Antidiarrhoeals

Antidiarrhoeals

Most antidiarrhoeals (like laxatives) tackle the symptom but not the underlying cause which is usually infectious in nature. Therefore antimicrobial therapy is mandatory most of the time. However, there are several types of diarrhoea (secretory diarrhoeas) which have a non-infectious cause and must be treated differently, e.g. diarrhoea due to carcinoid syndrome, drug-related diarrhoea, etc. Table 31.2 lists some common drugs associated with diarrhoea.

Classification

■■ Opiates – diphenoxylate, difenoxin, loperamide

■■ Bismuth subsalicylate

■■ Octreotide.

The opiates and bismuth salts have been discussed in detail elsewhere (consult Index).

Octreotide

Octreotide, the acetate salt of a cyclic octapeptide, is the synthetic analogue of somatostatin, a hormone which inhibits the release of somatotropin (human growth hormone), and insulin secretion. It has to be administered parenterally, and is usually injected subcutaneously. It is used in the treatment of refractory diarrhoea (e.g. AIDS-related diarrhoea), Zollinger-Ellison syndrome, endocrine tumours related to the GI tract (carcinoid, gastrinoma, insulinoma, etc.) and acromegaly. Additional uses include treatment of congenital hyperinsu-linism (nesidioblastosis), chylothorax, prolonged recurrent hypoglycaemia after sulfonylurea overdose, severe rheumatoid arthritis, hepatic hydrothorax, severe pancreatitis, diabetic retinopathy and variceal bleeding.

Adverse effects include anorexia, nausea, GI upset (diar-rhoea/steatorrhoea, constipation, abdominal discomfort, flatulence), cholelithiasis, hypoglycaemia/hyperglycaemia, pancreatitis, hypothyroidism, sinus bradycardia, conduction abnormalities and arrhythmias.

Overdose data is limited; hypoglycaemia, flushing, dizzi-ness and nausea have been reported.

Treatment

·      Monitor blood glucose, CBC, ECG, and liver function in symptomatic patients.

·      Monitor fluid and electrolyte status in patients with signifi-cant nausea and vomiting.

·      Significant toxicity is not anticipated after ingestion because of limited bioavailability. Consider gastric decontamination only after very large ingestions.

·      There is no antidote for octreotide overdose. Overdose treatment is symptomatic and supportive.