Antidiarrheal Agents

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Antidiarrheal agents

Definition

Antidiarrheal agents are prescription and non-prescription medicines that are used to treat diarrhea .

Purpose

Some types of cancer may cause diarrhea. In addition, diarrhea is a common side effect of chemotherapy treatments for cancer. This is because anticancer drugs can damage the cells of the intestines. Radiation treatment for cancer directed at the abdominal region also may cause diarrhea. Diarrhea can result in dehydration and the loss of minerals such as potassium. It may prevent the elimination of waste products in the urine, as the body attempts to conserve water.

Description

The common medicines for treating diarrhea that results from cancer and cancer treatments are:

atropine and diphenoxylate
loperamide
octreotide
opium tincture

Atropine and diphenoxylate are prescribed as a combination medicine with the brand names:

Lofene
Logen
Lomocot
Lomotil
Lonox
Vi-Atro

The generic name product also may be available. Atropine and diphenoxylate, antiperistaltic and anti-cholinergic agents, relax muscles and slow down the movements of the gastrointestinal tract. Diphenoxylate is similar to some narcotics and may be habit-forming if taken in dosages higher than prescribed. Since higher doses of atropine have unpleasant effects, it is unlikely that the combination medicine will be taken in high enough doses to cause diphenoxylate-dependence.

Loperamide slows down the movements of the intestines. The common brand names for this medicine are:

Imodium
Kaopectate II
Maalox Anti-Diarrheal
Pepto Diarrhea Control

Octreotide (brand name Sandostatin) is used to treat diarrhea and other symptoms of some types of intestinal cancers. It also is used to treat insulin-producing tumors of the pancreas and diarrhea caused by chemotherapy.

Opium tincture, also known as camphorated opium tincture or laudanum, is a narcotic that is used to treat severe diarrhea.

Except for loperamide liquid or tablets, all of these medicines require a prescription. Dosages vary with the individual.

Recommended dosage

The atropine-diphenoxylate combination is taken by mouth as a solution or a tablet. It may be taken with food to reduce stomach upset. The initial average dosage is 5 mg (2 tsp or two tablets) three to four times daily. Subsequent doses are once daily, as needed.

Loperamide is taken orally, as a liquid, tablet, or capsule. The usual dosage for adults and teenagers is 4 mg (2 capsules or tablets, 4 tsp of liquid) after the first loose bowel movement, followed by 2 mg after each successive loose bowel movement. The maximum dose is 16 mg of the capsules or 8 mg of the tablets or liquid in 24 hours. Loperamide should not be taken for more than two days unless ordered by a physician.

Following therapy with irinotecan (Camptosar), loperamide doses of 2 mg every two hours while awake and 4 mg every four hours at night are utilized at the onset of diarrhea to prevent severe dehydration and possible hospitalization.

Octreotide is packaged as a kit, for injection into a vein. For treating severe diarrhea from intestinal tumors, the average initial dosage of the long-acting form, for adults and teenagers, is 20 mg injected into the gluteal muscle of the buttocks, once every four weeks for two months. The dosage may then be adjusted by the physician. For the short-acting form, the average initial dose is 50 micrograms (mcg) injected under the skin, two to three times per day. The dosage may be gradually increased up to 600 mcg per day for the first two weeks. The average dosage after two weeks is 50-1500 mcg per day. For children, the usual dosage is 1-10 mcg per kg (0.45-4.5 mcg per lb) of body weight per day.

Opium tincture is taken orally, as a liquid. It may be taken with food to prevent stomach upset. The average adult dose is 5-16 drops, measured from the dropper in the bottle, four times per day, until diarrhea is controlled. It may be diluted with water. After several weeks of treatment, it may be necessary to lower the dosage gradually before stopping the medicine, to lessen the risk of side effects from opium withdrawal.

Precautions

Antidiarrheal agents may cause allergic reactions in some individuals. Atropine and diphenoxylate should not be given to children. Loperamide should not be given to children under six. Opium may cause breathing problems in children up to two years of age. Older adults are more sensitive to diphenoxylate and opium than younger individuals and these drugs may cause breathing problems. Diphenoxylate and loperamide may mask the symptoms of dehydration caused by diarrhea in older individuals, so it is very important to drink sufficient fluids.

Atropine and diphenoxylate

Other medical conditions may affect the use of atropine and diphenoxylate:

alcohol or drug abuse may increase the risk of diphenoxylate addiction
colitis (inflammation of the colon) may become more severe
Down syndrome may cause more severe side effects
dysentery may worsen
emphysema, asthma, bronchitis, or other chronic lung diseases increase the risk of breathing problems
enlarged prostate or urinary tract blockage may cause severe problems with urination
gall bladder disease or gallstones may worsen
glaucoma may result in severe eye pain (rare)
heart disease may worsen
hiatal hernia may worsen with atropine (rare)
high blood pressure may increase (rare)
intestinal blockage may worsen
kidney disease may cause atropine to accumulate in the body, resulting in side effects
liver disease may cause central nervous system side effects, including coma
myasthenia gravis may become worse
overactive or underactive thyroid may cause effects on breathing and heart rate
incontinence may worsen

An overdose of atropine and diphenoxylate can lead to unconsciousness and death. Symptoms of overdose include:

severe drowsiness
breathing problems
fast heartbeat
warmth, dryness, and flushing of skin
vision problems
severe dryness of mouth, nose, and throat
nervousness or irritability

Loperamide and octreotide

Other medical conditions may affect the use of loperamide:

colitis (inflammation of the colon) may worsen
dysentery may worsen
liver disease may increase the risk of side effects

Loperamide should not be used in the presence of fever or blood or mucus in stools.

Medical conditions that may affect the use of octreotide include:

diabetes mellitus, since octreotide may affect blood sugar levels
gallbladder disease or gallstones, since octreotide may cause gallstones
severe kidney disease that may cause octreotide to remain in the body longer

Opium tincture

Side effects of opium tincture may be increased or become dangerous when combined with the following medical conditions:

alcohol or drug abuse
colitis (inflammation of the colon)
heart disease
kidney disease
liver disease
underactive thyroid
head injury or brain disease
emphysema, asthma, bronchitis, or other chronic lung disease
problems with urination or enlarged prostate
gallbladder disease or gallstones
seizures

Opium tincture may be habit-forming, causing mental or physical dependence that can lead to side effects of withdrawal when stopping the medicine. The use of opium tincture during pregnancy can cause dependency in the fetus and symptoms of drug withdrawal or breathing problems in the newborn infant.

Symptoms of opium overdose include:

seizures
confusion
severe restlessness or nervousness
severe dizziness
severe drowsiness
slow or irregular breathing
severe weakness
cold, clammy skin
low blood pressure
slow heartbeat
contracted eye pupils

Side effects

Atropine and diphenoxylate

At low doses, taken for short periods of time, side effects of atropine and diphenoxylate are rare. However, serious side effects may include:

bloating
constipation
loss of appetite
stomach pain with nausea and vomiting

Other, less common or rare side effects of atropine and diphenoxylate include:

dizziness
drowsiness
blurred vision
confusion
difficult urination
dry skin or mouth
fever
headache
depression
numbness in hands or feet
skin rash or itching
swelling of gums

Rare side effects that may occur after stopping atropine and diphenoxylate include:

sweating
trembling or chills
muscle cramps
nausea or vomiting
stomach cramps

Loperamide

Side effects are rare with low dosages of loperamide, taken for a short time. However, severe side effects may include:

bloating
constipation
loss of appetite
stomach pain with nausea and vomiting
skin rash
dry mouth
dizziness or drowsiness

Octreotide

More common side effects of octreotide may include:

irregular or slow heartbeat
constipation
diarrhea
flatulence
discomfort at the site of injection

Less common or rare side effects of octreotide may include:

dizziness or light-headedness
fever
flushing or redness of the face
swelling of feet or lower legs
inflammation of the pancreas with stomach pain, nausea, or vomiting
hair loss
seizures
unconsciousness

Symptoms of high blood sugar (hyperglycemia) from octreotide include:

blurred vision
drowsiness and fatigue
dry mouth
flushed, dry skin
fruity breath odor
increased urination
ketones in urine
loss of appetite
increased thirst
nausea or vomiting
stomach ache
rapid, deep breathing

Symptoms of low blood sugar (hypoglycemia) from octreotide include:

anxiety and nervousness
confusion
blurred vision
cold sweats
cool, pale skin
drowsiness, fatigue, weakness
hunger
fast heartbeat
headache
nausea
nightmares and restless sleep
shakiness
slurred speech

Opium tincture

Side effects of opium tincture that are more common with higher dosages may include:

drowsiness
dizziness, light-headedness, faintness
nervousness
weakness or fatigue
painful or strained urination
frequent urination
decreased volume of urine

Lying down and rising slowly from a seated or lying position may help relieve dizziness.

Rare side effects of opium tincture include:

bloating
constipation
loss of appetite
nausea or vomiting
stomach cramps
fast or slow heartbeat
sweating
rash, hives, or itching
redness or flushing of the face
depression
troubled breathing
convulsions (seizures)

The following side effects may occur after stopping treatment with opium tincture:

runny nose or sneezing
body aches
loss of appetite
diarrhea
stomach cramps
nausea or vomiting
fever
sweating
nervousness or irritability
trembling
insomnia
dilated pupils
severe weakness

Interactions

Atropine and diphenoxylate

Other drugs may interact with atropine and diphenoxylate:

Antibiotics (cephalosporins, clindamycin, erythromycins, tetracyclines) can counteract the effects of atropine and diphenoxylate and make the diarrhea worse.
Central nervous system depressants (alcohol, antihistamines, sedatives, pain medicines or narcotics, barbiturates, seizure medicine, muscle relaxants, anesthetics) may increase effects, such as drowsiness, from both the depressant and the antidiarrheal agent.
Monoamine oxidase inhibitors may cause severe side effects if taken within two weeks of diphenoxylate and atropine.
Opioid antagonists (naltrexone) may cause withdrawal from diphenoxylate addiction; naltrexone will counteract the antidiarrheal effects of the medicine.
Other anticholinergics to reduce stomach acid or cramps may increase the effects of atropine.

Loperamide and octreotide

Antibiotics may interact with loperamide and make the diarrhea worse. Narcotic pain medicines in combination with loperamide may cause severe constipation.

Because octreotide may cause high or low blood sugar, it can interact with the following medicines:

antidiabetic medicines, sulfonylurea
diazoxide (Proglycem)
glucagon
insulin
growth hormone

Opium tincture

The following medicines may increase side effects from opium tincture:

anticholinergics for abdominal or stomach cramps
other antidiarrheal medicines
tricyclic antidepressants

Naltrexone (Trexan) makes opium less effective for treating diarrhea. Alcohol, narcotics, and other central nervous system depressants, including antihistamines, sedatives, prescription pain medicines, barbiturates, seizure medicines, muscle relaxants, or anesthetics, may lead to unconsciousness or death in combination with opium tincture.

Margaret Alic, Ph.D.