Laxatives

Laxatives

Drugs that are used to treat constipation.
Constipation
I definition:
A. abnormally infrequent and difficult passage of feces through the lower GI tract
B. A symptom, not a disease
C. Disorder of movement through the colon and/or rectum
D. Can be caused by a variety of disease or drugs
II Causes
A. Adverse drug effects
1. analgesics, anticholinergics, iron supplements, aluminum antacids, calcium antacids, opiates, calcium channel blockers, vinca alkaloids
B. lifestyle
1. poor bowel movement habits: voluntary refusal to defecate
2. diet: poor fluid intake and/or low-residue diets or excessive consumption of dairy products
3. physical inactivity: lack of proper exercise, especially in elderly individuals
4. psychologic: anxiety, stress, hypochondria
C. metabolic and endocrine disorders
1. diabetes mellitus, hypothyroidism, pregnancy, hypercalcemia, hypokalemia
D. neurogenic disorders: autonomic neuropathy, intestinal pseudo-obstruction, multiple sclerosis, spinal cord lesions, Parkinson’s, stroke

Laxatives
I Bulk Forming
A. Mechanism of Action
1. high fiber: safest, can take every day
2. absorbs water to increase bulk
3. distends bowel to initiate reflex bowel activity
B. Side Effects
1. impaction
2. fluid overload
C. Interactions
D. Indications
1. acute and chronic constipation
2. IBS
3. diverticulosis
E. Agents
1. psyllium (Metamucil)
2. polycarbophil
3. methylcellulose (Citrucel)
II Emollient
A. Mechanism of Action
1. stool softeners and lubricants
2. promote more water and fat in the stools
3. lubricate the fecal material and intestinal walls
B. Side Effects
1. skin rashes
2. decreased absorption of vitamins
C. Interactions
D. Indications
1. acute and chronic constipation
2. softening of fecal impacts
3. facilitation of bm’s in anorectal conditions
4. Cardiac pts are on these meds to keep vagal nerve from being stimulated
E. Agents
1. docusate salts (stool softeners) Colace, Surfak
2. mineral oil (lubricants)
III Hyperosmotic
A. Mechanism of Action
1. increase fecal water content
2. result: bowel distention, increased peristalsis, and evacuation
B. Side Effects
1. abdominal bloating
2. rectal irritation
C. Interactions
D. Indications
1. chronic constipation
2. diagnostic and surgical preps
E. Agents
1. polyethylene glycol (goLYTELY) used in bowel preps
2. lactulose (Chronulac)
3. sorbitol
4. glycerin
IV Saline
A. Mechanism of Action
1. similar to hyperosmotic
2. increase osmotic pressure within the intestinal tract causing more water to enter the intestines
3. result: bowel distention, increased peristalsis, and evacuation
B. Side Effects
1. magnesium toxicity (with renal insufficiency) be careful w/kidney disease pts
2. cramping
3. diarrhea
4. increased thirst
C. Interactions
D. Indications
1. constipation (causes a lot of water loss, so not used daily)
2. removal of helminths and parasites
3. diagnostic and surgical bowel prep
E. Agents
1. magnesium sulfate (Epsom salts) bowel preps
2. magnesium phosphate (Fleet Phospho-Soda, Fleet enema) bowel preps
3. magnesium citrate, used for bowel preps
4. magnesium hydroxide (MOM) used for elderly pts
V Stimulant
A. Mechanism of Action
1. increases peristalsis via intestinal nerve stimulation
B. Side Effects
1. addiction can occur
2. nutrient malabsorption
3. skin rashes
4. gastric irritation
5. rectal irritation
C. Interactions
D. Indications
1. acute constipation * only for acute
2. diagnostic and surgical bowel prep
E. Agents
1. castor oil
2. senna
3. anthraquinones
4. cascara
5. bisacodyl
VI Nursing Implications
A. Pts should not take a laxative or cathartic if they are experiencing nausea, vomiting, and/or abdominal pain.
B. long term use of laxatives often results in decreased bowel tone and may lead to dependency
C. All laxative tablets should be swallowed whole, not crushed or chewed, especially if enteric coated
D. All laxatives can cause electrolyte imbalances
E. Bisacodyl and cascara sagrada should be given with water due to interactions with milk, antacids, and H2 blockers. (may open too soon with other liquids)
F. Pts should contact their MD if they experience severe abd pain, muscle weakness, cramps, and/or dizziness, which may indicate possible fluid or electrolyte loss.
G. Monitor for therapeutic effect.