Module 6 -- Medications to Treat Gastrointestinal problems in Pediatric Patients
   Click for help with this module.

Reading Assignment

Content:



2

Drugs that alter GI Motility

Drugs that alter GI motility are used in:

  • Diseases that affect smooth muscle
  • Diseases that affect absorption or secretion or motility
  • Disease that alter sensitivity of the gut wall

Categories
– Speeder uppers of transit time
– Slower downers of transit time
– Antispasmotics (we won’t discuss in this unit)

Speeder uppers

Prokinetic agents like metoclopramide (Reglan) are also used for GERD as well as nausea and vomiting related to chemotherapy or anesthesia

They increase motility by acting on smooth muscle innervation and increasing sensitivity to acetylcholine, they also antagonize dopamine receptors and therefore may improve nausea.

Side effects
Are related to dopamine (prolactin inhibiting hormone) antagonism (galactorrhea, mastalgia, dyskinesias). They may also interfere with absorption of other drugs because of increased transit time and decreased time for absorption

Other tidbits:

Erythromycin is closely related to motilin and binds to motilin receptor sites in GI smooth muscle so can be used as a prokinetic drug but poorly tolerated

Cisapride (Propulsid) was taken off the market in 2000 for interaction with other drugs in P450 enzyme system leading to arrhythmias

Laxatives and Stool Softeners

Before you guys started graduate school, I know you thought that constipation was really a problem of the elderly. Now you know different and definitely need to know about laxatives and stool softeners. Laxatives are the overall category for medications that increase evacuation of the bowel. Some medications work more on increasing intestinal propulsion and others more on changing the consistency of the stool by increasing fluid in the colon.

Medications Indicated for clean out or disimpaction (every parent’s favorite job!)

Enemas

Example: Hypertonic phosphate enemas (Fleets)

They work by drawing water into the colon to soften stool and increase motility.

Bulk (Fiber) Agents
Example: Psyllium (Metamucil)
Bulk agents are not absorbed from the GI tract but soften fecal mass and increases bulk which stretches intestines and increases peristalsis.

WARNING: Requires adequate fluid intake

Side effects: bloating, gas, abdominal pain

Emollient Agents

Example: Ducosate Sodium (Colace)

Emollients increase absorption of water into colon, and the water mixes with stool.

Example: Mineral Oil, which is not absorbed in the GI tract but mixes with feces and lubricates it.

Side effects
– Possible impairment of absorption of fat-soluble vitamins over time
– May need to add vitamin supplement if > 1 month therapy required
– Cramping, nausea & vomiting

Stimulants

Stimulants are Diphenylmethane derivatives.

Example: Dulcolax (Bisacodyl)
It works by stimulating the enteric NS and increasing Cl- ion secretion (making the EqM potential more positive) therefore increases smooth muscle contraction and peristalsis.

Available as suppositories or tablets

Side effects
• F/E imbalance (loss of Cl-, cramping, nausea, vomiting)

WARNING: High abuse potential

Other Stimulants
• Anthraquinone derivatives (Senna)
• Castor oil

Try to use stimulant medications only for clean-out, NOT for maintenance therapy for constipation

Saline preparations

Example: Magnesium hydroxide (MOM)
It osmotically draws fluid into the intestine and stimulates cholecystokinin release which stimulates peristalsis

Side effects
• F/E imbalance
• Dizziness
• Nausea and vomiting
• Neuromuscular s/e from magnesium

• Other: sodium phosphate (fleet’s oral prep)

Hyperosmolar preparations

Example: Lactulose (fructose and galactose)
These cause osmotic water retention in intestines

Side effects
• GI related
• Hypernatremia and lactic acidosis in high doses

Other examples are Sorbitol

And don’t forget the ever-popular Glycerin suppositories!

Non-Hyperosmolar preparation
Best (as in miracle) drug for constipation

Polyethylene Glycol (Miralax)

If you look at the package insert you will find that Miralax is not FDA approved for children, but it is given with great anecdotal support by leading gastroenterologists everywhere, including at UNC at Chapel Hill.

It comes as a powder that dissolves in liquid with NO taste or consistency change to the liquid. This increases compliance tremendously. Try it, you’ll like it! It is given once or twice daily depending on the need. Stool softners for constipation and often work best if given for at least 3-6 months, often much longer.

Side effects, of course, are GI related.
Gas
Cramping
Bloating
Diarrhea

Slower Downers

Anti-diarrheal Drugs

In general, anti-diarrheal drugs should be avoided. Most causes of diarrhea are viral in children in developed countries and the best therapy is to keep the child hydrated and well nourished until the illness has passed. In fact, studies have demonstrated that symptoms will persist longer if anti-diarrheal drugs are used.

However, there are a few circumstances where you might safely prescribe or recommend these drugs. True concern for dehydration might be an indication to temporarily decrease diarrhea water loss. Kids with significant life events like SATs or possibly another competition that cannot be postponed or avoided (not necessarily talking about sports here, but possibly, etc.)

Opioids

Example: Imodium (loperamide)

It is approved for ages 2 and up and works to decrease propulsion by acting on GI smooth muscle (anticholinergic effects). It may be habit forming and not because of it’s anti-diarrheal effects!

Side effects:

Most serious is paralytic ileus

Drug interactions:
Do not use with MAOIs because can lead to hypertensive crisis.

Adsorbents (anti-secretory drugs)

In general are safer than Opioid preparations.

Examples:

Attapulgite (Kaopectate)

Approved for ages 3 and up and works by increasing adsorption of fluids from the GI tract.

Bismuth subsalicylate (Pepto-Bismol)

It works the same as above and has an antimicrobial action (sometimes used for PUD as well).

Contraindications:

Allergy to salicylates.

Since is does contain a salicylate (like Aspirin) it is contraindicated in influenza and chicken pox because of the risk of Reye’s syndrome.

Anti-emetic Drugs

Like anti-diarrheal drugs, anti-emetic drugs are not commonly prescribed in pediatrics. It is very important to remember that if you need to treat vomiting you should first assess for:
1) Suspected etiology (treat that if can)
2) If severe, treat for fluid and electrolyte issues (see module 6b)
3) If still unmanageable add drug therapy (see below)

Anti-emetic Drugs Used in Children

The reason you are considering using an anti-emetic is because a child cannot keep any fluids down, so it makes sense that these 3 products come as rectal suppositories. There is nothing better than a rectal medication when a child is vomiting. Trust me!

Examples:

Prochlorperazine (Compazine)
It works by selectively antagonizing D2 (dopamine) receptors in the CNS. This medication is also very sedating and can cause respiratory depression when used in conjunction with other medications that cause sedation or in overdose.

Promethazine (Phenergan)
It is a non-selective antihistamine, antagonizing central and peripheral H1 receptors. It is only approved for children 2 and older. Side effects with this medicine are the same as any anti-histamine but with more central effects causing more sedation.

Trimethobezamide (Tigan)
Tigan has an unknown mechanism of action but it is probably a dopamine receptor antagonist. This is probably the first choice and has the least possibility of drug interaction and adverse effects.

Back to top NEXT >>