Antidiarrheal drugs : Flashcards
(27 cards)
Management of diarrhea:
A- Oral rehydration therapy: Consist of sodium chloride 3.5g/L, potassium chloride 1.5g/L, sodium citrate 2.9g/L, anhydrous glucose 20.0 g/L (total osmolarity 245 mOsm/L)
B- Drug therapy of diarrhea: Preferred treatment consists of fluid and electrolyte replacement, nutritional therapy and, if possible elimination of underlying cause of diarrhea.
There are five types of drugs which are used in the treatment of diarrhea ? mention it
1- Antimotility drugs.
2- Anti-secretory drugs. As sulphasalizine, is used for inflammatory bowel disease.
3- Drugs that increase viscosity.
4- Agents that modify fluid and electrolyte transport.
5- Chemotherapeutic agents (specific antimicrobial).
Antimotility drugs
(loperamide, codeine, and diphenoxylate with atropine): MCQ : All activate opiate receptors on the smooth muscle of the bowel to reduce peristalsis and increase segmentation contractions.
At usual doses , they lack analgesic effect.
Diphenoxylate (2.5mg)
atropine (0.025):(t 1/2-3 hr.)
Important feactures for this preparation (usual doses , they lack analgesic effect)
Diphenoxylate 2.5mg
Atropine 0.025mg
(t1/2-3 hr)
Possibly MCQ
1- Is structurally related to pethidine and affects the bowel like codeine.
2- It is absorbed from the intestine, cross the blood brain barrier, and CNS effect appears
3- Diphenoxylate acts both locally and centrally to reduce intestinal motility. (Atropine) has anticholinergic activity. (Mcq)
However, in these preparation, atropine is added in doses below the therapeutic level in an attempt to prevent abuse by deliberate over dosage.
4- The antidiarrheal action starts in 45-60 minutes and last for 3-4 hours. The usual adult dose is 2 tablet to a maximum of four times a day.
Adverse effect of diarrheal treatment :
Anorexia, nausea, vomiting, abdominal discomfort, dizziness, drowsiness, euphoria, lethargy.
Contraindication of antimotility drugs :
1- Jaundice, atropine intolerance, diphenoxylate allergy,
2- A children below 6 years.
3- Patients with sever colitis.
Loperamide: (t1/2 10 hr)
Possibly MCQ
1- It has morphine-like effects.
2- It also has weak anticholinergic effects on the bowel. It does not penetrate the brain wall and, therefore relatively free of central opiate effect.
3- It is indicated in adult for
a)control and symptomatic relief of acute nonspecific diarrhea and of chronic diarrhea associated with inflammatory bowel disease.
b) traveler diarrhea for symptomatic relieve of secretory diarrhea produce by bacteria, virus and parasite.
4- The action starts in 1-2 hours and last for 6-18 hours. Usual adult dose is 4mg followed by 2mg, after each motion, with a maximum of 16mg in 24 hours.
Contraindication of Loperamide
1- Is children under four years.
2- Constipation.
3- Pseudomembranous colitis associated with broad spectrum antibiotics. It can result in paralytic ileus and distension of abdomen.
Adverse effect of Loperamide
Skin rash, intestinal stasis, and gastrointestinal disturbance.
Contraindication of Loperamide
1- Is children under four years.
2- Constipation.
3- Pseudomembranous colitis associated with broad spectrum antibiotics. It can result in paralytic ileus and distension of abdomen.
Drugs that increase viscosity (adsorbents):
1- The bulk-forming agents also called fluid adsorbents, such as ispaghula
methyl cellulose
aluminum hydroxide
are useful for diarrhea in diverticular disease, and for reducing the fluidity of feces in patients with ileiostomy and colostomy.
2- They act in diarrhea by
A)adsorbing intestinal toxins or microorganisms
B)by coating or protecting intestinal mucosa.
3- They are much less effective than antimotility agents and they can interfere with the absorption of other drugs.
4- Fluid adsorbent like kaolin, are used principally in the short term treatment of diarrhea and is usually given in combination with other drug
Chemotherapeutic agents (specific antimicrobial).
Infective diarrhea:
Travelers’ diarrhea:
It is mostly caused by ingestion of contaminated food and water. The best way to reduce the risk is by avoiding raw, unpeeled fruit and vegetables, and unboiled water.
Agents that modify fluid and electrolyte transport:
As bismuth subsalicylate, used for travelers diarrhea, decreases fluid secretion in the bowel. Its action may be due to its salicylate component as well as its coating action.
Chemotherapeutic agents (specific antimicrobial) Treated by:
- Oral rehydrate therapy.
- One of antimotility drugs for 2 -3 days as loperamide or diphenoxylate with atropine may be given…
- If symptomatic give ciprofloxacin 500mg b.d. on the first day may be given. Usually relief is obtained by one or two tablets.
Specific infective diarrhea:
For diarrhea due to specific organisms as amoebae, giardia, salmonella, shigella, specific chemotherapeutic agents are available , Treated by ..
Drug therapy
It depend whether diarrhea is acute or chronic. In former, fluid and electrolyte replacement are of crucial importance.
Fluid therapy:
Fluid therapy may also suffice in mild diarrhea. In moderate to severe non febrile and non bloody diarrhea, antimotility, antisecretory agents may be needed to control diarrhea.
Classification of laxatives:
Though laxatives can classified according to their chemical groups or their mechanism of action
*The most useful classification of alxatives is according to their clinically observed effects:
1-those causing watery evacuation within 1-3 hours (osmotic):
a- Saline and osmotic purgatives, e.g. magnesium citrate, magnesium hydroxide and sodium phosphate.
b- Polyethylene glycol (PEG).
c- Lactulos
Classification of laxatives:
Though laxatives can classified according to their chemical groups or their mechanism of action
*The most useful classification of alxatives is according to their clinically observed effects:
2- those causing soft and semisolid stool within 6-8hours (irritant and stimulant laxatives):
a- Caster oil and diphenylmethane derivatives e.g. phenolphthalein, bisacodyl, and sodium picosulphate.
b- Anthraquinone derivative e.g. senna and cascara.
Classification of laxatives:
Though laxatives can classified according to their chemical groups or their mechanism of action
*The most useful classification of alxatives is according to their clinically observed effects:
3- those causing softening of stool within 1-3 days (bulk, emollient laxative or surfactant):
a- Bulk-forming laxatives e.g. bran, methyl cellulose, psyllium and ispaghula.
b- Faecal softeners or stool softener as docusate sodium, docusate calcium, docusate potassium
Classification of laxatives:
Though laxatives can classified according to their chemical groups or their mechanism of action
*The most useful classification of alxatives is according to their clinically observed effects:
4-5-6
All of classification Can possibly Mcq
4- Lubricant laxatives: e.g. mineral oil and glycerin suppositories.
5- Prokinetic and other agents for constipation as tegaserod and cisapride.
6- Chloride channel activators: e.g. Lubiprostone.
Note:- All of these drugs, except for chloride channel activator, have a risk of dependency for the user.
1- can cause watery evacuation within 1-3 hours (osmotic) : all true except
2- can cause oft and semisolid stool within 6-8hours (irritant and stimulant laxatives): all true except
3- can cause softening of stool within 1-3 days (bulk, emollient laxative or surfactant): all true except
4- Lubricant laxatives:
5- Prokinetic and other agents for constipation
6- Chloride channel activators:
1/
a- Saline and osmotic purgatives
d- Bulk-forming laxative
c- Polyethylene glycol (PEG).
d- Lactulose.
2- can cause oft and semisolid stool within 6-8hours (irritant and stimulant laxatives): all true except
2/
a- Caster oil and diphenylmethane derivatives
b- Anthraquinone derivative
c- Polyethylene glycol (PEG).
d- Lubiprostone.
3/
a- Bulk-forming laxatives
b- Faecal softeners or stool softener
c- Anthraquinone derivative
d- Lactulose.
4/
mineral oil
glycerin suppositories.
5/
tegaserod
cisapride.
6/
Lubiprostone.
Those causing watery evacuation within 1-3 hours (osmotic):-
a- Saline and osmotic laxatives: Osmotic laxative are frequently used to clear the colon for diagnostic procedures or surgery.
b- Polyethylene glycol: Is softened stools, decrease cramping and gas than other laxative and increase number of a bowel movement.
c- Lactulose: It is a semi-synthetic disaccharide which is not absorbed from the intestine. Oral doses are degraded in the colon by colonic bacteria into lactic, formic and acetic acids. This increases osmotic pressure, causing fluid accumulation, colon distension, soft stools and defecation.
Important features of Polyethylene glycol
1- It clears the bowel by induction of diarrhea.
2- It is indicated for bowel cleansing prior colonoscopy or barium enema.
3- It can be used once in patients with chronic constipation and then prevent constipation by other means.
4- The powder is mixed with 3-4 liters of water and 250 ml of this solution is given every 10 minutes.
Contraindication of watery evacuation
Side effect of watery evacuation
In patients with intestinal obstruction and fluid overload states.
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Are mild, consisting of cramps, flatulence, and abdominal discomfort.
Those causing soft and semisolid stool within 6-8hours (irritant and stimulant laxatives):
Mode of action: The agents in this category,
1-stimulate the accumulation of water and electrolytes in gut lumen
2-also enhance motility of colon.
