Frequent passage of liquid or semisolid stools is called diarrhea. This can be cured by using drugs for Diarrhea.It maybe accompanied by abdominal pain. It can be caused by enteric infection, food toxins, malnutrition, inflammation and drugs like reserpine, synthetic prostaglandins, metoclopramide, domperidon, cholinergic drugs, quinidine and purgatives. Dysentery is characterized by abdominal pain and passage of blood and mucous due to infection or inflammation. For infective diarrhea, specific chemotherapy is required.

Diarrhoea may be non-specific. It may be caused by fear, anxiety or apprehension, indigestion and in people on the move. This type of diarrhea can be treated by nonspecific measures. These measures provide symptomatic relief and do not treat the underlying cause. They reduce the frequency of stools and change the consistency, from liquid to semisolid.

1. Oral rehydration therapy: This therapy is effective in majority of patients with watery diarrhea which lead to symptoms due to loss of fluid and electrolytes. As per WHO/UNICEF recommendations, this therapy consists of:

Rx: Sodium chloride 3.5 gm, Potassium chloride 1.5 gm, Sodium citrate 2.9 gm, Glucose 20 gm and Water ad 1 ltrs.

If oral rehydration therapy is not adequate or the patient is severely dehydrated, administer intravenous fluid and electrolytes.

2. Antimotility agents: These drugs for Diarrhea reduce peristalsis. So they help re absorption of water by delaying intestinal transit time. They also increase tone of the rectal sphincter. Tincture of opium and codeine was used earlier but its use has been discontinued because of tolerance and chances of physical dependence. At present, opioid agonists are used. They act on j.t (mu) and 6 (delta) receptors. By stimulating il-receptors they decrease peristaltic movements while by stimulating 8 receptors they have antisecretory effect. Following drugs for Diarrhea are used.

Diphenoxylate is a congener of pethidine. It acts on opioid mu and 6 receptors. It is combined with atropine (diphenoxylate 1 mg + atropine 0.025 mg) to discourage abuse. This combination (lomotil) is given in doses of 1 tablet every 3—4 hours. It may cause nausea, vomiting, abdominal discomfort, dryness of mouth and drowsiness. Since these symptoms appear in children even at near therapeutic doses, its use has been banned in children below the age of six years. Diphenoxin is an active metabolite of diphenoxylate and is available for treatment of diarrhea through drugs for Diarrhea.

Loperamide is also pethidine congener. It is sparingly absorbed. It also acts through stimulation of mu and 8 receptors. It does not cause physical dependence and respiratory depression in therapeutic doses. However, it may cause nausea, vomiting and abdominal discomfort. Recommended dose is 4—8 mg per day. Antimotility agents are contraindicated in infants and children because of danger of induction of paralytic ileus.

Racecadotril acts by increasing local concentration of enkephalins in intestinal mucosa due to inhibition of enkephalinase enzyme. Then enkephalins stimulate a and 8 opioid receptors to produce antidiorrhoeal effects. It is given in doses of 100— 300 mg three times a day. Important side effects are nausea, constipation and headache. Avoid its use in lactating mothers because it is secreted through breast milk.

3. Adsorbents as drugs for Diarrhea: Kaolin, pectin and chalk are adsorbents. They absorb toxins. They have marginal antidiarrhoeal effect. Hence nowadays they are rarely used. Bismuth subsalicylate is an adsorbent as well as exerts local anti-inflammatory effect due to salicylate. It is recommended for traveler’s diarrhea in doses of 520mg four times a day.

4. Antispasmodic drugs for Diarrhea: Atropine and oxyphenonium (antrenyl): These drugs decrease cramps, abdominal pain and diarrhea associated with spasms of the intestines. They may be used alone or in combination with other antidiarrhoeal and antidysentery drugs. Atropine is used in doses of 0.125 and 0.5mg twice a day while oxyphenonium in doses of 5 mg twice a day. Occasional use is devoid of adverse effects. However, its continuous use or its larger dose may cause dryness of mouth, urinary retention and blurring of vision.

5. Other antidiarrhoeal agents: Clonidine is a2-adrenergic agonist. Its anti-diarrhoeal effect is due to:

• Facilitation of absorption of fluids from gastrointestinal tract

• Inhibition of secretion of fluids

• Increase in intestinal transit time

It is used to treat diabetic diarrhea as well as in diarrhea caused by opiate withdrawal in doses of 0.1 mg twice daily.

Berberin is a quaternary plant alkaloid. Its antidiarrhoeal effect is due to its antimicrobial (E. coli and Vibrio cholera) as well as antisecretory and antimotility activity.

Octreotide is a synthetic octapeptide. It has similar actions as that of somatostatin. It is more potent and has longer half-life (1.5—2 hrs) than somatostatin (3 mm). It reduces gastrointestinal tract motility, intestinal fluid and electrolyte secretion, pancreatic secretion and gallbladder contractions.

It is mainly used to treat diarrhoeas associated with carcinoid tumours and vasoactive intestinal peptide (VIP) secretion tumors as well as to treat acromegaly and to prevent variceal bleeding. It is administered in doses of 100 jig s.c. twice or three times a day. Common side effects are nausea, abdominal discomfort arid pain at site of injection. On long-term therapy gallbladder stone formation and hypothyroidism may occur.

[Source: Principles of Pharmacology for Dental Students]