methods of reconstitution and administration of the laxatives. They should also be aware of potential side effects, such as malaise, nausea, abdominal distention, and vomiting.

In summary, while hyperosmotic laxatives can be beneficial for patients with renal or liver insufficiency, it is important to use them with caution and under medical supervision. Patients should also be aware of potential side effects and follow the instructions provided by the manufacturer.

Patients with electrolyte or fluid imbalances

The American Society of Colon and Rectal Surgeons (ASCRS), the American Society for Gastrointestinal Endoscopy (ASGE), and the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) recommend the use of PEG 3350 electrolyte solutions for patients with electrolyte or fluid imbalances. These solutions are particularly suitable for individuals with conditions such as renal or liver insufficiency, congestive heart failure (CHF), liver failure, or advanced liver disease with ascites. The PEG 3350 electrolyte solutions are preferred in these cases as they help maintain fluid and electrolyte balance while providing the desired laxative effect.

It is important for patients with electrolyte or fluid imbalances to be cautious and consult their healthcare providers before taking hyperosmotic laxatives. Adjustments to the dosage or alternative treatment options may be necessary to ensure the safe and effective management of constipation in these patients.

Additionally, it is worth noting that hyperosmotic laxatives are generally not recommended for long-term use. The long-term use of laxatives has been associated with adverse effects, including laxative dependence, chronic constipation, and the loss of normal bowel function. Therefore, it is crucial to use these medications with caution and under the supervision of a healthcare professional.

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