LAXATIVES/PURGATIVES/CATHARTICS Flashcards
What about laxatives?
=Laxatives promote evacuation of the intestine. Used to treat constipation.
=They include, cathartics, or purgatives, which
promote rapid evacuation of the intestine and
alteration of stool consistency.
Laxatives can be subdivided into seven categories
according to their action, list the categories
*Bulk-forming laxatives
*Stool softeners
*Emollients
*Saline laxatives
*Stimulant laxatives
*Osmotic laxatives
*chloride channel activator
General info about laxative use
=Many OTC laxatives are overused by a large portion of the population.
=Prevention and relief of constipation is better achieved through natural methods (e.g., high-fiber diet, adequate fluid intake, good bowel habits, and exercise).
=Normal frequency of bowel movements varies from daily to several times weekly.
**When constipation occurs, the cause should be identified before laxatives are used.
I. Bulk-Forming laxatives MoA and Pharmacology
*Not absorbed from the GI tract.
* known as fiber supplements. They soften stool by absorbing water and increase fecal mass.
* Colon distention induces peristalsis, to facilitate defecation.
*The formulation is dissolved in water or juice,
immediately followed with another glass of fluid.
* Administered one to three times per day.
Laxative effect within 12–72 h.
Examples of bulk-forming laxatives
=psyllium
=cellulose derivatives
=polycarbophil
=bran.
Bulk-forming laxatives indications
- Older adults
- Laxative-dependent patients
- Simple constipation unrelieved by natural methods.
- Maintaining regularity for patients with diverticulosis and in increasing the bulk of stools in patients with chronic watery diarrhea.
Precautions or contraindications of bulk-forming laxatives
Patients with acute abdominal pain, partial
bowel obstruction, dysphagia (difficulty in swallowing), or esophageal
obstruction.
II. Stool softeners
=Increase the penetration of water and lipids into compacted fecal material.
=Stool softeners are surface-acting agents that moisten stool through a detergent action and are administered orally.
=Dosage required to soften stools varies widely depending on the condition and patient response.
*The onset of action:12–72 h.
Side effects are rare, with occasional mild, transitory GI cramping or rash.
Examples of Stool Softeners
docusate and glycerin
Indications for Stool softeners
Pregnant, nursing women and children with hard, dry stools.
Precautions or contraindications for Stool softeners
=Acute abdominal pain or prolonged use (more than one week) without medical supervision.
=Avoid stool softeners that also contain stimulant laxatives.
III. Emollients
=Emollients promote stool movement through the intestines by softening and coating the stool.
=Mineral oil may be administered orally and is usually effective in 6–8 h.
=Mineral oil is sometimes administered rectally as an oil-retention enema (60–120 mL).
Side Effects of Emollients
*Seepage of oil from rectum, causing anal irritation
*Malabsorption of vitamins A, D, E, and K only with prolonged oral use
Precautions or contraindications of Emollients
Children under 5-years, Bedridden, debilitated, or geriatric patients, Patients with dysphagia, gastric retention, or hiatal hernia, Pregnancy, Prolonged use, Concomitant use of stool softeners.
IV. Saline laxatives
=Saline laxatives Include: milk of magnesia (MOM) or citrate of magnesia
=They promote secretion of water into the intestinal lumen
=They should be taken infrequently in single doses.
*The onset of action is 0.5–3 h
Side effects of Saline Laxatives
=Side effects are more common when used for prolonged periods or in overdoses.
*Electrolyte imbalance, weakness, sedation, and confusion, Edema, Cardiac, renal, and hepatic complications.
Precautions or contraindications of Saline laxative use
=Long-term use, Heart failure or other cardiac disease, Edema, cirrhosis, or renal disorders, concomitant diuretics, acute abdominal pain,
Colostomy
V. Stimulant laxatives
They are cathartic in action, producing strong peristaltic activity, and alter intestinal secretions
in several ways.
Stimulant laxatives are habit forming; long-term use may result in laxative dependence and the
loss of normal bowel function.
All stimulant laxatives produce some degree of abdominal discomfort.
Sometimes a combination of oral preparations, suppositories, and/or enemas may be ordered
for these purposes.
The onset of action is 0.25–8 h, depending on the preparation.
Stimulant laxatives indications
=Their use should be confined to conditions in which rapid, thorough emptying of the bowel is
required :
*before surgical, proctoscopic, sigmoidoscopic, or radiological examinations, or for emptying the bowel of barium following GI X-rays) or for patients on opioid therapy.
= Sometimes a combination of oral preparations, suppositories, and/or enemas may be ordered
for these purposes.
Stimulant laxatives examples
Senna, castor oil, and Bisacodyl.
Side Effects of Stimulant laxatives
Common with prolonged us:
* Abdominal cramps, discomfort and nausea.
* Rectal and/or colonic irritation with suppositories
* Loss of normal bowel function with prolonged use
* Electrolyte disturbances and dehydration with prolonged use
* Discoloration of urine with Senna
Precautions or contraindications of Stimulant laxatives
=Acute abdominal pain or abdominal cramping—
danger of ruptured appendix, Ulcerative colitis.
=Children, pregnant and lactating women.
VI. Osmotic laxatives
=They exert an action that draws water from the tissues into the feces and reflexively stimulates evacuation.
=Lactulose response may take 24–48 h.
=Side effects include nausea, vomiting, flatulence, andabdominal cramps.
=Osmotic laxatives are also used to treat encephalopathy in hepatic failure precipitated by GI bleeding and other conditions.
Examples of Osmotic laxatives
Lactulose, polyethylene glycol (PEG), and
sorbitol.
