Laxatives: Nursing pharmacology

Laxatives are a group of medications that help the passage of stool and are used to relieve constipation. Now, based on their mechanism of action, laxatives can be broadly divided into four main groups osmotic laxatives, stimulant laxatives, bulk forming agents, and emollients or stool softeners.

Most of these medications are taken orally, but some of them can also be given rectally in the form of enemas or suppositories to cleanse the bowels before procedures like colonoscopies or surgeries.

Starting with osmotic laxatives, these include saline laxatives such as magnesium hydroxide, magnesium citrate, and sodium phosphate salts, and indigestible sugars and alcohols like lactulose and polyethylene glycol.

Both saline laxatives and indigestible sugars and alcohols are not well absorbed or digested, so they draw more water out of the intestinal cells and into the lumen via osmosis.

This increases intestinal motility, called peristalsis, which pushes the stool through the gastrointestinal tract and also helps mix the stool with water.

Moving on to bulk forming agents, these include methyl cellulose, polycarbafyl, and psyllium. Now these medications can't be digested by the enzymes in our gastrointestinal tract, so they remain in the intestinal lumen and end up getting incorporated into the stool.

As a result, bulk forming agents work by drawing in more water, making the stool swell up into a soft, bulky mass which is easier to pass while also stimulating peristalsis.

Next are stimulant laxatives like bisocodil and senna. These medications are also known as irritant laxatives, since they work by irritating the nerve endings in the large intestinal walls.

As a result, these medications stimulate smooth muscle contraction, thereby increasing intestinal peristalsis. Finally, emollient laxatives or stool softeners mainly include docusate and are more effective in preventing rather than treating constipation.

Docusate is a surfactant, which means it has a hydrophilic head that's water soluble and a hydrophobic tail that's water insoluble, so it sticks out into the fat and lipids.

This disrupts the normal surface tension between water and fat, which allows the water to penetrate the stool and make it softer.

OK, now each group of laxatives has its own set of side effects. With osmotic laxatives, the most common ones are diarrhea and fluid loss, which can lead to dehydration and electrolyte disturbances, and severe cases may result in arrhythmias.

In addition, as a boxed warning, clients who use sodium phosphate for colon cleansing before colonoscopy may develop acute phosphate nephropathy.

On the other hand, lactulose may result in cramping, bloating, and flatulence due to the production of methane by the bacteria that feed on the osmotic laxatives.

For bulk forming agents, the main side effects are nausea, vomiting, bloating, flatulence, and diarrhea. Moving on to stimulant laxatives, common side effects include abdominal cramping, nausea, vomiting, diarrhea, and weakness, but also fluid and electrolyte imbalance.

Reddish brown urine may also be observed due to the excretion of senna in the urine. In some cases, senna can also lead to melanosis coli, which is an asymptomatic dark discoloration of the colon wall that is reversible when the medication is stopped.

Finally, stool softeners may result in side effects like nausea, vomiting, abdominal cramping, and diarrhea. In terms of contraindications, laxatives are not recommended for routine use.

In addition, all laxatives should be avoided if intestinal obstruction is suspected, as they could worsen it. As far as specific contraindications go, saline laxatives are contraindicated in clients with renal or hepatic impairment, as well as cardiac conditions.

Clients with diabetes mellitus should also avoid indigestible sugars and alcohols like lactulose, as it may affect their blood glucose levels.

Finally, stimulant laxatives should also be avoided in clients with severe abdominal pain, nausea, or vomiting. All right, if your client is prescribed a laxative, first ask them about the onset and duration of their constipation, the presence of flatus, and any related symptoms like nausea, abdominal pain, or bloating.

Also ask about their normal elimination pattern, including stool frequency, characteristics, and if they ever have to strain when having a bowel movement.

Next, review your client's history for conditions that can contribute to constipation, such as impaired mobility, nutritional deficiencies, and conditions like diabetes or hypothyroidism.

Also review your client's medications, noting any supplements or medications associated with constipation, such as iron or calcium supplements or medications like certain antacids, anti-hypertensives, or antidepressants.

Assess your client's vital signs and perform an abdominal assessment to check for any localized tenderness, distention, or altered bowel sounds.

Also note recent laboratory results, including CBC, comprehensive metabolic panel, or thyroid function tests. Next, explain how the medication works to relieve their constipation and inform them of common side effects they may experience, such as abdominal cramping, bloating, flatulence, and diarrhea.

Teach your client to always swallow the medication whole with at least 8 ounces of fluid, and to increase their daily fluid intake while taking a laxative.

Also stress the importance of contacting their healthcare provider if their constipation is not relieved, if they notice signs or symptoms of dehydration or electrolyte imbalance such as thirst, dark yellow urine, decreased urinary output, muscle cramps.

Or dizziness. Lastly, advise your client to take their medication for the prescribed duration and caution them that prolonged use of laxatives can cause dependence on them, which can make it difficult to have a bowel movement without the aid of a laxative.

Next, discuss lifestyle modifications that can help keep their gastrointestinal tract functioning normally. Remind them about the importance of eating fiber-containing foods, adequate intake of fluids, and regular physical activity.

Lastly, explain how ignoring the urge to defecate can cause their stool to become harder, drier, and more difficult to pass, and even worse, the urge to have a bowel movement could eventually go away if it is routinely ignored.

Now, if your client is prescribed an osmotic laxative like magnesium hydroxide, explain how this type of laxative can cause significant water loss.

So each dose should be followed by 8 ounces of water. Reinforce the need to increase their fluid intake to help prevent dehydration and promote the formation of a softer stool.

When a stimulant laxative like Senna is prescribed, let your client know that the medication can cause their urine to turn reddish brown and reassure them that this will resolve after treatment.

OK, if your client is prescribed a bulk forming laxative like psyllium, explain how this type of laxative acts much like dietary fiber in the body, so it can be taken daily to help prevent constipation without causing dependence.

If they're prescribed the laxative in a powder form, instruct them to mix it with 8 ounces of water or juice and to drink it right after mixing before it has a chance to thicken.

Then instruct them to immediately follow the medication with an additional 8 ounces of water to prevent the fiber from forming a solid mass that could cause an intestinal obstruction.

Lastly, teach your client to separate the bulk forming laxative and any other medications they're prescribed by 1 to 2 hours to ensure all their medications are properly absorbed.

Now your client could be prescribed a stool softener like docusate after a surgical procedure to prevent constipation and straining during a bowel movement.

Explain how the medication helps bring water into the stool to soften it for easier elimination, and that it may take up to 3 days to produce a soft, formed stool.

All right. As a quick recap, laxatives are medications used to treat constipation.

Common side effects include diarrhea, abdominal cramping, flatulence, and bloating. Osmotic laxatives bring water into the intestinal lumen, increase peristalsis, and promote the mixing of the stool with water.

Bulk forming agents draw water into the stool, causing it to swell up into a soft, bulky mass. These fiber laxatives can also be taken daily to help prevent constipation.

Stimulant laxatives increase intestinal peristalsis to promote bowel evacuation. Stool softeners are most effective in preventing constipation by helping water to penetrate the stool, making it softer.

Nursing considerations are focused on teaching clients about self-administration, potential side effects, and lifestyle modifications to promote healthy gastrointestinal function and elimination, as well as evaluating for relief of symptoms and return to a normal elimination pattern.